MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
General Description
The MAX16963 is a high-efficiency, dual synchronous
step-down converter that operates with a 2.7V to 5.5V
input voltage range and provides a 0.8V to 3.6V output
voltage range. The device delivers up to 1.5A of load
current per output. The low input/output voltage range
and the ability to provide high output currents make this
device ideal for on-board point-of-load and postregulation
applications. The device achieves Q3% output error over
load, line, and temperature ranges.
The device features a 2.2MHz fixed-frequency PWM mode
for better noise immunity and load transient response,
and a skip mode for increased efficiency during light-load
operation. The 2.2MHz frequency operation allows for
an all-ceramic capacitor design and small-size external
components. An optional spread-spectrum frequency
modulation minimizes radiated electromagnetic emissions
due to the switching frequency.
On-board low RDSON switches help minimize efficiency
losses at heavy loads and reduce critical/parasitic induc-
tance, making the layout a much simpler task with respect
to discrete solutions. Following a simple layout and footprint
ensures first-pass success in new designs.
The device is offered in a factory-preset output voltage or
adjustable output-voltage version (see the Selector Guide
for options). Factory-preset output-voltage versions allow
customers to achieve Q3% output-voltage accuracy without
using external resistors, while the adjustable output-voltage
version provides the flexibility to set the output voltage to
any desired value between 0.8V and 3.6V using an external
resistive divider.
Additional features include 8ms fixed soft-start, 16ms
fixed power-good delay, overcurrent, and overtemperature
protections.
The MAX16963 is available in thermally enhanced 16-pin
TSSOP-EP and 4mm x 4mm, 16-pin TQFN-EP packages,
and is specified for operation over the -40NC to +125NC
automotive temperature range.
Applications
Automotive Postregulation
Industrial/Military
Point-of-Load Applications
Benefits and Features
S Small Size Components
Dual 2.2MHz DC-DC Converter
S Ideal for Point-of-Load Applications
Up to 1.5A Output Current
Adjustable Output Voltage: 0.8V to 3.6V
2.7V to 5.5V Operating Supply voltage
S High Efficiency at Light Load
Skip Mode with 36µA Quiescent Current
S Low Electromagnetic Emission
Programmable SYNC I/O Pin
Spread Spectrum
S Low Power Mode Saves Energy
Independent Enable Inputs
S Output Rail Monitoring Helps Prevent System Failure
Open-Drain Power-Good Output
S Limits Inrush Current During Startup
Built-In Soft-Start Timer
S Overtemperature and Short-Circuit Protections
S 4mm x 4mm, 16-Pin TQFN and 16-Pin TSSOP
Packages
S -40NC to 125NC Operating Temperature Range
Typical Application Circuit
19-6487; Rev 5; 7/15
Ordering Information appears at end of data sheet.
EVALUATION KIT AVAILABLE
MAX16963
OUTS1PV1
LX1
PGND1
PG1
EP
2.2µH
22µF
20kΩ
10Ω
4.7µF
1µF
VPV1
VOUT1
EN1
GND
PG2
PV
VPV
VOUT2
20kΩ
VOUT1
OUTS2
LX2
PGND2
1.5µH
22µF
VOUT2
PV2
4.7µF
VPV2
EN2
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
2Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
PV, PV1, PV2 to GND ..............................................-0.3V to +6V
EN1, EN2, PG1, PG2 to GND .................................-0.3V to +6V
LX_ Current ........................................................... ±1.6 (Note 1)
PGND1 and PGND2 to GND ..............................-0.3V to +0.3V
PV to PV1 and PV2 ............................................... -0.3V to +0.3V
LX1 and LX2 Continuous RMS Current ...................................1A
All Other Pins Voltages to GND .. (VPV + 0.3V) to (VGND - 0.3V)
Output Short-Circuit Duration .................................... Continuous
Continuous Power Dissipation (TA = +70NC)
TQFN (derate 25mW/NC above +70NC)................... 2000mW*
TSSOP (derate 26.1mW/NC above +70NC)........... 2088.8mW*
Operating Temperature Range ........................ -40NC to +125NC
Junction Temperature .....................................................+150NC
Storage Temperature Range ............................ -65NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
TQFN
Junction-to-Ambient Thermal Resistance (BJA) ..........40NC/W
Junction-to-Case Thermal Resistance (BJC) .................6NC/W
TSSOP
Junction-to-Ambient Thermal Resistance (BJA) .......38.3NC/W
Junction-to-Case Thermal Resistance (BJC) .................3NC/W
ABSOLUTE MAXIMUM RATINGS
Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
PACKAGE THERMAL CHARACTERISTICS (Note 2)
ELECTRICAL CHARACTERISTICS
(VPV = VPV1 = VPV2 = 5V, VEN_ = 5V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
*As per JEDEC51 Standard (multilayer board).
