Document Number: MC33978
Rev. 8.0, 7/2018
NXP Semiconductors
Technical Data
© NXP B.V. 2018.
22 channel multiple switch detection
interface with programmable wetting
current
The 33978 is designed to detect the closing and opening of up to 22 switch
contacts. The switch status, either open or closed, is transferred to the
microprocessor unit (MCU) through a serial peripheral interface (SPI). This
SMARTMOS device also features a 24-to-1 analog multiplexer for reading the
input channels as analog inputs. The analog selected input signal is buffered and
provided on the AMUX output pin for the MCU to read.
Independent programmable wetting currents are available as needed for the
application. A battery and temperature monitor are included in the IC and
available via the AMUX pin.
The 33978 device has two modes of operation, Normal and Low-power mode
(LPM). Normal mode allows programming of the device and supplies switch
contacts with pull-up or pull-down current as it monitors the change of state on
the switches. The LPM provides low quiescent current, which makes the 33978
ideal for automotive and industrial products requiring low sleep-state currents.
Features
• Fully functional operation 4.5 V ≤ VBATP ≤ 36 V
• Full parametric operation 6.0 V ≤ VBATP ≤ 28 V
• Operating switch input voltage range from -1.0 V to 36 V
• Eight programmable inputs (switches to battery or ground)
• 14 switch-to-ground inputs
• Selectable wetting current (2, 6, 8, 10, 12, 14, 16, or 20 mA)
• Interfaces directly to an MCU using 3.3 V / 5.0 V SPI protocol
• Selectable wake-up on change of state
• Typical standby current IBATP = 30 μA and IDDQ = 10 μA
• Active interrupt (INT_B) on change-of-switch state
• Integrated battery and temperature sensing
Figure 1. 33978 simplified application diagram
Notes
1. The IC is functional from 4.5 V < VBATP < 6.0 V, but with degraded parametric values. The parameters may not meet the minimum and maximum
specifications when VBATP drops below 6.0 V.
MULTIPLE SWITCH DETECTION INTERFACE
33978
34978
Applications
• Automotive
• Heating ventilation and air conditioning (HVAC)
• Lighting
• Central gateway/in-vehicle networking
• Gasoline engine management
• Industrial
• Programmable logic control (PLC)
• Process control, temperature control
• Input-output control (I/O Control)
• Single board computer
• Ethernet switch
EK SUFFIX (PB-FREE)
98ASA10556D
32-PIN SOICW-EP
ES SUFFIX (PB-FREE)
98ASA00656D
32-PIN QFN (WF-TYPE)
SP0
SG12
SG13
SG0
SP7
SP1
Battery
VBATP
VDDQ
MISO
MOSI
SCLK
AMUX
EP
GND
WAKE_B
Battery
Power
Supply
Power
Supply
VDDQ
MCU
MISO
MOSI
SCLK
AN0
INT_B
CS_B CSB
INTB
SG1
33978
NXP Semiconductors 2
33978
Table of Contents
1 Orderable parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Internal block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Pin connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2 Pin definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 General product characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2 Thermal characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3 Operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.2 Functional block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6 General IC functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.1 Battery voltage ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.2 Power sequencing conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7 Functional block description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.1 State diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.2 Low-power mode operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.3 Input functional block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.4 Oscillator and timer control functional block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.5 Temperature monitor and control functional block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.6 WAKE_B control functional block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.7 INT_B functional block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.8 AMUX functional block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.9 Serial peripheral interface (SPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
7.10 SPI control register definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
8 Typical applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.1 Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.2 Bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.3 Abnormal operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
9 Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
9.1 Package mechanical dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
10 Reference section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
11 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
3NXP Semiconductors
33978
1 Orderable parts
This section describes the part numbers available to be purchased along with their differences.
Table 1. Orderable part variations
Part number Temperature (TA)Package Notes
MC33978EK
-40 °C to 125 °C
SOICW-EP 32 pins
(2), (3)
MC33978AEK
(2)
MC33978AES QFN (WF-TYPE) 32 pins
MC34978EK
-40 °C to 105 °C
SOICW-EP 32 pins
(2), (3)
MC34978AEK
(2)
MC34978AES QFN (WF-TYPE) 32 pins
Notes
2. To order parts in tape and reel, add the R2 suffix to the part number.
3. Refer to errata MC33978ER ER01 for details on current conditions present on the MC33978EK and MC34978EK devices only.
NXP Semiconductors 4
33978
2 Internal block diagram
Figure 2. 33978 internal block diagram
Wetting (2.0 mA to 20 mA)
Sustain (2.0 mA)
Low Power Mode (1.0 mA)
VBATP
To SPI
SG0
VBATP
4.0 V
reference
To SPI
SP0-7
Internal 2.5 V
VBATP
+
-
VDDQ
Inputs
SG0
SG2
SG1
SG13
SP7
SP0
SP1
AMUX
VBATP
VDDQ
GND
SCLK
MOSI
MISO
CS_B
WAKE_B
INT_B
Oscillator
and
Clock control
VBATP, VDDQ
Internal 2.5 V/5.0 V
Power On Reset
Bandgap reference
Sleep Power
Temperature
Monitor and
Control
SPI Interface and
Control
Internal 2.5 V
Internal 2.5 V
Internal 2.5 V
VDDQ
Mux control
24
Interrupt
control
VDDQ
125 kΩ
WAKE_B control
VDDQ
125 kΩ
Internal 2.5 V
VBATP
EP
Internal 2.5 V
4.0 V
reference
VBATP
To SPI
SGx
4.0 V
reference
VBATP
To SPI
SG5
4.0 V
reference
SG5
1/6 Ratio
VDDQ
125 kΩ
Wetting (2.0 mA to 20 mA)
Sustain (2.0 mA)
Low Power Mode (1.0 mA)
Wetting (2.0 mA to 20 mA)
Sustain (2.0 mA)
Low Power Mode (1.0 mA)
Wetting (2.0 mA to 20 mA)
Sustain (2.0 mA)
Low Power Mode (1.0 mA)
Wetting (2.0 mA to 20 mA)
Sustain (2.0 mA)
Low Power Mode (2.0 mA)
5NXP Semiconductors
33978
3 Pin connections
3.1 Pinout
Figure 3. 33978 SOICW-EP and QFN (WF-Type) pinouts
3.2 Pin definitions
Table 2. 33978 pin definitions
Pin number
SOIC
Pin number
QFN Pin name Pin function Formal name Definition
129 GND Ground Ground Ground for logic, analog
230 MOSI Input/SPI SPI Slave In SPI control data input pin from the MCU
331 SCLK Input/SPI Serial Clock SPI control clock input pin
432 CS_B Input/SPI Chip Select SPI control chip select input pin
5 – 8
25 – 28
1 - 4
21 - 24
S P 0 – 3
S P 4 – 7 Input Programmable
S w i t c h e s 0 – 7 Switch to programmable input pins (SB or SG)
9 – 15,
18 – 24
5 - 11
14 - 20
SG0 – 6,
SG7 –13 Input Switch-to-Ground
Inputs 0 – 13 Switch-to-ground input pins
16 12 VBATP Power Battery Input Battery supply input pin. Pin requires external reverse battery
protection
17 13 WAKE_B Input/Output Wake-up Open drain wake-up output. Designed to control a power supply
enable pin. Input used to allow a wake-up from an external event.
29 25 INT_B Input/Output Interrupt
Open-drain output to MCU. Used to indicate an input switch change
of state. Used as an input to allow wake-up from LPM via an external
INT_B falling event.
30 26 AMUX Output Analog Multiplex Output Analog multiplex output.
31 27 VDDQ Input Voltage Drain Supply 3.3 V/ 5.0 V supply. Sets SPI communication level for the MISO driver
and I/O level buffer
MISO
1
SP7
SP6
SP5
SP4
SG13
SG12
SG11
SG10
SG9
SG7
WAKE_B
SG8
INT_B
VDDQ
AMUX
GND
SP0
SP1
SP2
SP3
SG0
SG1
SG2
SG3
SG4
SG6
VBATP
SG5
CS_B
MOSI
SCLK
8
9
10
11
12
13
14
15
16
3
4
5
6
7
2
32
25
24
23
22
21
20
19
18
17
30
29
28
27
26
31
Exposed Pad
EK Suffix
Only
Transparent Top View
1
2
3
4
5
6
7
8
9 10111213141516
32 31 30 29 28 27 26 25
24
23
22
21
20
19
18
17
SP0
SP1
SP2
SP3
SG0
SG1
SG2
SG3
SG4
SG5
SG6
VBATP
WAKE_B
SG7
SG8
SG9
SP7
SP6
SP5
SP4
SG13
SG12
SG11
SG10
CS_B
SCLK
MOSI
GND
MISO
VDDQ
AMUX
INT_B
NXP Semiconductors 6
33978
32 28 MISO Output/SPI SPI Slave Out Provides digital data from the 33978 to the MCU.
EP Ground Exposed Pad It is recommended that the exposed pad is terminated to GND (pin 1)
and system ground.
Table 2. 33978 pin definitions (continued)
Pin number
SOIC
Pin number
QFN Pin name Pin function Formal name Definition
7NXP Semiconductors
33978
4 General product characteristics
4.1 Maximum ratings
Table 3. Maximum ratings
All voltages are with respect to ground unless otherwise noted. Exceeding these ratings may cause a malfunction or permanent damage
to the device.
Symbol Description (rating) Min. Max. Unit Notes
Electrical ratings
VBATP Battery Voltage -0.3 40 V
VDDQ Supply Voltage -0.3 7.0 V
CS_B, MOSI,
MISO, SCLK SPI Inputs/Outputs -0.3 7.0 V
SGx, SPx Switch Input Range -14(4) 38 V
AMUX AMUX -0.3 7.0 V
INT_B INT_B -0.3 7.0 V
WAKE_B WAKE_B -0.3 40 V
VESD1-2
VESD1-3
VESD3-1
VESD2-1
VESD2-2
ESD Voltage
• Human Body Model (HBM) (VBATP versus GND)
MC33978 and MC34978
MC33978A and MC34978A
• Human Body Model (HBM) (All other pins)
• Machine Model (MM)
• Charge Device Model (CDM) (Corners pins)
• Charge Device Model (CDM) (All other pins)
±2000
±4000
±2000
±200
±750
±500
V(5)
VESD5-3
VESD5-4
VESD6-1
VESD6-2
Contact Discharge
• VBATP(8)
• WAKE_B (series resistor 10 kΩ)
• SGx and SPx pins with 100 nF capacitor (100 Ω series R) based on external
protection performance(7)
• SGx and SPx pins with 100 nF capacitor (50 Ω series R)
±8000
±8000
±15000
±8000
V(6)
Notes
4. Minimum value of -18 V is guaranteed by design for switch input voltage range (SGx, SPx).
5. ESD testing is performed in accordance AEC Q100, with the Human Body Model (HBM) (CZAP = 100 pF, RZAP = 1500 Ω), the Machine Model
(MM) (CZAP = 200 pF, RZAP = 0 Ω), and the Charge Device Model (CDM).
6. CZAP = 330 pF, RZAP = 2.0 kΩ (Powered and unpowered) / CZAP = 150 pF, RZAP = 330 Ω (Unpowered)
7. ±15000V capability in powered condition, ±8000V in all other conditions.
8. External component requirements at system level:
Cbulk = 100uF aluminum electrolytic capacitor
Cbypass= 100nF ±37 % ceramic capacitor
Reverse blocking diode from Battery to VBATP (0.6 V < VF < 1 V). See Figure 23, Typical application diagram.
NXP Semiconductors 8
33978
4.2 Thermal characteristics
Table 4. Thermal ratings
All voltages are with respect to ground unless otherwise noted. Exceeding these ratings may cause a malfunction or permanent damage
to the device.
Symbol Description (rating) Min. Max. Unit Notes
Thermal ratings
TA
TJ
Operating Temperature
• Ambient
•Junction
-40
-40
125
150
°C
TSTG Storage Temperature -65 150 °C
TPPRT Peak Package Reflow Temperature During Reflow – – °C
Thermal resistance
RΘJA
Junction-to-Ambient, Natural Convection, Single-Layer Board
• 32 SOIC-EP
• 32 QFN
79
94
°C/W (9),(10)
RΘJB
Junction-to-Board
• 32 SOIC-EP
• 32 QFN
9.0
12
°C/W (11)
RΘJC
Junction-to-Case (Bottom)
• 32 SOIC-EP
• 32 QFN
3.0
2.0
°C/W (12)
ΨJT
Junction-to-Package (Top), Natural convection
• 32 SOIC-EP
• 32 QFN
11
2.0
°C/W (13)
Package dissipation ratings
TSD
Thermal Shutdown
• 32 SOIC-EP
• 32 QFN
155 185 °C
TSDH
Thermal Shutdown Hysteresis
• 32 SOIC-EP
• 32 QFN
3.0 15 °C
Notes
9. Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance, mounting site (board) temperature, ambient
temperature, air flow, power dissipation of other components on the board, and board thermal resistance.
10. Per JEDEC JESD51-2 with natural convection for horizontally oriented board. Board meets JESD51-9 specification for 1s or 2s2p board,
respectively.
11. Thermal resistance between the die and the printed circuit board per JEDEC JESD51-8. Board temperature is measured on the top surface of the
board near the package.
12. Thermal resistance between the die and the solder pad on the bottom of the package based on simulation without any interface resistance.