Note 1: LX_ has internal clamp diodes for PGND_ and PV_. Applications that forward bias these diodes should take care not to
exceed the IC’s package power-dissipation limits.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage Range VPV Normal operation 2.7 5.5 V
Supply Current IPV No load, VPWM = 0V 16 36 60 FA
Shutdown Supply Current ISHDN VEN1 = VEN2 = 0V, TA = +25°C 1 5 FA
Undervoltage Lockout Threshold
Low VUVLO_L 2.37 V
Undervoltage Lockout Threshold
High VUVLO_H 2.6 V
Undervoltage Lockout Hysteresis 0.07 V
SYNCHRONOUS STEP-DOWN DC-DC CONVERTER 1
FB Regulation Voltage VOUTS1 800 mV
Feedback Set-Point Accuracy VOUTS1
ILOAD = 4% to 100% -3 0 +3 %
ILOAD = 0% -0.5 +2 +3 %
pMOS On-Resistance RDSON_P1 VPV1 = 5V, ILX1 = 0.4A 90 148 mI
nMOS On-Resistance RDSON_N1 VPV1 = 5V, ILX1 = 0.8A 68 128 mI
Maximum pMOS Current-Limit
Threshold ILIMP1 1.95 2.35 3.15 A
3Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(VPV = VPV1 = VPV2 = 5V, VEN_ = 5V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Maximum Output Current IOUT1 (VOUT1 + 0.5V P VPV1 P 5.5V) (Note 4) 1.5 A
OUTS1 Bias Current IB_OUTS1
Fixed output-voltage variants -1 +1 FA
Adjustable output variants -1 +1
LX1 Leakage Current ILX1_LEAK VPV1 = 6V, LX1 =
PGND1 or PV1
TA = +25°C -1 +1 FA
TA = +125°C -5 +5
Minimum On-Time tON_MIN 60 ns
LX1 Discharge Resistance RLX1 VEN1 = 0V, through the OUTS_ pin 15 24 55 I
Maximum Short-Circuit Current 3.9 A
SYNCHRONOUS STEP-DOWN DC-DC CONVERTER 2
FB Regulation Voltage VOUTS2 800 mV
Feedback Set-Point Accuracy VOUTS2
ILOAD = 4% to 100% -3 0 +3 %
ILOAD = 0% +1 +2 +3
pMOS On-Resistance RDSON_P2 VPV2 = 5V, ILX2 = 0.4A 90 148 mI
nMOS On-Resistance RDSON_N2 VPV2 = 5V, ILX2 = 0.8A 68 128 mI
Maximum pMOS Current-Limit
Threshold ILIMP2 1.95 2.55 3.15 A
Maximum Output Current IOUT2 (VOUT2 + 0.5V P VIN2 P 5.5V) (Note 4) 1.5 A
OUTS2 Bias Current IB_OUTS2
Fixed output-voltage variants 1 2 5 FA
Adjustable output variants 1
LX2 Leakage Current ILX2_LEAK VPV2 = 6V, LX2 =
PGND2 or PV2
TA = +25°C -1 +1 FA
TA = +125°C -5 +5
Minimum On-Time tON_MIN 60 ns
LX2 Discharge Resistance RLX2 VEN2 = 0V, through the OUTS_ pin 15 24 55 I
Maximum Short-Circuit Current 3.9 A
OSCILLATOR
Oscillator Frequency fSW 2.0 2.2 2.4 MHz
Spread Spectrum Df/f Spread spectrum enabled +6 %
SYNC Input Frequency Range fSYNC 50% duty cycle (Note 5) 1.7 2.4 MHz
THERMAL OVERLOAD
Thermal Shutdown Threshold 165 °C
Thermal Shutdown Hysteresis 15 °C
POWER-GOOD OUTPUTS (PG1, PG2)
PG_ Overvoltage Threshold PGOVTH Percentage of nominal output 106 110 114 %
PG_ Undervoltage Threshold PGUVTH Percentage of nominal output 89.5 92 94 %
Active Timeout Period 16 ms
4Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(VPV = VPV1 = VPV2 = 5V, VEN_ = 5V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
Note 3: All limits are 100% production tested at +25°C. Limits over temperature are guaranteed by design.