13. Thermal characterization parameter indicating the temperature difference between package top and the junction temperature per JEDEC JESD51-
2. When Greek letters are not available, the thermal characterization parameter is written as Psi-JT.
9NXP Semiconductors
33978
4.3 Operating conditions
This section describes the operating conditions of the device. Conditions apply to the following data, unless otherwise noted.
4.4 Electrical characteristics
4.4.1 Static electrical characteristics
Table 5. Operating conditions
All voltages are with respect to ground unless otherwise noted. Exceeding these ratings may cause a malfunction or permanent damage
to the device.
Symbol Ratings Min. Max. Unit Notes
VBATP Battery Voltage 4.5 36 V
VDDQ Supply Voltage 3.0 5.25 V
CS_B, MOSI,
MISO, SCLK SPI Inputs / Outputs 3.0 5.25 V
SGx, SPx Switch Input Range -1.0 36 V
AMUX, INT_B AMUX, INT_B 0.0 5.25 V
WAKE_B WAKE_B 0.0 36 V
Table 6. Static electrical characteristics
TA = - 40 °C to +125 °C, VDDQ = 3.1 V to 5.25 V, VBATP = 6.0 V to 28.0 V, unless otherwise noted.
Symbol Characteristic Min. Typ. Max. Units Notes
Power input
VBATP(POR)
VBATP Supply Voltage POR
• VBATP Supply Power on Reset voltage. 2.7 3.3 3.8 V
VBATPUV VBATP Undervoltage Rising Threshold — 4.3 4.5 V
VBATPUVHYS VBATP Undervoltage Hysteresis 250 — 500 mV
VBATPOV VBATP Overvoltage Rising Threshold 32 — 37 V
VBATPOVHYS VBATP Overvoltage Hysteresis 1.5 — 3.0 V
IBAT(ON)
VBATP Supply Current
• All switches open, Normal mode, Tri-state disabled (all channels) —7.012mA
IBATP,IQ,LPM,P
IBATP,IQ,LPM,F
VBATP Low-power Mode Supply Current (polling disabled)
• Parametric VBATP, 6.0 V < VBATP < 28 V
• Functional Low VBATP, 4.5 V < VBATP < 6.0 V
—
—
—
—
40
40
µA
IPOLLING,IQ
VBATP Polling Current
• Polling 64 ms, 11 inputs of wake enabled ——20µA
(14)
IVDDQ,NORMAL
Normal mode (IVDDQ)
•SCLK, MOSI, WakeB = 0 V, CS_B, INT_B =VDDQ, no SPI
communication, AMUX selected no input
— — 500 uA
IVDDQ,LPM
Logic Low-power mode Supply Current
• SCLK, MOSI = 0 V, CS_B, INT_B, WAKE_B = VDDQ, no SPI
communication
——10µA
VGNDOFFSET
Ground Offset
• Ground offset of Global pins to IC ground -1.0 — 1.0 V
VDDQUV VDDQ Undervoltage Falling Threshold 2.2 — 2.8 V
VDDQUVHYS VDDQ Undervoltage Hysteresis 150 — 350 mV
NXP Semiconductors 10
33978
Switch input
ILEAKSG_GND
Leakage (SGx/SPx pins) to GND
• Inputs tri-stated, analog mux selected for each input, voltage at
SGx = VBATP
——2.0μA
ILEAKSG_BAT
Leakage (SGx/SPx pins) to Battery
• Inputs tri-stated, analog mux selected for each input, voltage at
SGx = GND
——2.0μA
ISUSSG
SG Sustain current / Mode 0 Wetting current
• VBATP 6.0 to 28 V 1.6 2.0 2.4 mA
ISUSSGLV
SG Sustain current / Mode 0 Wetting current LV
• VBATP 4.5 V to 6.0 V 1.0 — 2.4 mA (15)
ISUSSB SB Sustain current / Mode 0 Wetting current 1.75 2.2 2.85 mA
IWET
Wetting current level (SG & SB)
• Mode 1 = 6mA
• Mode 2 = 8mA
• Mode 3 = 10mA
• Mode 4 = 12mA
• Mode 5 = 14mA
• Mode 6 = 16mA
• Mode 7 = 20mA
—
6
8
10
12
14
16
20
—mA
IWETSG
SG wetting current tolerance
• Mode 1 to 7 -10 — 10 %
IWETSGLV
SG wetting current tolerance LV (VBATP 4.5 to 6.0V)(15)
• Mode 1 = 6mA
• Mode 2 = 8mA
• Mode 3 = 10mA
• Mode 4 = 12mA
• Mode 5 = 14mA
• Mode 6 = 16mA
• Mode 7 = 20mA
2.0
2.0
2.0
2.0
2.0
2.0
2.0
—
—
—
—
—
—
—
6.6
8.8
11.0
13.2
15.4
17.6
22.0
mA
IWETSB
SB wetting current tolerance
• Mode 1 to 7 -20 — 20 %
IMATCH(SUS) Sustain Current Matching Between Channels — — 10 % (16), (17)
IMATCH(WET) Wetting Current Matching Between Channels — — 6.0 % (18), (19)
VICTHR Switch Detection Threshold 3.7 4.0 4.3 V (20)
VICTHRLV
Switch Detection Threshold Low Battery
• VBATP 4.5 V to 6.0 V
0.55 *
VBATP
—4.3 V
VICTHRLPM Switch Detection Threshold Low-power Mode (SG only) 100 — 300 mV (21)
VICTHRH Switch Detection Threshold Hysteresis (4.0 V threshold) 80 — 300 mV
VICTH2P5
Input Threshold 2.5 V,
• Used for Comp Only and for AMUX Hardwired Select (SG1/2/3) 2.0 2.5 3.0 V
IACTIVEPOLLSG
Low-power Mode Polling Current SG
• VBATP 4.5 V to 28 V 0.7 1.0 1.44 mA
IACTIVEPOLLSB Low-power Mode Polling Current SB 1.75 2.2 2.85 mA
Table 6. Static electrical characteristics (continued)
TA = - 40 °C to +125 °C, VDDQ = 3.1 V to 5.25 V, VBATP = 6.0 V to 28.0 V, unless otherwise noted.
Symbol Characteristic Min. Typ. Max. Units Notes
11 NXP Semiconductors
33978
Digital interface
IHZ Tri-state Leakage Current (MISO)
• VDDQ = 0.0 to VDDQ -2.0 — 2.0 μA
VINLOGIC
Input Logic Voltage Thresholds
• SI, SCLK, CS_B, INT_B
VDDQ *
0.25 —V
DDQ * 0.7 V
VINLOGICHYS
Input Logic Hysteresis
• SI, SCLK, CS_B, INT_B 300 — — mV
VINLOGICWAKE Input Logic Voltage Threshold WAKE_B 0.8 1.25 1.7 V
VINWAKEBHYS Input Logic Voltage Hysteresis WAKE_B 200 — 800 mV
ISCLK, IMOSI
SCLK / MOSI Input Current
• SCLK / MOSI = 0 V -3.0 — 3.0 µA
ISCLK, IMOSI
SCLK / MOSI Pull-down Current
• SCLK / MOSI = VDDQ 30 — 100 µA
ICS_BH
CS_B Input Current
• CS_B = VDDQ -10 — 10 µA
RCS_BL
CS_B Pull-up Resistor to VDDQ
• CS_B = 0.0 V 40 125 270 kΩ
VOHMISO
MISO High-side Output Voltage
•I
OHMISO = -1.0 mA VDDQ – 0.8 — VDDQ V
VOLMISO
MISO Low-side Output Voltage
•I
OLMISO = 1.0 mA ——0.4V
CIN Input Capacitance on SCLK, MOSI, Tri-state MISO (GBD) — — 20 pF
Analog MUX output
VOFFSET
Input Offset Voltage When Selected as Analog
• EK suffix (SOICW)
• ES suffix (QFN at TA = -40 °C to 25 °C)
-10
-15
—
—
10
15
mV (22)
VOLAMUX
Analog Operational Amplifier Output Voltage
•Sink 1.0 mA ——50mV
VOHAMUX
Analog Operational Amplifier Output Voltage
• Source 1.0 mA VDDQ – 0.1 — — V
AMUX selectable outputs
Temp-Coeff Chip Temperature Sensor Coefficient — 8.0 — mV/°C
VBATSNSACC
Battery Sense (SG5 config) Accuracy
• Battery voltage (SG5 input) divided by 6
• Accuracy over full temperature range
-5.0 — 5.0 %
VBATSNSDIV
Divider By 6 coefficient accuracy
• Offset over operating voltage range (VBATP=6.0 V to 28 V) -3.0 — 3.0 % (23)
Table 6. Static electrical characteristics (continued)
TA = - 40 °C to +125 °C, VDDQ = 3.1 V to 5.25 V, VBATP = 6.0 V to 28.0 V, unless otherwise noted.
Symbol Characteristic Min. Typ. Max. Units Notes
NXP Semiconductors 12
33978
INT_B
VOLINT
INT_B Output Low Voltage
•I
OUT = 1.0 mA —0.20.5 V
VOHINT
INT_B Output High Voltage
• INT_B = Open-circuit VDDQ – 0.5 — VDDQ V
RPU Pull-up Resistor to VDDQ 40 125 270 kΩ
ILEAKINT_B Leakage Current INT_B
• INT_B pulled up to VDDQ ——1.0µA
Temperature limit
tFLAG
Temperature Warning
• First flag to trip 105 120 135 °C
tLIM Temperature Monitor 155 — 185 °C (24)
tLIM(HYS) Temperature Monitor Hysteresis 5.0 — 15 °C (24)
WAKE_B
RWAKE_B(RPU) WAKE_B Internal pull-up Resistor to VDDQ 40 125 270 kΩ
VWAKE_B(VOH)
WAKE_B Voltage High
• WAKE_B = Open-circuit VDDQ -1.0 — VDDQ V
VWAKE_B(VOL)
WAKE_B Voltage Low
• WAKE_B = 1.0 mA (RPU to VBATP = 16 V) ——0.4V
IWAKE_BLEAK
WAKE_B Leakage
• WAKE_B pulled up to VBATP = 16 V through 10 kΩ——1.0µA
Notes
14. Guaranteed by design
15. During low voltage range operation SG wetting current may be limited when there is not enough headroom between VBATP and SG pin voltage.
16. (ISUS(MAX)– ISUS(MIN)) X 100/ISUS(MIN)
17. Sustain current source (SGs only)
18. (IWET(MAX) – IWET(MIN)) X 100/IWET(MIN)
19. Wetting current source (SGs only)
20. The input comparator threshold decreases when VBATP ≤ 6.0 V.
21. SP (as SB) only use the 4.0 V VICTHR for LPM wake-up detection.
22. For applications requiring a tight AMUX offset through the whole operating range, it is recommended to use the MC33978AEK or MC34978AEK
(SOICW package) variant.
23. Calibration of divider ratio can be done at VBAT = 12 V, 25 °C to achieve a higher accuracy. See Figure 4 for AMUX offset linearity waveform
through the operating voltage range.
24. Guaranteed by characterization in the Development Phase, parameter not tested.
Table 6. Static electrical characteristics (continued)
TA = - 40 °C to +125 °C, VDDQ = 3.1 V to 5.25 V, VBATP = 6.0 V to 28.0 V, unless otherwise noted.
Symbol Characteristic Min. Typ. Max. Units Notes
13 NXP Semiconductors
33978
4.4.2 Dynamic electrical characteristics
Table 7. Dynamic electrical characteristics
TA = -40 °C to +125 °C. VDDQ = 3.1 V to 5.25 V, VBATP = 6.0 V to 28 V, unless otherwise specified. All SPI timing is performed with a
100 pF load on MISO, unless otherwise noted.
Symbol Parameter Min.Typ. Max. Units Notes
General
tACTIVE
POR to Active time
• Undervoltage to Normal mode 250 340 450 µs
Switch input
tPULSE(ON)
Pulse Wetting Current Timer
• Normal mode 17 20 23 ms
tINT-DLY
Interrupt Delay Time
• Normal mode — — 18.5 µs
tPOLLING_TIMER
Polling Timer Accuracy
• Low-power mode ——15%
tINT-TIMER
Interrupt Timer Accuracy
• Low-power mode ——15%
tACTIVEPOLLSGTI
ME
Tactivepoll Timer SG 49.5 58 66.5 µs
tACTIVEPOLLSBTI
ME
Tactivepoll Timer SB
• SBPOLLTIME=0
• SBPOLLTIME=1
1.0
49.5
1.2
58
1.4
66.5
ms
µs
tGLITCHTIMER
Input Glitch Filter Timer
• Normal mode 5.0 — 18 µs
tDEBOUNCE
LPM Debounce Additional Time
• Low-power mode 1.0 1.2 1.4 ms
AMUX output
AMUXVALID
AMUX Access Time (Selected Output to Selected Output)
• CMUX = 1.0 nF, Rising edge of CS_B to selected —(26) — μs
AMUXVALIDTS
AMUX Access Time (Tristate to ON)
• CMUX = 1.0 nF, Rising edge of CS_B to selected ——20μs
Oscillator
OSCTOLLPM Oscillator Tolerance at 192 kHz in Low-power Mode -15 — 15 %
OSCTOLNOR Oscillator Tolerance Normal Mode at 4.0 MHz -15 — 15 %
Interrupt
INTPULSE INT Pulse Duration
• Interrupt occurs or INT_B request 90 100 110 µs
SPI interface
fOP Transfer Frequency — — 8.0 MHz
tSCK
SCLK Period
•Figure 7 - 1 160 — — ns
tLEAD
Enable Lead Time
•Figure 7 - 2 140 — — ns
tLAG
Enable Lag Time
•Figure 7 - 3 50 — — ns
tSCKHS
SCLK High Time
•Figure 7 - 4 56 — — ns
NXP Semiconductors 14
33978
SPI interface (continued)
tSCKLS
SCLK Low Time
•Figure 7 - 5 56 — — ns
tSUS
MOSI Input Setup Time
•Figure 7 - 6 16 — — ns
tHS
MOSI Input Hold Time
•Figure 7 - 7 20 — — ns
tA
MISO Access Time
•Figure 7 - 8 — — 116 ns
tDIS
MISO Disable Time (25)
•Figure 7 - 9 — — 100 ns
tVS
MISO Output Valid Time
•Figure 7 - 10 — — 116 ns
tHO
MISO Output Hold Time (No cap on MISO)
•Figure 7 - 11 20 — — ns
tRO
Rise Time
•Figure 7 - 12 — — 30 ns (25)
tFO
Fall Time
•Figure 7 - 13 — — 30 ns (25)
tCSN
CS_B Negated Time
•Figure 7 - 14 500 — — ns
WAKE-UP
tCSB_WAKEUP LPM mode wake-up time triggered by edge of CS_B — 755 1000 µs (27)
Notes
25. Guaranteed by characterization.
26. AMUX settling time to be within the 10 mV offset specification. AMUXVALID is dependant of the voltage step applied on the input SGx/SPx pin or
the difference between the first and second channel selected as the multiplexed analog output. See Figure 9 for a typical AMUX access time VS
voltage step waveform.
27. The parameter is guaranteed at VBATP = 4.5 V to 28 V.
Table 7. Dynamic electrical characteristics (continued)
TA = -40 °C to +125 °C. VDDQ = 3.1 V to 5.25 V, VBATP = 6.0 V to 28 V, unless otherwise specified. All SPI timing is performed with a
100 pF load on MISO, unless otherwise noted.
Symbol Parameter Min. Typ. Max. Units Notes
15 NXP Semiconductors
33978
Figure 4. Divide by 6 coefficient accuracy
Figure 5. Glitch filter and interrupt delay timers
Figure 6. Interrupt pulse timer
5.96
5.97
5.98
5.99
6
6.01
6.02
6.03
6.04
6 7 8 9 10111213141516171819202122232425262728
VBATP (Volts)
Divide By 6 Coefficient Accuracy
25°C
Divider factor
LPM CLK
SG_Pin
Input Glitch
filter timer
INT_B
500ns
tglitchTIMER
tINT- DLY
LPM CLK
SG_Pin
INT_B tINT- DLY INTPulse
NXP Semiconductors 16
33978
Figure 7. SPI timing diagram
Figure 8. MISO loading for disable time measurement
Figure 9. AMUX access time waveform
SCLK
6
MSB IN
CARE
LSB IN
DON'T
MISO
MOSI
11
MSB OUT DATA LSB OUT
2
3
4
5
810
7
DATA
9
14
12 13
1
CSb
1kohm
VDDQ
MISO
1kohm
+5.0 V
1.0 V
4.0 V
0 V
MISO
9
CS_B
0
50
100
150
200
250
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Step Size (mV)
AMUX Access Tim
e
Settling time (us)
AMUX settling time vs voltage step
17 NXP Semiconductors
33978
5 General description
The 33978 is designed to detect the closing and opening of up to 22 switch contacts. The switch status, either open or closed, is
transferred to the microprocessor unit (MCU) through a serial peripheral interface (SPI). Individually selectable input currents are available
in Normal and Low-power (LPM) modes, as needed for the application.
It also features a 24-to-1 analog multiplexer for reading inputs as analog. The analog input signal is buffered and provided on the AMUX
output pin for the MCU to read. A battery and temperature monitor are included in the IC and available via the AMUX pin.
The 33978 device has two modes of operation, Normal and Low-power mode (LPM). Normal mode allows programming of the device and
supplies switch contacts with pull-up or pull-down current as it monitors the change of state of switches. The LPM provides low quiescent
current, which makes the 33978 ideal for automotive and industrial products requiring low sleep-state currents.
5.1 Features
• Fully functional operation from 4.5 V to 36 V
• Full parametric operation from 6.0 V to 28 V
• Low-power mode current IBATP = 30 μA and IDDQ = 10 μA
• 22 Switch detection channels
• 14 Switch-to-Ground (SG) inputs
• Eight Programmable switch (SP) inputs
• Switch-to-Ground (SG) or Switch-to-Battery (SB)
• Operating switch input voltage range from -1.0 V to 36 V
• Selectable wetting current (2, 6, 8, 10, 12, 14, 16, or 20 mA)
• Programmable wetting operation (Pulse or Continuous)
• Selectable wake-up on change of state
• 24 to 1 Analog Multiplexer
• Buffered AMUX output from SG/SP channels
• Integrated divider by 6 on SG5 for battery voltage sensing
• Integrated die temperature sensing through AMUX output
• Two or three pin hardwire AMUX selection.
• Active interrupt (INT_B) on change-of-switch state
• Direct MCU Interface through 3.3 V / 5.0 V SPI protocol
NXP Semiconductors 18
33978
5.2 Functional block diagram
Figure 10. Functional block diagram
Logic and Control
SG0 – SG13 SP0 – SP7
Bias & References
WAKE_B I/O INT_B I/O
33978 Functional Internal Block Diagram
SPI Serial Communication & Registers
Switch Status Detection
Fault Detection and Protection
4.0 V SW detection reference.
OV Detection
Over Temperature
Protection
1.25 V internal Bandgap
VBATP UV detect
Input Power
VBATP
Battery Supply
VDDQ
Logic Supply
192 kHz
LPM Oscillator
4.0 MHz
Oscillator
SPI Error detect
HASH error detect
Switch to Ground (SG)
Only
Switch to Ground (SG)
Switch to Battery (SB)
Selectable Wetting Current Level
24 to 1 SPI AMUX select
Analog Multiplexer (AMUX)
Battery Voltage sensing (divided by 6 )
Die Temperature Sensing
Modes of Operation
Normal Mode Low Power Mode
Pulse/Continuous Wetting Current
8 x Programmable Switch
14 x Switch to Ground
Programmable Polling/
Interrupt Time
SPI communication/
Switch status read
Hardwire selectable
SPx/SGx Inputs to AMUX
19 NXP Semiconductors
33978
6 General IC functional description
The 33978 device interacts with many connections outside the module and near the end user. The IC detects changes in switch state and
reports the information to the MCU via the SPI protocol. The input pins generally connected to switches located outside the module and
in proximity to battery in car harnesses. Consequently, the IC must have some external protection including an ESD capacitor and series
resistors, to ensure the energy from the various pulses are limited at the IC.
The IC requires a blocking diode be used on the VBATP pin to protect from a reverse battery condition. The inputs are capable of surviving
reverse battery without a blocking diode and also contain an internal blocking diode from the input to the power supply (VBATP), to ensure
there is no backfeeding of voltage/current into the IC, when the voltage on the input is higher than the VBATP pin.
6.1 Battery voltage ranges
The 33978 device operates from 4.5 V ≤ VBATP ≤ 36 V and is capable to withstand up to 40 V. The IC operates functionally from
4.5 V < VBATP < 6.0 V, but with degraded parametrics values. Voltages in excess of 40 V must be clamped externally in order to protect
the IC from destruction. The VBATP pin must be isolated from the main battery node by a diode.
6.1.1 Load dump (overvoltage)
During load dump the 33978 operates properly up to the VBATP overvoltage. Voltages greater than load dump (~32 V) causes the current
sources to be limited to ~2.0 mA, but the register values are maintained. Upon leaving this overvoltage condition, the original setup is
returned and normal operation begins again.
6.1.2 Jump start (double battery)
During a jump start (double battery) condition, the device functions normally and meets all the specified parametric values. No internal
faults are set and no abnormal operation noted as a result of operating in this range.
6.1.3 Normal battery range
The normal voltage range is fully functional with all parametrics in the given specification.
6.1.4 Low-voltage range (degraded parametrics)
In the VBATP range between 4.5 V to 6.0 V the 33978 functions normally, but has some degraded parametric values. The SPI functions
normally with no false reporting. The degraded parameters are noted in Table 6 and Table 7. During this condition, the input comparator
threshold is reduced from 4.0 V and remain ratiometrically adjusted, according to the battery level.
6.1.5 Undervoltage lockout
During undervoltage lockout, the MISO output is tri-stated to avoid any data from being transmitted from the 33978. Any CS_B pulses are
ignored in this voltage range. If the battery enters this range at any point (even during a SPI word), the 33978 ignores the word and enters
lockout mode. A SPI bit register is available to notify the MCU that the 33978 has seen an undervoltage lockout condition once the battery
is high enough to leave this range.
6.1.6 Power on reset (POR) activated
The Power on Reset is activated when the VBATP is within the 2.7 V to 3.8 V range. During the POR all SPI registers are reset to default
values and SPI operation is disabled. The 33978 is initialized after the POR is de-asserted. A SPI bit in the device configuration register
is used to note a POR occurrence and all SPI registers are reset to the default values.
6.1.7 No operation
The device does not function and no switch detection is possible.
NXP Semiconductors 20
33978
Figure 11. Battery voltage range
6.2 Power sequencing conditions
The chip uses two supplies as inputs into the device for various usage. The pins are VBATP and VDDQ. The VBATP pin is the power
supply for the chip where the internal supplies are generated and power supply for the SG circuits. The VDDQ pin is used for the I/O buffer
supply to talk to the MCU or other logic level devices, as well as AMUX. The INT_B pin is held low upon POR until the IC is ready to
operate and communicate. Power can be applied in various ways to the 33978 and the following states are possible:
6.2.1 VBATP before VDDQ
The normal condition for operation is the application of VBATP and then VDDQ. The chip begin to operate logically in the default state but
without the ability to drive logic pins. When the VDDQ supply is available the chip is able to communicate correctly. The IC maintains its
logical state (register settings) with functional behavior consistent with logical state. No SPI communications can occur.
6.2.2 VDDQ before VBATP
The VDDQ supply in some cases may be available before the VBATP supply is ready. In this scenario, there is no back feeding current into
the VDDQ pin that could potentially turn on the device into an unknown state. VDDQ is isolated from VBATP circuits and the device is off
until VBATP is applied; when VBATP is available the device powers up the internal rails and logic within tACTIVE time. Communication is
undefined until the tACTIVE time and becomes available after this time frame.
6.2.3 VBATP okay, VDDQ lost
After power up, it is possible that the VDDQ may turn off or be lost. In this case, the chip remains in the current state but is not able to
communicate. After the VDDQ pin is available again, the chip is ready to communicate.
6.2.4 VDDQ okay, VBATP lost
After power up, the VBATP supply could be lost. The operation is consistent as when VDDQ is available before VBATP.
Functional
Normal Mode
Full Parametrics
Overvoltage
No Operation
41 V
37 V
29 V
7.0 V
0 V
5.5 V
Degraded Parametrics
Battery Voltage
(System Level)
Over Voltage
Load Dump
Normal
Battery
Low Battery
Reset
40 V
36 V
28 V
6.0 V
0 V
4.5 V
VBATP
(IC Level)
Undervoltage lockout
4.8 V 3.8 V
POR 2.7 V3.7 V
21 NXP Semiconductors
33978
7 Functional block description
7.1 State diagram
Figure 12. 33978 state diagram
7.1.1 State machine
After power up, the IC enters into the device state machine, as illustrated in Figure 12. The voltage on VBATP begins to power the internal
oscillators and regulator supplies. The POR is based on the internal 2.5 V digital core rail. When the internal logic regulator reaches
approximately 1.8 V (typically 3.3 V on the VBATP node), the IC enters into the UV range. Below the POR threshold, the IC is in RESET
mode where no activity occurs.
OV / OT
Iwet-> Isus
Wake
Event
Normal Mode
Low Power
Mode
Polling
UV
RESET
Run
VBATP > OV
or OT
VBAT too low:
POR
VBATP applied
Detect change in switch
status (opn/close)
SPI CMD
Polling time expires
Polling timer initiates
VBATP <
UV
IC OFF
VBAT applied >
por
Wait 50 μs
Read fuses
VBATP > UV
threshold
Not VBATP > OV
or OT
SPI RESET
command
NXP Semiconductors 22
33978
7.1.2 UV: undervoltage lockout
After the POR circuit has reset the logic, the IC is in undervoltage. In this state, the IC remembers all register conditions, but is in a lockout
mode, where no SPI communication is allowed. The AMUX is inactive and the current sources are off. The user does not receive a valid
response from the MISO, as it is disabled in this state. The chip oscillators (4.0 MHz for most normal mode activities, 192 kHz for LPM,
and limited normal mode functions) are turned on in the UV state. The chip moves to the Read fuses state when the VBATP voltage rises
above the UV threshold (~4.3 V rising). The internal fuses read in approximately 50 μs and the chip enters the Normal mode.
7.1.3 Normal mode
In normal mode, the chip operates as selected in the available registers. Any command may be loaded in normal mode, although not all
(Low-power mode) registers are used in the Normal mode. All the LPM registers must be programmed in Normal mode as the SPI is not
active in LPM. The Normal mode of the chip is used to operate the AMUX, communicate via the SPI, Interrupt the IC, wetting and sustain
currents, as well as the thresholds available to use. The WAKE_B pin is asserted (low) in Normal mode and can be used to enable a power
supply (ENABLE_B). Various fault detections are available in this mode including overvoltage, overtemperature, thermal warning, SPI
errors, and Hash faults.