Note 4: Calculated value based on an assumed inductor ripple of 30%.
Note 5: For SYNC frequency outside (1.7, 2.4)MHz, contact the factory.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Undervoltage/Overvoltage
Propagation Delay 28 Fs
Output High Leakage Current TA = +25°C 0.2 FA
PG1 Output Low Voltage 2.6V ≤ VPV1 ≤ 5.5V, ISINK = 3mA 0.4 V
VPV1 = 1.2V, ISINK = 100FA 0.4
PG2 Output Low Voltage 2.6V ≤ VPV2 ≤ 5.5V, ISINK = 3mA 0.4 V
VPV2 = 1.2V, ISINK = 100FA 0.4
ENABLE INPUTS (EN1, EN2)
Input Voltage High VINH Input rising 2.4 1.7 2.4 V
Input Voltage Low VINL Input falling 0.5 0.85 0.5 V
Input Hysteresis 0.85 V
Input Current VEN_ = high 0.1 1.0 2 FA
Pulldown Resistor VEN_ = low 50 100 200 kI
DIGITAL INPUTS (SYNC, PWM)
Input Voltage High VINH 1.8 V
Input Voltage Low VINL 0.4 V
Input Voltage Hysteresis 50 mV
Pulldown Resistor 50 100 200 kI
DIGITAL OUTPUT (SYNC)
SYNC Output Voltage Low VOL ISINK = 3mA 0.4 V
SYNC Output Voltage High VOH VPV_ = 5V, ISOURCE = 3mA 4.2 V
5Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
Typical Operating Characteristics
(VPV = VPV1 = 5V, VEN1 = VEN2 = 5V, VOUT1 = 3.3V, VOUT2 = 1.8V, TA = +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
(VOUT = 3.3V)
MAX16963 toc01
LOAD CURRENT (A)
EFFICIENCY (%)
10.10.01
10
20
30
40
50
60
70
80
90
100
0
0.001 10
VIN = 5V
PWM
SKIP
EFFICIENCY vs. LOAD CURRENT
(VOUT = 1.8V)
MAX16963 toc02
LOAD CURRENT (A)
EFFICIENCY (%)
10.10.01
10
20
30
40
50
60
70
80
90
100
0
0.001 10
VIN = 5V
PWM
SKIP
VOUT LOAD REGULATION (PWM)
MAX16963 toc03
ILOAD (A)
REGULATION (%)
1.251.000.750.500.25
-2.5
-2.0
-1.5
-1.0
-0.5
0
-3.0
0 1.50
VIN = 5V
VOUT = 3.3V
TA = -40°C
TA = +25°C
TA = +125°C
VOUT1 LOAD REGULATION (SKIP)
MAX16963 toc04
ILOAD (A)
REGULATION (%)
1.251.000.750.500.25
-2.5
-2.0
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
-3.0
0 1.50
VIN = 5V
VOUT = 3.3V
TA = -40°C
TA = +25°C
TA = +125°C
IPV vs. TEMPERATURE (SKIP)
MAX16963 toc07
TEMPERATURE (°C)
IPV (µA)
1109580655035205-10-25
25
30
35
40
45
50
20
-40 125
VPV = 5V
VPWM = 0V
VEN1 = VEN2 = VPV
VOUT1 = VOUT2 = 0.8
VOUT LINE REGULATION (PWM)
MAX16963 toc05
VPV (V)
REGULATION (%)
5.14.73.1 3.5 3.9 4.3
-0.35
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0
-0.40
2.7 5.5
VOUT = 1.8V
ILOAD = 0.75A
TA = +125°C
TA = -40°C
TA = +25°C
LOAD-TRANSIENT RESPONSE (PWM)
MAX16963 toc08