7.1.4 Low-power mode
When the user needs to lower the IC current consumption, a low-power mode is used. The only method to enter LPM is through a SPI
word. After the chip is in low-power mode, the majority of circuitry is turned off including most power rails, the 4.0 MHz oscillator, and all
the fault detection circuits. This mode is the lowest current consumption mode on the chip. If a fault occurs while the chip is in this mode,
the chip does not see or register the fault (does not report via the SPI when awakened). Some items may wake the IC in this mode,
including the interrupt timer, falling edge of INT_B, CS_B, or WAKE_B (configurable), or a comparator only mode switch detection.
7.1.5 Polling mode
The 33978 uses a polling mode which periodically (selectable in LPM config register) interrogates the input pins to determine in what state
the pins are, and decide if there was a change of state from when the chip was in Normal mode. There are various configurations for this
mode, which allow the user greater flexibility in operation. This mode uses the current sources to pull-up (SG) or down (SB) to determine
if a switch is open or closed. More information is available in section 7.2, “Low-power mode operation".
In the case of a low VBATP, the polling pauses and waits until the VBATP rises out of UV or a POR occurs. The pause of the polling ensures
all of the internal rails, currents, and thresholds are up at the required levels to accurately detect open or closed switches. The chip does
not wake-up in this condition and simply waits for the VBATP voltage to rise or cause a POR.
After the polling ends, the chip either returns to the low-power mode, or enters Normal mode when a wake event was detected. Other
events may wake the chip as well, such as the falling edge of CS_B, INT_B, or WAKE_B (configurable). A comparator only mode switch
detection is always on in LPM or Polling mode, so a change of state for those inputs would effectively wake the IC in Polling mode as well.
If the Wake-up enable bits are disable on all channels (SG and SP) the device will not wake up with a change of state on any of the input
pins; in this case, the device will disable the polling timer to allow the lowest current consumption during low-power mode.
7.2 Low-power mode operation
Low-power mode (LPM) is used to reduce system quiescent currents. LPM may be entered only by sending the Enter Low-power mode
command. All register settings programmed in Normal mode are maintained while in LPM.
The 33978 exits LPM and enter Normal mode when any of the following events occur:
• Input switch change of state (when enabled)
• Interrupt timer expire
• Falling edge of WAKE_B (as set by the device configuration register)
• Falling edge of INT_B (with VDDQ = 5.0 V)
• Falling edge of CS_B (with VDDQ = 5.0 V)
• Power-ON Reset (POR)
The VDDQ supply may be removed from the device during LPM, however removing VDDQ from the device disables a wake-up from falling
edge of INT_B and CS_B. The IC checks the status of VDDQ after a falling edge of WAKE_B (as selected in the device configuration
register), INT_B and CS_B. The IC returns to LPM and does not report a Wake event, if VDDQ is low. If the VDDQ is high, the IC wakes up
and reports the Wake event. In cases where CS_B is used to wake the device, the first MISO data message is not valid.
23 NXP Semiconductors
33978
The LPM command contains settings for two programmable registers: the interrupt timer and the polling timer, as shown in Table 26. The
interrupt timer is used as a periodic wake-up timer. When the timer expires, an interrupt is generated and the device enters Normal mode.
The polling timer is used periodically to poll the inputs during Low-power mode to check for change of states. The tACTIVEPOLL time is the
length of time the part is active during the polling timer to check for change of state. The Low-power mode voltage threshold allows the
user to determine the noise immunity versus lower current levels that polling allows. Figure 14 shows the polling operation.
When polling and Interrupt timer coincide, the Interrupt timer wakes the device and the polling does not occur. When an input is determined
to meet the condition Open (when entering LPM), yet while Open (on polling event) the chip does not continue the polling event for that
input(s) to lower current in the chip (Figure 13 shows SG, SB is logically the same).
Figure 13. Low-power mode polling check
Figure 14. Low-power mode typical timing
Latch
voltage
Compare voltage to initial
(Delta > 0.25 or > 4.0v)
LPM Voltage threshold
(~0.25v)
Polling timer
(64ms def)
Voltage on SG pin
End Polling (current off if
no change detected)
55µs
CS_B
Polling Time
Polling startup
Tactive time
Mode
Normal
LPM
Normal
Go To LPM
64ms (config)
78us
58us
20us
IC Current
330uA
20uA
Load
Current
X * 1mA SG
(2mA SB)
0uA
NXP Semiconductors 24
33978
Figure 15. Low-power mode to normal mode operation
7.3 Input functional block
The SGx pins are switch-to-ground inputs only (pull-up current sources).
The SPx pins are configurable as either switch to ground or switch to battery (pull-up and pull-down current sources).
The input is compared with a 4.0 V (input comparator threshold configurable) reference. Voltages greater than the input comparator
threshold value are considered open for SG pins and closed for SB configuration.
Voltages less than the input comparator threshold value are considered closed for SG pins and open for the SB configurations.
Programming features are defined in the SPI control register definition section of this data sheet.
The input comparator has hysteresis with the thresholds based on the closing of the switch (falling on SG, rising on SB).
The user must take care to keep power conditions within acceptable limits (package is capable of 2.0 W). Using many of the inputs with
continuous wetting current levels causes overheating of the IC and may cause an overtemperature (OT) event to occur.
VBATP
VDDQ
WAKE_B
INT_B
CS_B
SGn
Power – up
Normal Mode
Tri-state
Command
Sleep
Command Sleep Mode Normal
Mode
Sleep
Command Sleep Mode Normal
Mode
Sleep
Command
Wake up from Interrupt
Timer expire
Wake up from
Closed Switch
25 NXP Semiconductors
33978
Figure 16. SG block diagram
6 - 20
mA
2.0
mA
Pre-reg = ~8v
4.0 V ref comparator
Or
250mV Delta V
Or
2.5v Comparator only
To SPI
1.0mA
(LPM)
VBATP
To AMUX
NXP Semiconductors 26
33978
Figure 17. SP block diagram
7.4 Oscillator and timer control functional block
Two oscillators are generated in this block. A 4.0 MHz clock is used in Normal mode only, as well as a Low-power mode 192 kHz clock,
which is on all the time. All timers are generated from these oscillators. The oscillator accuracy is 15 % for both, the 4.0 MHz clock and
the 192 kHz clock. No calibration is needed and the accuracy is over voltage and temperature.
7.5 Temperature monitor and control functional block
The device has multiple thermal limit (tLIM) cells to detect thermal excursions in excess of 155 °C. The tLIM cells from various locations on
the IC are logically ORed together and communicated to the MCU as one tLIM fault. When the tLIM value is seen, the wetting current is
lowered to 2.0 mA until the temperature has decreased beyond the tLIM(HYS) value (the sustain current remains on or as selected). A
hysteresis value of 15 °C exists to keep the device from cycling.
A thermal flag also exists to alert the system to increasing temperatures more than approximately 120 °C.
7.6 WAKE_B control functional block
The WAKE_B pin can operate as an open-drain output or a wake-up input. In the Normal Mode, the WAKE_B pin is LOW. In the Low-
power mode, the WAKE_B pin is pulled HIGH. The WAKE_B pin has an internal pull-up to VDDQ supply with an internal series diode to
allow an external pull-up to VBATP if required.
6 - 20
mA
2.0
mA
Pre-reg
4.0 V ref comparator
To SPI
1.0mA
(LPM)
VBATP
6 - 20
mA
2.0
mA
1.0mA
(LPM)
2
27 NXP Semiconductors
33978
As an input, in Low-power mode with the WAKE_B pin pulled HIGH, when commanded LOW by MCU, the falling edge of WAKE_B places
the MC33978 in Normal mode. In Low-power mode if VDDQ goes low, the WAKE_B pin can still wake the device based on the status of
the WAKE_B bit in the device configuration register, this allows the user to pull the WAKE_B pin up to VBATP such that it can be used in
VDDQ off setup.
As an output, WAKE_B pin can drive either an MCU input or the EnableB of a regulator (possibly for VDDQ). WAKE_B is driven Low during
Normal mode regardless of the state of VDDQ. When the 33978 is in LPM, the WAKE_B pin is released and is expected to be pulled up
internally to VDDQ or externally to VBATP. When a valid wake-up event is detected, the 33978 wakes up from LPM and the WAKE_B is
driven Low (regardless of the state of VDDQ).
7.7 INT_B functional block
INT_B is an input/output pin in the 33978 device to indicate an interrupt event has occurred, as well as receiving interrupts from other
devices when the INT_B pins are wired ORed. The INT_B pin is an open-drain output with an internal pull-up to VDDQ. In Normal mode,
a switch state change triggers the INT_B pin (when enabled). The INT_B pin and INT_B bit in the SPI register are latched on the falling
edge of CS_B. This permits the MCU to determine the origin of the interrupt. When two 33978 devices are used, only the device initiating
the interrupt has the INT_B bit set. The INT_B pin and INTflg bit are cleared 1.0 μs after the falling edge of CS B. The INT_B pin does not
clear with the rising edge of CS_B if a switch contact change has occurred while CS_B was Low.
In a multiple 33978 device system with WAKE_B High and VDDQ on (Low-power mode), the falling edge of INT_B places all 33978s in
Normal mode. The INT_B has the option of a pulsed output (pulsed low for INTpulse duration) or a latched low output. The default case is
the latched low operation; the pulsed option is selectable via the SPI.
An INT_B request by the MCU can be done by a SPI word and results in an INTPULSE of 100 μs duration on the INT_B pin.
The chip causes an INT_B assertion for the following cases:
1. A change of state is detected
2. Interrupt timer expires
3. Any Wake-up event
4. Any faults detected
5. After a POR, the INT_B pin states asserted during startup until the chip is ready to communicate
7.8 AMUX functional block
The analog voltage on switch inputs may be read by the MCU using the analog command (Table 43). Internal to the IC is a 24-to-1 analog
multiplexer. The voltage present on the selected input pin is buffered and made available on the AMUX output pin. The output pin is
clamped to a maximum of VDDQ regardless of the higher voltages present on the input pin. After an input has been selected as the analog,
the corresponding bit in the next MISO data stream is logic [0]. When selecting a channel to be read as analog input, the user can also
set the current level allowed in the AMUX output. Current level can be set to the programmed wetting current for the selected channel or
set to high-impedance as defined in Table 42.
When selecting an input to be sent to the AMUX output, that input is not polled or a wake-up enabled input from Low-power mode. The
user should set the AMUX to “No input selected” or “Temp diode” before entering Low-power mode. The AMUX pin is not active during
Low-power mode. The SG5 pin can also be used as a VBATP sense pin. An internal resistor divider of 1/6 is provided for conditioning the
VBATP higher voltage to a level within the 0 V to VDDQ range.
Besides the default SPI input selection method, the AMUX has two hardwire operation such that the user can select an specific input
channel by physically driving the SG1, SG2 or SG3 pin (HW 3-bit), or by driving the SG1 and SG2 pins (HW 2-bit) as shown in Table 9
and Table 10. When using the AMUX hardwired options, the SG1, SG2, and SG3 inputs use a 2.5 V input voltage threshold to read a
logic 0 or logic 1.
Table 8 shows the AMUX selection methods configurable by the Aconfig0 and Aconfig1 bits in the Device Configuration register.
Table 8. AMUX selection method
Aconfig1 Aconfig0 AMUX Selection method
0 0 SPI (def)
0 1 SPI
10 HW 2-bit
11 HW 3-bit
NXP Semiconductors 28
33978
Since the device is required to meet the ±1.0 V offset with ground, it is imperative that the user bring the sensor ground back to the 33978
when using the AMUX for accurate measurements to ensure any ground difference does not impact the device operation.
7.9 Serial peripheral interface (SPI)
The 33978 contains a serial peripheral interface consisting of Serial Clock (SCLK), Serial Data Out (MISO), Serial Data In (MOSI), and
Chip Select Bar (CS_B). The SPI interface is used to provide configuration, control, and status functions; the user may read the registers
contents as well as read some status bits of the IC. This device is configured as an SPI slave.
All SPI transmissions to the 33978 must be done in exact increments of 32 bits (modulo 0 is ignored as well). The 33978 contains a data
valid method via SCLK input to keep non-modulo-32 bit transmissions from being written into the IC. The SPI module also provides a daisy
chain capability to accommodate MOSI to MISO wrap around (see Figure 21).
The SPI registers have a hashing technique to ensure that the registers are consistent with the programmed values. If the hashed value
does not match the register status, a SPI bit is set as well as an interrupt to alert the MCU to this issue.
7.9.1 Chip select low (CS_B)
The CS_B input selects this device for serial transfers. On the falling edge of CS_B, the MISO pin is released from tri-state mode, and all
status information are latched in the SPI shift register. While CS_B is asserted, register data is shifted in the MOSI pin and shifted out the
MISO pin on each subsequent SCLK. On the rising edge of CS_B, the MISO pin is tri-stated and the fault register reloaded (latched) with
the current filtered status data. To allow sufficient time to reload the fault registers, the CS_B pin must remain low for a minimum of tCSN
prior to going high again.
The CS_B input contains a pull-up current source to VDDQ to command the de-asserted state should an open-circuit condition occur.
This pin has threshold compatible voltages allowing proper operation with microprocessors using a 3.3 V to 5.0 V supply.
7.9.2 Serial clock (SCLK)
The SCLK input is the clock signal input for synchronization of serial data transfer. This pin has a threshold compatible voltages allowing
proper operation with microprocessors using a 3.3 V to 5.0 V supply.
When CS_B is asserted, both the Master Microprocessor and this device latch input data on the rising edge of SCLK. The SPI master
typically shifts data out on the falling edge of SCLK, while this device shifts data out on the rising edge of SCLK, to allow more time to
drive the MISO pin to the proper level.
Table 9. AMUX hardware 3-bit
Pins [SG3, SG2, SG1] Output of AMUX
000 SG0
001 SG5
010 SG6
011 SG7
100 SG8
101 SG9
110 Temperature Diode
111 Battery Sense
Table 10. AMUX hardware 2-bit
Pins [SG2, SG1] Output of AMUX
00 SG0
01 SG5
10 SG6
11 SG7
29 NXP Semiconductors
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This input is used as the input for the modulo-32 bit counter validation. Any SPI transmissions which are NOT exact multiples of 32 bits
(i.e. clock edges) is treated as an illegal transmission. The entire frame is aborted and no information is changed in the configuration or
control registers.
7.9.3 Serial data output (MISO)
The MISO output pin is in a tri-state condition when CS_B is negated. When CS_B is asserted, MISO is driven to the state of the MSB of
the internal register and start shifting out the requested data from the MSB to the LSB. This pin supplies a “rail to rail” output, depending
on the voltage at the VDDQ pin.
7.9.4 Serial data input (MOSI)
The MOSI input takes data from the master microprocessor while CS_B is asserted. The MSB is the first bit of each word received on
MOSI and the LSB is the last bit of each word received on MOSI. This pin has threshold level compatible input voltages allowing proper
operation with microprocessors using a 3.3 V to 5.0 V (VDDQ) supply.
Figure 18. First SPI operation (after POR)
Figure 19. SPI write operation
MOSI/
SCLK
MISO
Control word Configure words
31 24252627282930 23 0122
Fault Status
INTflg
SG/SP input status
21 23
20 ...
CS_B
Switch Status Register
MOSI/
SCLK
MISO
Control word Configure word
31 24252627282930 23 0122
Previous command data
21 23
20 ...
Previous Address
CS_B
MISO
31 24252627282930 23 0122
Configure Word
21 23
20 ...
Control Word
MOSI/
SCLK
Next Control word Next Configure words
CS_B
NXP Semiconductors 30
33978
Figure 20. SPI read operation
Figure 21. Daisy chain SPI operation
MOSI/
SCLK
MISO
Control word (READ) DON’T CARE
31 24252627282930 23 0122
Previous command data
21 23
20 ...
Previous Address
CS_B
MISO
31 24252627282930 23 0122
Register Data
21 23
20 ...
Control Word (READ)
MOSI/
SCLK
Next Control word Next Configure words
CS_B
- 3rd IC
MISO - 1st IC
MOSI - 2 nd IC
- 3rd IC
MCU MOSI
- 2st IC
- 3rd IC
MOSI - 1st IC
MCU MISO
- 2 nd IC - 1st IC
MOSI - 3rd IC - 2 nd IC - 1st ICDon' t Care
Don' t Care
1st IC
SCLK
DI
DO
2 nd IC
SCLK
DI
DO
3rd IC
SCLK
DI
DO
SCLK
MISO
MISI
MCU
CSb CSb
CSb
CSb
CSb
MISO
MOSI
MISO
MISO MISO MISO
MOSI MOSI
31 NXP Semiconductors
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7.10 SPI control register definition
A 32-bit SPI allows the system microprocessor to configure the 33978 for each input as well as read out the status of each input. The SPI
also allows the Fault Status and INTflg bits to be read via the SPI. The SPI MOSI bit definitions are given in Table 11:
The 32-bit SPI word consists of a command word (8-bit) and three configure words (24-bit). The 8 MSB bits are the command bits that
select what type of configuration is to occur. The remaining 24-bits are used to select the inputs to be configured.
• Bit 31 - 24 = Command word: Use to select what configuration is to occur (example: setting wake-up enable command)
• Bit 23 - 0 = SGn input select word: Use these bits in conjunction with the command word to determine which input is setup.
Configuration registers may be read or written to. To read the contents of a configuration register, send the register address + ‘0’ on the
LSB of the command word; the contents of the corresponding register will be shifted out of the MISO buffer in the next SPI cycle. When
a Read command is sent, the answer (in the next SPI transaction) includes the Register address in the upper byte (see Figure 20).
Table 11. MOSI input register bit definition
Register # Register name Address Rb/W
0SPI check 0 0 0 00000
02/03 Device configuration register 0 0 0 00010/1
04/05 Tri-state SP register 0 0 0 00100/1
06/07 Tri-state SG register 0 0 0 00110/1
08/09 Wetting current level SP register 0 0 0 01000/1
0A/0B Wetting current level SG register 0 0 0 0 01010/1
0C/0D Wetting current level SG register 1 0 0 0 01100/1
16/17 Continuous wetting current SP register 0 0 0 10110/1
18/19 Continuous Wetting Current SG Register 0 0 0 11000/1
1A/1B Interrupt enable SP register 0 0 0 11010/1
1C/1D Interrupt enable SG register 0 0 0 11100/1
1E/1F Low-power mode configuration 0 0 0 11110/1
20/21 Wake-up enable register SP 0 0 1 00000/1
22/23 Wake-up enable register SG 0 0 1 00010/1
24/25 Comparator only SP 0 0 1 00100/1
26/27 Comparator only SG 0 0 1 00110/1
28/29 LPM voltage threshold SP configuration 0 0 1 01000/1
2A/2B LPM voltage threshold SG configuration 0 0 1 01010/1
2C/2D Polling current SP configuration 0 0 1 01100/1
2E/2F Polling current SG configuration 0 0 1 01110/1
30/31 Slow polling SP 0 0 1 10000/1
32/33 Slow polling SG 0 0 1 10010/1
34/35 Wake-up debounce SP 0 0 1 10100/1
36/37 Wake-up debounce SG 0 0 1 10110/1
39 Enter low-power mode 0 0 1 11001
3A/3B AMUX control register 0 0 1 11010/1
3E Read switch status 0 0 1 11110
42 Fault status register 0 1 0 00010
47 Interrupt request 0 1 0 00111
49 Reset register 0 1 0 01001
NXP Semiconductors 32
33978
Read example:
• Send 0x0C00_0000 Receive: 8000_0000 (for example after a POR)
• Send 0x0000_0000 Receive: 0C00_0000 (address + register data)
The first response from the device after a POR event is a Read Status register (0x3Exxxxxx where x is the status of the inputs). This is
the same for exiting the Low-power mode (see Figure 18.).
To write into a configuration register, send the register Address + ‘1’ on the LSB of the command word and the configuration data on the
next 24 bits. The new value of the register will be shifted out of the MISO buffer in the next SPI cycle, along with the register address.
Table 7.10.1 provides a general overview of the functional SPI commands and configuration bits.
Table 12. Functional SPI register map
Commands [31-25] 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Address R/W
SPI check 0000000 0XXXXXXXXXXXXXXXXXXXXXXXX
Device Configuration 0000001 0/1FSINTXXXXXXXX
SBPOLL TIME
VBATP OV Disable
WAKE_B Pull up
IntB_Out
aconfig1
aconfig0
SP7
SP6
SP5
SP4
SP3
SP2
SP1
SP0
Tri-State Enable SP 0000010 0/1FSINTXXXXXXXXXXXXXXSP7SP6SP5SP4SP3SP2SP1SP0
Tri-State Enable SG 0000011 0/1FSINTXXXXXXXXSG13SG12SG11SG10SG9SG8SG7SG6SG5SG4SG3SG2SG1SG0
Wetting Current Level SP 0000100 0/1 SP7[2-0] SP6[2-0] SP5[2-0] SP4[2-0] SP3[2-0] SP2[2-0] SP1[2-0] SP0[2-0]
Wetting Current Level SG 0 0000101 0/1 SG7[2-0] SG6[2-0] SG5[2-0] SG4[2-0] SG3[2-0] SG2[2-0] SG1[2-0] SG0[2-0]
Wetting Current Level SG 1 0000110 0/1FSINTXXXX SG13[2-0] SG12[2-0] SG11[2-0] SG10[2-0] SG9[2-0] SG8[2-0]
Continuous Wetting Current
Enable SP 0001011 0/1FSINTXXXXXXXXXXXXXXSP7SP6SP5SP4SP3SP2SP1SP0
Continuous Wetting Current
Enable SG 0001100 0/1FSINTXXXXXXXXSG13SG12SG11SG10SG9SG8SG7SG6SG5SG4SG3SG2SG1SG0
Interrupt Enable SP 0001101 0/1FSINTXXXXXXXXXXXXXXSP7SP6SP5SP4SP3SP2SP1SP0
Interrupt Enable SG 0001110 0/1FSINTXXXXXXXXSG13SG12SG11SG10SG9SG8SG7SG6SG5SG4SG3SG2SG1SG0
Low-power mode
configuration 0001111 0/1FSINTXXXXXXXXXXXXXXint3int2int2int0poll3poll2poll1poll0
Wake-Up Enable SP 0010000 0/1FSINTXXXXXXXXXXXXXXSP7SP6SP5SP4SP3SP2SP1SP0
Wake-Up Enable SG 0010001 0/1FSINTXXXXXXXXSG13SG12SG11SG10SG9SG8SG7SG6SG5SG4SG3SG2SG1SG0
LPM Comparator Only SP 0010010 0/1FSINTXXXXXXXXXXXXXXSP7SP6SP5SP4SP3SP2SP1SP0
LPM Comparator Only SG 0010011 0/1FSINTXXXXXXXXSG13SG12SG11SG10SG9SG8SG7SG6SG5SG4SG3SG2SG1SG0
LPM Voltage Threshold SP 0010100 0/1FSINTXXXXXXXXXXXXXXSP7SP6SP5SP4SP3SP2SP1SP0
LPM Voltage Threshold SG 0010101 0/1FSINTXXXXXXXXSG13SG12SG11SG10SG9SG8SG7SG6SG5SG4SG3SG2SG1SG0
LPM Polling current config
SP 0010110 0/1FSINTXXXXXXXXXXXXXXSP7SP6SP5SP4SP3SP2SP1SP0
LPM Polling current config
SG 0010111 0/1FSINTXXXXXXXXSG13SG12SG11SG10SG9SG8SG7SG6SG5SG4SG3SG2SG1SG0
LPM Slow Polling SP 0011000 0/1FSINTXXXXXXXXXXXXXXSP7SP6SP5SP4SP3SP2SP1SP0
LPM Slow Polling SG 0011001 0/1FSINTXXXXXXXXSG13SG12SG11SG10SG9SG8SG7SG6SG5SG4SG3SG2SG1SG0
Wake-Up Debounce SP 0011010 0/1FSINTXXXXXXXXXXXXXXSP7SP6SP5SP4SP3SP2SP1SP0
Wake-Up Debounce SG 0011011 0/1FSINTXXXXXXXXSG13SG12SG11SG10SG9SG8SG7SG6SG5SG4SG3SG2SG1SG0
Enter Low-power mode 0011100 1FSINTXXXXXXXXXXXXXXXXXXXXXX
AMUX Channel Select SPI 0011101 0/1FSINTXXXXXXXXXXXXXXXasettasel5asel4asel3asel2asel1asel0
Read Switch Status 0011111 0
FAULT STATUS
INTflg
SP7
SP6
SP5
SP4
SP3
SP2
SP1
SP0
SG13
SG12
SG11
SG10
SG9
SG8
SG7
SG6
SG5
SG4
SG3
SG2
SG1
SG0
Fault Status 0100001 0X
INTflg
X
X
X
X
X
X
X
X
X
X
X
SPI Error
hash fault
X
UV
OV
TempFlag
OT
INT_B wake
WAKE_B
SpiWake
POR
Interrupt Pulse Request 0100011 1FSINTXXXXXXXXXXXXXXXXXXXXXX
Reset 0100100 1XXXXXXXXXXXXXXXXXXXXXXXX
Notes
28. FS = FAULT STATUS (available for reading on MISO return word)
29. INT = INTflg (available for reading on MISO return word)
33 NXP Semiconductors
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7.10.1 SPI check
The MCU may check the communication with the IC by using the SPI Check register. The MCU sends the command and the response
during the next SPI transaction will be 0x123456. The SPI Check command does not return Fault Status or INTflg bit, thus interrupts will
not be cleared.
7.10.2 Device configuration register
The device has various configuration settings that are global in nature. The configuration settings are as follows:
• When the 33978 is in the overvoltage region, a Logic [0] on the VBATP OV bit limits the wetting current on all input channels to 2 mA
and the 33978 will not be able to enter into the Low-power mode. A Logic [1] allows the device to operate normally even in the
overvoltage region. The OV flag will be set when the device enters in the OV region, regardless the value of the VBATP OV bit.
• WAKE_B can be used to enable an external power supply regulator to supply the VDDQ voltage rail. When the WAKE_B VDDQ check
bit is a Logic [0], the WAKE_B pin is expected to be pulled-up internally or externally to VDDQ and VDDQ is expected to go low,
therefore the 33978 does not wake-up on the falling edge of WAKE_B. A Logic [1], assumes the user is using an external pull-up to
VBATP or VDDQ (when VDDQ is not expected to be off) and the IC wakes up on a falling edge of WAKE_B.