1.5A
0.15A
0A
50mv/div
VOUT
AC-COUPLED
ILOAD
100µs/div
VOUT = 3.3V
IPV vs. VPV (SKIP)
MAX16963 toc06
VPV (V)
IPV (µA)
5.04.54.03.53.0
20
30
40
50
60
70
10
2.5 5.5
VPWM = 0V
VEN1 = VEN2 = VPV
VOUT1 = VOUT2 = 0.8V
TA = +125°C
TA = -40°C
TA = +25°C
fSW vs. TEMPERATURE
MAX16963 toc09
TEMPERATURE (°C)
fSW (MHz)
1109565 80-10 5 20 35 50-25
2.02
2.04
2.06
2.08
2.10
2.12
2.14
2.16
2.18
2.20
2.00
-40 125
VIN = 5V
PWM MODE
ILOAD = 0A
6Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
Pin Configurations
Pin Descriptions
PIN NAME FUNCTION
TQFN TSSOP
1 3 LX2 Converter #2 Switching Node. LX2 is high impedance when converter #2 is off.
2 4 PGND2 Converter #2 Power Ground
3 5 PGND1 Converter #1 Power Ground
4 6 LX1 Converter #1 Switching Node. LX1 is high impedance when converter #1 is off.
5 7 PV1 Converter #1 Input Supply. Bypass PV1 with at least a 4.7FF ceramic capacitor to PGND1.
6 8 EN1 Converter #1 Enable Input. Drive EN1 high to enable converter #1. Drive EN1 low to disable
converter #1.
7 9 OUTS1 Converter #1 Feedback Input (Adjustable Output Option Only). Connect an external resistive
divider from VOUT1 to OUTS1 and GND to set the output voltage.
8 10 PG1 OUT1 Power-Good Output. Open-drain output. PG1 asserts when VOUT1 drops by 8%. Connect
to a 10kI pullup resistor.
9 11 GND Ground
10 12 PWM PWM Control Input. Drive PWM high to put converters in forced PWM mode. Drive PWM low to
put converters in skip mode.
11 13 SYNC Factory-Set Sync Input or Output. As an input, SYNC accepts a 1.7MHz to 2.5HMz external
signal. As an output, SYNC outputs a 90° phase-shifted signal with respect to internal oscillator.
15
16
14
13
6
5
7
PGND2
LX1
8
LX2
SYNC
GND
PV
12
OUTS2
4
12 11 9
EN2
PV2
PG1
OUTS1
EN1
PV1
+
PGND1 PWM
3
10
PG2
TQFN-EP
(4mm x 4mm)
TOP VIEW
+
TSSOP-EP
134 SYNC
PGND2
143 PV
LX2
152 PG2
PV2
161 OUTS2EN2
107 PG1
PV1
116 GND
LX1
98 OUTS1
EN1
125 PWM
PGND1
EP
EP
TOP VIEW
MAX16963 MAX16963
7Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
Pin Descriptions (continued)
Detailed Description
The MAX16963 is a high-efficiency, dual synchronous
step-down converter that operates with a 2.7V to 5.5V
input voltage range and provides a 0.8V to 3.6V output
voltage range. The MAX16963 delivers up to 1.5A of load
current per output and achieves Q3% output error over
load, line, and temperature ranges.