• INT_B out is used to select how the INT_B pin operates when an interrupt occurs. The IC is able to pulse low [1] or latch low [0].
• Aconfig[1-0] is used to determine the method of selecting the AMUX output, either a SPI command or using a hardwired setup using
SG[3-1].
• Inputs SP0-7 may be programmable for switch-to-battery or switch-to-ground. These inputs types are defined using the settings
command. To set a SPn input for switch-to-battery, a logic [1] for the appropriate bit must be set. To set a SPn input for switch-to-
ground, a logic [0] for the appropriate bit must be set. The MCU may change or update the programmable switch register via software
at any time in Normal mode. Regardless of the setting, when the SPn input switch is closed a logic [1] is placed in the serial output
response register.
Table 13. SPI check command
Register address RSPI data bits [23 - 0]
[31-25] [24] bits [23 - 16]
0000_000 0 0000_0000
bits [15 - 8]
0000_0000
bits [7 - 0]
0000_0000
MISO return word 0x00123456
NXP Semiconductors 34
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Table 14. Device configuration register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0000_001 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SBPOLL
TIME
VBATP OV
disable
WAKE_B
VDDQ Check INT_B out Aconfig1 Aconfig0
00001000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
11111111
MISO return word bit [23] bit [22] bits [21 - 0]
0000_001[R/W] FAULT
STATUS INTflg Register Data
Table 15. Device configuration bits definition
Bit Functions Default value Description
23-14 Unused 0 Unused
13 SBPOLLTIME 0
Select the polling time for SP channels configured as SB.
• A logic [0] set the active polling timer to 1ms,
• A logic [1] sets the active polling timer to 55 μs.
12 VBATP OV
Disable 0
VBATP Overvoltage protection
• 0 - Enabled
• 1 - Disable
11 WAKE_B
VDDQ Check 1
Enable/Disable WAKE_B to wake-up the device on falling edge when VDDQ is not present.
• 0 - WAKE_B is pulled up to VDDQ (internally and/or externally). WAKE_B is ignored while in LPM if VDDQ
is low.
• 1 - WAKE_B is externally pulled up to VBATP or VDDQ and wakes upon a falling edge of the WAKE_B pin
regardless of the VDDQ status.(VDDQ is not expected to go low)
10 Int_B_Out 0
Interrupt pin behavior
• 0 - INT pin stays low when interrupt occurs
• 1 - INT pin pulse low and return high
9-8 Aconfig(1-0) 00
Configure the AMUX output control method
• 00 - SPI (default)
• 01 - SPI
• 10 - HW 2bit
• 11 - HW 3bit
Refer to section 7.8, “AMUX functional block" for details on 2 and 3 bit hardwire configuration.
7-0 SP7 - SP0 1111_1111
Configure the SP pin as Switch to Battery (SB) or Switch to ground (SG)
• 0 - Switch to Ground
• 1 - Switch to Battery
35 NXP Semiconductors
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7.10.3 Tri-state SP register
The tri-state command is use to set the input nodes as high-impedance (Table 16). By setting the tri-state register bit to logic [1], the input
is high-impedance regardless of the Wetting current setting. The configurable comparator (4.0 V default) on each input remains active.
The MCU may change or update the tri-state register via software at any time in Normal mode. The tri-state register defaults to 1 (inputs
are tri-stated). Any inputs in tri-state is still polled in LPM but the current source is not active during this time. The determination of change
of state occurs at the end of the tACTIVEPOLL and the wake-up decision is made.
7.10.4 Tri-state SG register
The tri-state command is used to set the input nodes as high-impedance (Table 17). By setting the tri-state register bit to logic [1], the
input is high-impedance regardless of the Wetting command setting. The configurable comparator (4.0 V default) on each input remains
active. The MCU may change or update the tri-state register via software at any time in Normal mode. The tri-state register defaults to 1
(inputs are tri-stated. Any inputs in tri-state is still polled in LPM but the current source is not active during this time. The determination of
change of state occurs at the end of the tACTIVEPOLL and the wake-up decision is made.
Table 16. Tri-state SP register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0000_010 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
11111111
MISO return word bit [23] bit [22] bits [21 - 0]
0000_010[R/W] FAULT
STATUS INTflg Register Data
Table 17. Tri-state SG register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0000_011 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SG13 SG12 SG11 SG10 SG9 SG8
00111111
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7SG6SG5SG4SG3SG2SG1SG0
11111111
MISO return word bit [23] bit [22] bits [21 - 0]
0000_011[R/W] FAULT
STATUS INTflg Register Data
NXP Semiconductors 36
33978
7.10.5 Wetting current level SP register
The IC contains configurable wetting currents (Default = 16 mA). Three bits are used to control each individual input pin with the values
set in Table 18. The MCU may change or update the wetting current register via software at any time in Normal mode.
See Table 21 for the selectable Wetting Current level values for both SPx and SGx pins.
7.10.6 Wetting current level SG register 0
The IC contains configurable wetting currents (Default = 16 mA). Three bits are used to control each individual input pin with the values
set in Table 19. The MCU may change or update the wetting current register via software at any time in Normal mode.
See Table 21 for the selectable Wetting Current level values for both SPx and SGx pins.
Table 18. Wetting current level SP register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit [23 - 21] bit [20 - 18] bit [17 - 16]
0000_100 0/1 SP7 [2-0] SP6[2-0] SP5[2-1]
Default on POR
110 110 11
bit [15] bit [14 - 12] bit [11 - 9] bit [8]
SP5[0] SP4 [2-0] SP3[2-0] SP2[2]
0 110 110 1
bit [7 - 6] bit [5 - 3] bit [2 - 0]
SP2[1-0] SP1[2-0] SP0[2-0]
10 110 110
MISO return word bits [23 - 0]
0000_100[R/W] Register Data
Table 19. Wetting current level SG register 0
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit [23 - 21] bit [20 - 18] bit [17 - 16]
0000_101 0/1 SG7 [2-0] SG6[2-0] SG5[2-1]
Default on POR
110 110 11
bit [15] bit [14 - 12] bit [11 - 9] bit [8]
SG5[0] SG4 [2-0] SG3[2-0] SG2[2]
0 110 110 1
bit [7 - 6] bit [5 - 3] bit [2 - 0]
SG2[1-0] SG1[2-0] SG0[2-0]
10 110 110
MISO return word bits [23 - 0]
0000_101[R/W] Register Data
37 NXP Semiconductors
33978
7.10.7 Wetting current level SG register 1
The IC contains configurable wetting currents (Default = 16 mA). Three bits are used to control each individual input pin with the values
set in Table 20. The MCU may change or update the wetting current register via software at any time in Normal mode.
See Table 21 for the selectable Wetting Current level values for both SPx and SGx pins.
Table 20. Wetting current level SG register 1
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit [23 - 21] bit [20 - 18] bit [17 - 16]
0000_110 0/1 Unused SG13[2-1]
Default on POR
011
bit [15] bit [14 - 12] bit [11 - 9] bit [8]
SG13[0] SG12 [2-0] SG11[2-0] SG10[2]
0 110 110 1
bit [7 - 6] bit [5 - 3] bit [2 - 0]
SG10[1-0] SG9[2-0] SG8[2-0]
10 110 110
MISO return word bits [23 - 0]
0000_110[R/W] Register Data
Table 21. SPx/SGx selectable wetting current levels
SPx/SGx[2-0]
Wetting Current Level
bit 2 bit 1 bit 0
0002.0 mA
0016.0 mA
0108.0 mA
0 1 1 10 mA
1 0 0 12 mA
1 0 1 14 mA
1 1 0 16 mA
1 1 1 20 mA
NXP Semiconductors 38
33978
7.10.8 Continuous wetting current SP register
Each switch input has a designated 20 ms timer. The timer starts when the specific switch input crosses the comparator threshold. When
the 20 ms timer expires, the contact current is reduced from the configured wetting current (16 mA) to the Sustain current. The wetting
current is defined to be an elevated level that reduces to the lower sustain current level after the timer has expired. With multiple wetting
current timers disabled, power dissipation for the IC must be considered.
The MCU may change or update the continuos wetting current register via software at any time in Normal mode. This allows the MCU to
control the amount of time wetting current is applied to the switch contact. Programming the continuos wetting current bit to logic [0]
operates normally with a higher wetting current followed by sustain current after 20 ms (pulsed Wetting current operation). Programming
to logic [1] enables the continuous wetting current (Table 22) and results in a full time wetting current level. The continuous wetting current
register defaults to 0 (pulse wetting current operation).
7.10.9 Continuous Wetting Current SG Register
Each switch input has a designated 20 ms timer. The timer starts when the specific switch input crosses the comparator threshold. When
the 20 ms timer expires, the contact current is reduced from the configured wetting current (16 mA) to 2.0 mA. The wetting current is
defined to be at an elevated level that reduces to the lower sustain current level after the timer has expired. With multiple wetting current
timers disabled, power dissipation for the IC must be considered.
The MCU may change or update the continuous wetting current register via software at any time in Normal mode. This allows the MCU
to control the amount of time wetting current is applied to the switch contact. Programming the continuos wetting current bit to logic [0]
operates normally with a higher wetting current followed by sustain current after 20 ms (Pulse wetting current operation). Programming to
logic [1] enables the continuous wetting current (Table 23) and results in a full time wetting current level. The continuous wetting current
register defaults to 0 (pulse wetting current operation).
Table 22. Continuous wetting current SP register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0001_011 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0001_011[R/W] FAULT
STATUS INTflg Register Data
39 NXP Semiconductors
33978
Figure 22. Pulsed/continuous wetting current configuration
Table 23. Continuous wetting current SG register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0001_100 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SG13 SG12 SG11 SG10 SG9 SG8
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7SG6SG5SG4SG3SG2SG1SG0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0001_100[R/W] FAULT
STATUS INTflg Register Data
Switch to
Ground open
Switch to
Ground Closed
IWET
ISUS=~2mA
0 ma
20 ms
IWET
0 ma
Continuous wetting
current enabled
Continuous wetting
current disabled
NXP Semiconductors 40
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7.10.10 Interrupt enable SP register
The interrupt register defines the inputs that are allowed to Interrupt the 33978 Normal mode. Programming the interrupt bit to logic [0]
disables the specific input from generating an interrupt. Programming the interrupt bit to logic [1] enables the specific input to generate an
interrupt with switch change of state The MCU may change or update the interrupt register via software at any time in Normal mode. The
Interrupt register defaults to logic [1] (Interrupt enabled).
7.10.11 Interrupt enable SG register
The interrupt register defines the inputs that are allowed to Interrupt the 33978 Normal mode. Programming the interrupt bit to logic [0]
disables the specific input from generating an interrupt. Programming the interrupt bit to logic [1] enables the specific input to generate an
interrupt with switch change of state The MCU may change or update the interrupt register via software at any time in Normal mode. The
Interrupt register defaults to logic [1] (Interrupt enabled).
Table 24. Interrupt enable SP register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0001_101 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
11111111
MISO return word bit [23] bit [22] bits [21 - 0]
0001_101[R/W] FAULT
STATUS INTflg Register Data
Table 25. Interrupt enable SG register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0001_110 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SG13 SG12 SG11 SG10 SG9 SG8
00111111
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7 SG6 SG5 SG4 SG3 SG2 SG1 SG0
11111111
MISO return word bit [23] bit [22] bits [21 - 0]
0001_110[R/W] FAULT
STATUS INTflg Register Data
41 NXP Semiconductors
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7.10.12 Low-power mode configuration
The device has various configuration settings for the Low-power mode operation. The configuration settings are as follows:
int[3-0] is used to set the interrupt timer value. With the interrupt timer set, the IC wakes up after the selected timer expires and issue an
interrupt. This register can be selected to be OFF such that the IC does not wake-up from an interrupt timer.
poll[3-0] is used to set the normal polling rate for the IC. The polling rate is the time between polling events. The current sources become
active at this time for a time of tACTIVESGPOLLING or tACTIVESBPOLLING for SG or SB channels respectively.
Table 26. Low-power mode configuration register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0001_111 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
int3 int2 int1 int0 poll3 poll2 poll1 poll0
00001111
MISO return word bit [23] bit [22] bits [21 - 0]
0001_111[R/W] FAULT
STATUS INTflg Register Data
Table 27. Low-power mode configuration bits definition
Bit Functions Default value Description
23 - 8 Unused 0 Unused
7 - 4 int[3-0] 0000
Set the Interrupt timer value
• 0000 - OFF
• 0001 - 6.0 ms
• 0010 - 12 ms
• 0011 - 24 ms
• 0100 - 48 ms
• 0101 - 96 ms
• 0110 - 192 ms
• 0111 - 394 ms
• 1000 - 4.0 ms
• 1001 - 8.0 ms
• 1010 - 16 ms
• 1011 - 32 ms
• 1100 - 64 ms
• 1101 - 128 ms
• 1110 - 256 ms
• 1111 - 512 ms
3 - 0 poll[3-0] 1111
Set the polling rate for switch detection
• 0000 - 3.0 ms
• 0001 - 6.0 ms
• 0010 - 12 ms
• 0011 - 24 ms
• 0100 - 48 ms
• 0101 - 68 ms
• 0110 - 76 ms
• 0111 - 128 ms
• 1000 - 32 ms
• 1001 - 36 ms
• 1010 - 40 ms
• 1011 - 44 ms
• 1100 - 52 ms
• 1101 - 56 ms
• 1110 - 60 ms
• 1111 - 64 ms (default)
NXP Semiconductors 42
33978
7.10.13 Wake-up enable register SP
The wake-up register defines the inputs that are allowed to wake the 33978 from Low-power mode. Programming the wake-up bit to
logic [0] disables the specific input from waking the IC (Table 28). Programming the wake-up bit to logic [1] enables the specific input to
wake-up with switch change of state The MCU may change or update the wake-up register via software at any time in Normal mode. The
Wake-up register defaults to logic [1] (wake-up enabled). If all channels (SG and SB) have the Wake-up bit disabled, the device disables
the polling timer to reduce the current consumption during Low-power mode.
7.10.14 Wake-up enable register SG
The wake-up register defines the inputs that are allowed to wake the 33978 from Low-power mode. Programming the wake-up bit to
logic [0] disables the specific input from waking the IC (Table 29). Programming the wake-up bit to logic [1] enables the specific input to
wake-up with any switch change of state The MCU may change or update the wake-up register via software at any time in Normal mode.
The Wake-up register defaults to logic [1] (wake-up enabled). If all channels (SG and SB) have the Wake-up bit disabled, the device
disables the polling timer to reduce the current consumption during Low-power mode.
Table 28. Wake-up enable SP register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0010_000 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
11111111
MISO return word bit [23] bit [22] bits [21 - 0]
0010_000[R/W] FAULT
STATUS INTflg Register Data
Table 29. Wake-up enable SG register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0010_001 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SG13 SG12 SG11 SG10 SG9 SG8
00111111
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7 SG6 SG5 SG4 SG3 SG2 SG1 SG0
11111111
MISO return word bit [23] bit [22] bits [21 - 0]
0010_001[R/W] FAULT
STATUS INTflg Register Data
43 NXP Semiconductors
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7.10.15 Comparator only SP
The comparator only register allows the input comparators to be active during LPM with no polling current. In this case, the inputs can
receive a digital signal on the order of the LPM clock cycle and wake-up on a change of state. This register is intended to be used for
signals that are driven by an external chip and drive to 5.0 V.
7.10.16 Comparator only SG
The comparator only register allows the input comparators to be active during LPM with no polling current. In this case, the inputs can
receive a digital signal on the order of the LPM clock cycle and wake-up on a change of state. This register is intended to be used for
signals that are driven by an external chip and drive to 5.0 V.
Table 30. Comparator only SP Register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0010_010 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0010_010[R/W] FAULT
STATUS INTflg Register Data
Table 31. Comparator only SG register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0010_011 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SG13 SG12 SG11 SG10 SG9 SG8
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7 SG6 SG5 SG4 SG3 SG2 SG1 SG0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0010_011[R/W] FAULT
STATUS INTflg Register Data
NXP Semiconductors 44
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7.10.17 LPM voltage threshold SP configuration
The 33978 is able to use different voltage thresholds to wake-up from LPM. When configured as SG, a Logic [0] means the input will use
the LPM delta voltage threshold to determine the state of the switch. A Logic [1] means the input uses the Normal threshold (VICTHR) to
determine the state of the switch. When configured as an SB, it only uses the 4.0 V threshold regardless the status of the LPM voltage
threshold bit. The user must ensure that the correct current level is set to allow the crossing of the normal mode threshold (typ. 4.0 V)
7.10.18 LPM voltage threshold SG configuration
This means the input uses the LPM delta voltage threshold to determine the state of the switch. A Logic [1] means the input uses the
Normal threshold to determine the state of the switch. The user must ensure that the correct current level is set to allow the crossing of
the normal mode threshold (typ. 4.0 V)
Table 32. LPM voltage threshold configuration SP register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0010_100 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0010_100[R/W] FAULT
STATUS INTflg Register Data
Table 33. LPM voltage threshold configuration SG register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0010_101 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SG13 SG12 SG11 SG10 SG9 SG8
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7 SG6 SG5 SG4 SG3 SG2 SG1 SG0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0010_101[R/W] FAULT
STATUS INTflg Register Data
45 NXP Semiconductors
33978
7.10.19 Polling current SP configuration
The normal polling current for LPM is 2.2 mA for SB channels and 1.0 mA for SG channels, A logic [0] selects the normal polling current
for each individual channel. The user may choose to select the IWET current value as defined in the wetting current level registers by writing
a Logic [1] on this bit; this will result in higher LPM currents but may be used in cases when a higher polling current is needed.
7.10.20 Polling current SG configuration
A Logic [0] selects the normal polling current for LPM =1.0 mA. The user may choose to select the IWET current value as defined in the
wetting current registers for LPM by writing a Logic [1] in this bit; this results in higher LPM currents but may be used in cases when a
higher polling current is needed.
Table 34. Polling current configuration SP register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0010_110 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0010_110[R/W] FAULT
STATUS INTflg Register Data
Table 35. Polling current configuration SG register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0010_111 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SG13 SG12 SG11 SG10 SG9 SG8
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7 SG6 SG5 SG4 SG3 SG2 SG1 SG0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0010_111[R/W] FAULT
STATUS INTflg Register Data
NXP Semiconductors 46
33978
7.10.21 Slow polling SP
The normal polling rate is defined in the Low-power mode configuration register. If the user is able to poll at a slower rate (4x) the LPM
current level decreases significantly. Setting the bit to [0] results in the input polling at the normal rate as selected. Setting the bit to [1]
results in the input being polled at a slower frequency at 4x the normal rate.
7.10.22 Slow polling SG
The normal polling rate is defined in the Low-power mode configuration register. If the user is able to poll at a slower rate (4x) the LPM
current level decreases significantly. Setting the bit to [0] results in the input polling at the normal rate as selected. Setting the bit to [1]
results in the input being polled at a slower frequency at 4x the normal rate.
Table 36. Slow polling SP Register
Register Address R/W SPI Data Bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0011_000 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
00000000
MISO Return Word bit [23] bit [22] bits [21 - 0]
0011_000[R/W] FAULT
STATUS INTflg Register Data
Table 37. Slow Polling SG Register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0011_001 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SG13 SG12 SG11 SG10 SG9 SG8
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7 SG6 SG5 SG4 SG3 SG2 SG1 SG0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0011_001[R/W] FAULT
STATUS INTflg Register Data
47 NXP Semiconductors
33978
7.10.23 Wake-up debounce SP
The IC is able to extend the time that the active polling takes place to ensure that a true change of state has occurred in LPM and reduce
the chance that noise has impacted the measurement. If this bit is [0], the IC uses a voltage difference technique to determine if a switch
has changed sate. If this bit is set [1], the IC debounces the measurement by continuing to source the LPM polling current for an additional
1.2 ms and take the measurement based on the final voltage level. This helps to ensure that the switch is detected correctly in noisy
systems.
7.10.24 Wake-up debounce SG
The IC is able to extend the time that the active polling takes place to ensure that a true change of state has occurred in LPM and reduce
the chance that noise has impacted the measurement. If this bit is [0], the IC uses a voltage difference technique to determine if a switch
has changed sate. If this bit is set [1], the IC debounces the measurement by continuing to source the LPM polling current for an additional
1.2 ms and take the measurement based on the final voltage level. This helps to ensure that the switch is detected correctly in noisy
systems.
Table 38. Wake-up debounce SP register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0011_010 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0011_010[R/W] FAULT
STATUS INTflg Register Data
Table 39. Slow polling SG Register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0011_011 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SG13 SG12 SG11 SG10 SG9 SG8
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7SG6SG5SG4SG3SG2SG1SG0
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0011_011[R/W] FAULT
STATUS INTflg Register Data
NXP Semiconductors 48
33978
7.10.25 Enter low-power mode
Low-power mode (LPM) is used to reduce system quiescent currents. Low-power mode may be entered only by sending the Low-power
command. When returning to Normal mode, all register settings is maintained.
The Enter Low-power mode register is write only and has the effect of going to LPM and beginning operation as selected (polling, interrupt
timer). When returning form Low-power mode, the first SPI transaction will return the Fault Status and the intflg bit set to high, as well as
the actual status of the Input pins.
7.10.26 AMUX control register
The analog voltage on switch inputs may be read by the MCU using the analog command (Table 41). Internal to the33978 is a 24-to-1
analog multiplexer. The voltage present on the selected input pin is buffered and made available on the AMUX output pin. The AMUX
output pin is clamped to a maximum of VDDQ volts regardless of the higher voltages present on the input pin. After an input has been
selected as the analog, the corresponding bit in the next MISO data stream is logic [0].
Setting the current to wetting current (configurable) may be useful for reading sensor inputs. The MCU may change or update the analog
select register via software at any time in Normal mode. The analog select defaults to no input.
Table 40. Enter low-power mode command
Register address W SPI data bits [23 - 0]
[31-25] [24] bits [23 - 16]
0011_100 1 0000_0000
bits [15 - 8]
0000_0000
bits [7 - 0]
0000_0000
MISO return word -
Table 41. Slow polling SG register
Register address R/W SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0011_101 0/1 Unused
Default on POR
00000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused
00000000
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
Unused asett0 asel[5-0]
00000000
MISO return word bit [23] bit [22] bits [21 - 0]
0011_101[R/W] FAULT
STATUS INTflg Register Data
Table 42. AMUX current select
asett[0] Zsource
0 hi Z (default)
1I
WET
49 NXP Semiconductors
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7.10.27 Read switch status
The Read switch status register is used to determine the state of each of the inputs and is read only. All of the inputs (SGn and SPn) are
returned after the next command is sent. A Logic [1] means the switch is closed while a Logic [0] is an open switch.
Included in the status register are two more bits, the Fault Status bit and intflg bit. The Fault Status bit is a combination of the extended
status bits and the wetting current fault bits. If any of these bits are set, the Fault Status bit is set. The intflg bit is set when an interrupt
occurs on this device.
After POR, both the Fault Status bit and the intflg bit are set high to indicate an interrupt due to a POR occurred. The intflg bit will be
cleared upon reading the Read Switch Status register, and the Fault Status bit will remain high until the Fault status register is read and
thus the POR fault bit and all other fault flags are cleared.
The Fault Status and Intflg bits are semi-global flags, if a fault or an interrupt occurs, these bit will be returned after writing or reading any
command, except for the SPICheck and the Wetting Current configuration registers, which use those bits to set/display the device
configuration.
Table 43. AMUX channel select
asel 5 asel 4 asel3 asel 2 asel 1 asel 0 Analog channel select
0 0 0 0 0 0 No Input Selected
000001 SG0
000010 SG1
000011 SG2
000100 SG3
000101 SG4
000110SG5
000111SG6
001000SG7
001001SG8
001010SG9
001011SG10
001100SG11
001101SG12
001110SG13
001111SP0
010000SP1
010001SP2
010010SP3
010011SP4
010100SP5
010101SP6
010110SP7
0 1 0 1 1 1 Temp Diode
011000Battery Sense
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The fault/status diagnostic capability consists of one internal 24 bit register. The content of the fault/status register is shown in Table 45.
Bits 0 – 21 shows the status of each input where logic [1] is a closed switch and logic [0] is an open switch. In addition to input status
information, Fault status such as die over-temp, Hash fault, SPI errors, as well as interrupts are reported.
A SPI read cycle is initiated by a CS_B logic ‘1’ to ‘0’ transition, followed by 32 SCLK cycles to shift the fault / status registers out the MISO
pin. The INT_B pin is cleared 1.0 ms after the falling edge of CS_B. The fault is immediately set again if the fault condition is still present.
The Fault Status bit sets any time a Fault occurs, and the Fault register (Table 46) must be read in order to clear the Fault status flag.
The intflg bit sets any time an interrupt event occurs (change of state on switch, any fault status bit gets set). Any SPI message that will
return intflg bit will clear this flag (even if the event is still occurring, for example an overtemp, will cause an interrupt. The interrupt can be
cleared but the chip will not interrupt again based on the overtemp until that fault has gone away).
Bit 23 : Fault Status:
• 0 = No Fault
• 1 = Indicates a fault has occurred and should be viewed in the fault status register.
Bit 22 : Intflg:
• 0 = No Change of state
• 1 = Change of state detected.
Bit 21 – 0 : SPx /SGx input status:
• 0 = Open switch;
• 1 =Closed switch
Table 44. Read switch status command
Register address R SPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0011_111 0 FAULT
STATUS INTflg SP7 SP6 SP5 SP4 SP3 SP2
Default After POR
11XXXXXX
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
SP1 SP0 SG13 SG12 SG11 SG10 SG9 SG8
XXXXXXXX
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SG7SG6SG5SG4SG3SG2SG1SG0
XXXXXXXX
MISO return word bit [23] bit [22] bits [21-14] bits [13-0]
0011_1110 FAULT
STATUS INTflg SP7 -SP0 Switch Status SG13 - SG0 Switch Status
Table 45. MISO output register definition
MISO
Response
Sends
Fault Status
INTflg
SP7
SP6
SP5
SP4
SP3
SP2
SP1
SP0
SG13
SG12
SG11
SG10
SG9
SG8
SG7
SG6
SG5
SG4
SG3
SG2
SG1
SG0
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7.10.28 Fault status register
To read the fault status bits the user should first sent a message to the IC with the fault status register address followed by any given
second command. The MISO response from the second command will contain the fault flags information.