The device features a PWM input that, when set to
logic-high, forces the MAX16963 into a fixed-frequency,
2.2MHz PWM mode. A logic-low at the PWM input
enables the device to enter a low-power pulse frequency
modulation mode (PFM) under light-load conditions. An
optional spread-spectrum frequency modulation mini-
mizes radiated electromagnetic emissions due to the
switching frequency and a factory programmable syn-
chronization I/O (SYNC) allows better noise immunity.
On-board low RDSON switches help minimize efficiency
losses at heavy loads and reduce critical/parasitic
inductance, making the layout a much simpler task with
respect to discrete solutions. Following a simple layout
and footprint ensures first-pass success in new designs.
The device is offered in factory-preset output volt-
ages to allow customers to achieve Q3% output-voltage
accuracy without using expensive Q1% resistors. In
addition, the adjustable output-voltage versions can be
set to any desired values between 0.8V to 3.6V using
an external resistive divider. See the Selector Guide for
available options.
Additional features include 8ms fixed soft-start, 16ms
fixed power-good output, overcurrent, and overtempera-
ture protections. See Figure 1.
Power-Good Output
The MAX16963 features an open-drain power-good out-
put that asserts when the output voltage drops 8% below
the regulated voltage. PG_ remains asserted for a fixed
16ms timeout period after the output rises up to its regulat-
ed voltage. Connect PG_ to OUTS_ with a 10kI resistor.
Soft-Start
The MAX16963 includes an 8ms fixed soft-start time.
Soft-start time limits startup inrush current by forcing the
output voltage to ramp up towards its regulation point.
Spread-Spectrum Option
The MAX16963 featuring spread-spectrum (SS) opera-
tion varies the internal operating frequency up by SS
= 6% relative to the internally generated operating fre-
quency of 2.2MHz (typ). This function does not apply
to externally applied oscillation frequency. The internal
oscillator is frequency modulated with a 6% frequency
deviation. See the Selector Guide for available options.
Synchronization (SYNC)
SYNC is a factory-programmable I/O. See the Selector
Guide for available options. When SYNC is configured
as an input, a logic-high on PWM enables SYNC to
accept signal frequency in the range of 1.7MHz < fSYNC
< 2.5MHz. When SYNC is configured as an output, a
logic-high on PWM enables SYNC to output a 90N phase-
shifted signal with respect to internal oscillator.
PIN NAME FUNCTION
TQFN TSSOP
12 14 PV Device Supply Voltage Input. Bypass with at least a 1FF ceramic capacitor to GND. In addition,
connect a 10I decoupling resistor between PV and the bypass capacitor.
13 15 PG2 OUT2 Power-Good Output. Open-drain output. PG2 asserts when VOUT2 drops by 8%. Connect
to a 10kI pullup resistor.
14 16 OUTS2 Converter #2 Feedback Input (Adjustable Output Option Only). Connect an external resistive
divider from VOUT2 to OUTS2 and GND to set the output voltage.
15 1 EN2 Converter #2 Enable Input. Drive EN2 high to enable converter #2. Drive EN2 low to disable
converter #2.
16 2 PV2 Converter #2 Input Supply. Bypass PV2 with at least a 4.7FF ceramic capacitor to PGND2.
— — EP Exposed Pad. Connect EP to a large-area contiguous copper ground plane for effective power
dissipation. Do not use as the only IC ground connection. EP must be connected to GND.
8Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
Figure 1. Internal Block Diagram
MAX16963
CONTROL LOGIC
STEP-DOWN #1
SKIP CURRENT
COMP
CURRENT-SENSE
AMP
PEAK CURRENT
COMP
RAMP
GENERATOR
PMW
COMP
POWER-GOOD
COMP
ERROR
AMP FPWM
P1-OK
ZERO-CROSSING
COMP
OUTS1
SYNC
EN1
P2-OK
CLK1
PV1
PV1
LX1
PGND1
PG1
PGND1
CLK1
CLK1
CLK2
FPWM
EN2
P1-OK
CURRENT LIM
COMP
Σ
SOFT-START
GENERATOR
VREF
VOLTAGE
REFERENCE
TH-SD
FEEDBACK
DRIVER
OSC.