Table 46. Fault status register
Register address RSPI data bits [23 - 0]
[31-25] [24] bit 23 bit 22 bit 21 bit 20 bit 19 bit 18 bit 17 bit 16
0100_001 0 Unused INTflg Unused
Default After POR
01000000
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8
Unused SPI error Hash Fault Unused
00000XX0
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
UV OV TempFlag OT INT_B Wake WAKE_B
Wake SPI Wake POR
XXXXXXXX
MISO return word bit [23] bit [22] bits [21-0]
0100_0010 FAULT
STATUS INTflg FAULT/FLAG BITS
Table 47. MISO response for fault status command
Bit Functions Default value Description
23 Unused 0 Unused
22 INTflg X
Reports that an Interrupt has occurred, user should read the status register to determine cause.
• Set: Various (SGx change of state, SPx change of state, Extended status bits).
• Reset: Clear of fault or read of Status register
21-11 Unused 0 Unused
10 SPI error X
Any SPI error generates a bit (Wrong address, incorrect modulo).
• Set: SPI message error.
• Reset: Read fault status register and no SPI errors.
9 Hash Fault X
SPI register and hash mismatch.
• Set: Mismatch between SPI registers and hash.
• Reset: No mismatch and SPI flag read.
8 Unused 0 Unused
7UV X
Reports that low VBATP voltage was in undervoltage range
• Set: Voltage drops below UV level.
• Reset: VBATP rises above UV level and flag read (SPI)
6OV X
Report that the voltage on VBATP was higher than OV threshold
• Set: Voltage at VBATP rises above overvoltage threshold.
• Reset: Overvoltage condition is over and flag read (SPI)
5 Temp Flag X
Temperature warning to note elevated IC temperature
• Set: tLIM warning threshold is passed.
• Reset: Temperature drops below thermal warning threshold + hysteresis and flag read (SPI)
4OT X
Tlim event occurred on the IC
• Set: Tlim warning threshold is passed.
• Reset: Temperature drops below thermal warning threshold + hysteresis and flag read (SPI)
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7.10.29 Interrupt request
The MCU may request an Interrupt pulse of duration 100 μs by sending the Interrupt request command. After an Interrupt request
commands, the 33978 returns the Interrupt request command word, as well as the Fault status and INTflg bits set if a fault/interrupt event
occurred. Sending an interrupt request command does not set the INTflg bit itself.
7.10.30 Reset register
Writing to this register causes all of the SPI registers to reset.
3 INT_B Wake X
Part awakens via an external INT_B falling edge
• Set: INT_B Wakes the part from LPM (external falling edge)
• Reset: flag read (SPI).
2 WAKE_B Wake X
Part awakens via an external WAKE_B falling edge
• Set: External WAKE_B falling edge seen
• Reset: flag read (SPI).
1 SPI Wake X
Part awaken via a SPI message
• Set: SPI message wakes the IC from LPM
• Reset: flag read (SPI).
0POR X
Reports a POR event occurred.
• Set: Voltage at VBATP pin dropped below VBATP(POR) voltage
• Reset: flag read (SPI)
Table 48. Interrupt request command
Register address W SPI data bits [23 - 0]
[31-25] [24] bits [23 - 16]
0100_011 1 0000_0000
bits [15 - 8]
0000_0000
bits [7 - 0]
0000_0000
MISO return word bit [23] bit [22] bits [21-0]
0100_0111 FAULT
STATUS INTflg 0
Table 49. Reset command
Register address WSPI data bits [23 - 0]
[31-25] [24] bits [23 - 16]
0100_100 1 0000_0000
bits [15 - 8]
0000_0000
bits [7 - 0]
0000_0000
MISO return word bit [23] bit [22] bits [21-0]
0011_1110 FAULT
STATUS INTflg Switch Status
Table 47. MISO response for fault status command (continued)
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8 Typical applications
8.1 Application diagram
Figure 23. Typical application diagram
8.2 Bill of materials
Table 50. Bill of materials
Item Quantity Reference Value Description
124
C1, C2, C3, C4, C5, C6, C7, C8, C9, C10,
C11, C12, C13, C14, C15, C16, C17, C18,
C19, C20, C21, C22, C25, C27
0.1 μF CAP CER 0.1 uF 100 V X7R 10 % 0603
2 2 C23,C24 1.0 nF CAP CER 1000 PF 100 V 10 % X7R 0603
31C26 100
μF CAP ALEL 100 μF 50 V 20 % -- SMD
4 1 D1 - DIODE RECT 3.0 A 50 V AEC-Q101 SMB
522
R1, R2, R3, R4, R5, R6, R7, R8, R9, R10,
R11, R12, R13, R14, R15, R16, R17, R18,
R19, R20, R21, R22
100 ΩRES MF 100 Ω 0.5 W 1% 0805
6 1 R23 10 kΩRES MF 10 kΩ 0.5 W 5 % 0805 (optional)
7 1 R25 10 kΩRES MF 10 kΩ 0.5 W 5 % 0805
8 1 R24 1.0 kΩRES MF 1 kΩ 0.5 W 5 % 0805
9 1 U1 MC33978 IC MULTIPLE DETECTION SWITCH INTERFACE SOIC32
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8.3 Abnormal operation
The 33978 could be subject to various conditions considered abnormal as defined within this section.
8.3.1 Reverse battery
This device with applicable external components will not be damaged by exposure to reverse battery conditions of -14 V. This test is
performed for a period of one minute at 25 °C. In addition, this negative voltage condition does not force any of the logic level I/O pins to
a negative voltage less than -0.6 V at 10 mA or to a positive voltage greater the 5.0 V. This insures protection of the digital device
interfacing with this device.
8.3.2 Ground offset
The applicable driver outputs and/or current sense inputs are capable of operation with a ground offset of ±1.0 V. The device will not be
damaged by exposure to this condition and will maintain specified functionality.
8.3.3 Shorts to ground
All I/Os of the device that are available at the module connector are protected against shorts to ground with maximum ground offset
considered (i.e. -1.0 V referenced to device ground or other application specific value). The device will not be damaged by this condition.
8.3.4 Shorts to battery
All I/Os of the device that are available at the module connector are protected against a short to battery (voltage value is application
dependent, there may be cases where short to jump start or load dump voltage values are required). The device will not be damaged by
this condition.
8.3.5 Unpowered shorts to battery
All I/Os of the device that are available at the module connector are protected against unpowered (battery to the module is open) shorts
to battery per application specifics. The device will not be damaged by this condition, will not enable any outputs nor backfeed onto the
power rails (VBATP, VDDQ) or the digital I/O pins.
8.3.6 Loss of module ground
The definition of a loss of ground condition at the device level is that all pins of the IC detects very low-impedance to battery. The
nomenclature is suited to a test environment. In the application, a loss of ground condition results in all I/O pins floating to battery voltage,
while all externally referenced I/O pins are at worst case pulled to ground. All applicable driver outputs and current sense inputs are
protected against excessive leakage current due to loads that are referenced to an external ground (high-side drivers).
8.3.7 Loss of module battery
The loss of battery condition at the parts level is that the power input pins of the IC see infinite impedance to the battery supply voltage
(depending upon the application) but there is some undefined impedance looking from these pins to ground. All applicable driver outputs
and current sense inputs are protected against excessive leakage current due to loads that are referenced to an external battery
connection (low-side drivers).
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9 Packaging
9.1 Package mechanical dimensions
Package dimensions are provided in package drawings. To find the most current package outline drawing, go to www.nxp.com and
perform a keyword search for the drawing’s document number.
Table 51. Packaging information
Package Suffix Package outline drawing number
32-Pin SOICW-EP EK 98ASA10556D
32-Pin QFN (WF-type) ES 98ASA00656D
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10 Reference section
Table 52. 33978 reference documents
Reference Description
CDF-AEC-Q100 Stress Test Qualification For Automotive Grade Integrated Circuits
Q-1000 Qualification Specification for Integrated Circuits
SQ-1001 Specification Conformance
ISO 7637 Electrical Disturbances from Conduction and Coupling
ISO 61000 Electromagnetic Compatibility
63 NXP Semiconductors
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11 Revision history
Revision Date Description of changes
1.0 3/2014 • Initial release
2.0 3/2014 • Removed Z from part numbers PCZ33978EK and PCZ33978ES in the Orderable part variations table
3.0 12/2014
• Major formatting and information arrangement
• Updated Figure 1, 33978 simplified application diagram, removed CS_B pull-up resistor, not needed.
• Added Industrial Part numbers MC34978EK and MC34978ES to Table 1
•Table 3 Clarified Switch Input Range specification (not a differential voltage between inputs and VBATP)
•Table 3 Reduced Human Body Model (HBM) (VBATP versus GND) to 2500 V
•Table 3 VESD6-2 Series resistor corrected to 50 Ω, Added missing CZAP and RZAP conditions
•Table 4 Updated Thermal Resistance specification
• Added Figure 10, Functional block diagram
• Added Figure 11, Battery voltage range
• Added Figure 5, Glitch filter and interrupt delay timers and Figure 6, Interrupt pulse timer
• Updated POR minimum specification to 2.7 V (previous 2.9 V)
• Updated VBATP Normal mode maximum supply current to 12 mA (previous 8.0 mA)
• Updated VDDQ undervoltage threshold maximum to 2.8 V (previous 2.7 V)
• Updated sustain current at low battery to 2.4 mA (previous 2.0 mA)
• Added a specification to cover the Normal mode switch detection threshold hysteresis.
• Updated minimum limit on Switch detection threshold in LPM to 80 mV
• Updated minimum ratio for switch threshold at low battery to 0.55x (previous 0.8x)
• Fixed typo on Input threshold specifications to VDD*0.25 and VDD*0.7
• Updated the INT_B VOL maximum level to 0.5 V (previous 0.4 V)
• Updated limits on the POR to Active time to 250 μs (min) to 450 μs (max) (previous min was 40 μs)
• Clarified Operating voltage range (4.5 V to 28 V)
• Corrected WAKE_B Max rating to 40 V.
• Added Figure 19, SPI write operation and Figure 20, SPI read operation
• Added Table 7.10.1, SPI check
• Corrected Rb/W bits on Table 11 From 1/0 to 0/1
• Clarified SPI Read/write operation and SPI registers information.
• Updated VBATP(POR) maximum voltage to 3.8 V.
• Updated VBATP under voltage hysteresis minimum voltage to 250 mV
• Updated VBATP low-power mode supply current to 40 uA
• Input logic voltage threshold WAKE_B typical value added at 1.25 V, max value updated to 1.7 V
• Added new Specification for WAKE_B input logic hysteresis.
• Clarified AMUX accuracy and Coefficient accuracy specifications, added Figure 4, Divide by 6 coefficient accuracy.
• Update internal pull-up resistance to 270 KΩ (INT_B, WAKE_B, CS_B)
• Low-power mode oscillator frequency centered at 192 KHz with +/- 15% tolerance.
• Updated all timing specs derived from the 192 kHz oscillator (Low-power mode)
• Added SBPOLLTIME (bit 13) selection functionality on 7.10.2, “Device configuration register"
• Added SB Tactive Polling time specification (58 μs or 1.2 ms Typical)
•Table 6 Clarified wetting current specification for SB and SG channels.
• SB sustain Current and Low-power mode polling current SB Typical value centered at 2.2mA, Min = 1.75 mA and Max
= 2.65 mA, (+/- 20% tolerance).
• Wetting current matching, Max value updated to 6%
• Updated Switch detection Threshold in Low Voltage maximum value to 4.3 V.
• Added Figure 22, Pulsed/continuous wetting current configuration
• Removed section (Electrical Test requirement, Stress testing, and EMC consideration)
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4.0 12/2014
• Changed VESD1-2 to ±2000
• Changed ISUSSB max. value to 2.85 mA
• Changed IACTIVEPOLLSB max. value to 2.85 mA
• Changed PC33978EK and PC34978EK parts to MC in the Orderable part variations table
5.0
8/2015
• Deleted PC33978ES and PC34978ES part numbers
• Updated case outline
• Added new part numbers MC33978AEK, MC33978AES, MC34978AEK, and MC34978AES to the Orderable part vari-
ations table
• Updated AMUX specification for QFN package
• Added thermal characteristics for QFN package
• Updated VBATP HBM specification to 4.0 KV
8/2015 • Added additional line to VESD1-2 spec in Table 3 to show the max. value for MC33978/MC34978 and MC33978A/
MC34978A
8/2016 • Updated to NXP document form and style
6.0 2/2017 • Added note (4) to switch input voltage range in Table 3
7.0 8/2017
• Added a new parameter tCSB_WAKEUP to Table 7
• Updated the dynamic electrical characteristics condition statement in Table 7 (changed “VBATP = 4.5 V to 28 V” to
“VBATP = 6.0 V to 28 V”)
8.0 7/2018 • Changed document status from Advance Information to Technical Data
Revision Date Description of changes
Information in this document is provided solely to enable system and software implementers to use NXP products.
There are no expressed or implied copyright licenses granted hereunder to design or fabricate any integrated circuits
based on the information in this document. NXP reserves the right to make changes without further notice to
anyproducts herein.
NXP makes no warranty, representation, or guarantee regarding the suitability of its products for any particular
purpose, nor does NXP assume any liability arising out of the application or use of any product or circuit, and
specifically disclaims any and all liability, including without limitation, consequential or incidental damages. "Typical"
parameters that may be provided in NXP data sheets and/or specifications can and do vary in different applications,
and actual performance may vary over time. All operating parameters, including "typicals," must be validated for each
customer application by the customer's technical experts. NXP does not convey any license under its patent rights nor
the rights of others. NXP sells products pursuant to standard terms and conditions of sale, which can be found at the
following address:
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© NXP B.V. 2018.
Document Number: MC33978
Rev. 8.0
7/2018