MAIN
CONTROL
LOGIC
TRIM BITS
VREF
OTP
PV
PGND1
PG2
GND
CONTROL LOGIC
STEP-DOWN #2
SKIP CURRENT
COMP
CURRENT-SENSE
AMP
PEAK CURRENT
COMP
RAMP
GENERATOR
PMW
COMP
POWER-GOOD
COMP
ERROR
AMP FPWM
P2-OK
ZERO-CROSSING
COMP
OUTS1
CLK2
PV1
PV2
LX2
PGND2
PGND2
CLK2
CURRENT LIM
COMP
Σ
SOFT-START
GENERATOR
VREF
FEEDBACK
DRIVER
PV
PGND2
9Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
Current-Limit/Short-Circuit Protection
The MAX16963 features current limit that protects the
device against short-circuit and overload conditions at an
output. In the event of a short-circuit or overload condi-
tion at an output, the high-side MOSFET remains on until
the inductor current reaches the high-side MOSFET’s
current-limit threshold. The converter then turns on the
low-side MOSFET and the inductor current ramps down.
The converter allows the high-side MOSFET to turn on
only when the inductor current ramps down to the low-
side MOSFET’s current threshold. This cycle repeats until
the short or overload condition is removed.
FPWM/Skip Modes
The MAX16963 features an input (PWM) that puts the
converter either in skip mode for forced PWM (FPWM)
mode of operation. See the Pin Descriptions for mode
detail. In FPWM mode, the converter switches at a con-
stant frequency with variable on-time. In skip mode, the
converter’s switching frequency is load-dependent until
the output load reaches a certain threshold. At higher
load current, the switching frequency does not change
and the operating mode is similar to the FPWM mode.
Skip mode helps improve efficiency in light-load appli-
cations by allowing the converters to turn on the high-
side switch only when the output voltage falls below a
set threshold. As such, the converter does not switch
MOSFETs on and off as often as is the case in the FPWM
mode. Consequently, the gate charge and switching
losses are much lower in skip mode.
Overtemperature Protection
Thermal overload protection limits the total power dissi-
pation in the MAX16963. When the junction temperature
exceeds 165°C (typ), an internal thermal sensor shuts
down the internal bias regulator and the step-down
controller, allowing the IC to cool. The thermal sensor
turns on the IC again after the junction temperature cools
by 15°C.
Applications Information
Adjustable Output-Voltage Option
The MAX16963 has an adjustable output voltage (see
the Selector Guide for options) that allows the customer
to set the outputs to any voltage between 0.8V and 3.6V.
Connect a resistive divider from output (VOUT_) to OUTS_
to GND to set the output voltage (Figure 2). Select R2
(OUTS_ to GND resistor) less than or equal to 100kI.
Calculate R1 (VOUT_ to OUTS_ resistor) with the follow-
ing equation:
= −
×≤Ω
+
OUT_
OUTS_
V
R1 R2 1
V
R1 R2
where 7.5k
R1 R2
where VOUTS_ = 800mV (see the Electrical Characteristics
table).
The external feedback resistive divider must be frequency
compensated for proper operation. Place a capacitor
across each resistor in the resistive divider network.
Use the following equation to determine the value of the
capacitors:
=
R2
C1 10pF R1
Connect OUTS_ to VOUT_ for the fixed output-voltage
versions.
Inductor Selection
Three key inductor parameters must be specified for
operation with the MAX16963: inductance value (L),
inductor saturation current (ISAT), and DC resistance
(RDCR). Use the following formulas to determine the mini-
mum inductor value:
( )
=−× ×
××
OUT_
MIN1 IN OUT_ IN OP REF CS
V3
L VV V fV G
where fOP is the operating frequency; this value is 2.2MHz,
unless externally synchronized to a different frequency;
VREF is the reference voltage equal to 1.25V; GCS is the
internal current-sense conductance equal to 0.8.
The next equation ensures that the inductor current down
slope is less than the internal slope compensation. For
Figure 2. Adjustable Output Voltage Setting
MAX16963
OUTS_
R1
R2
C1
VOUT_
10Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
this to be the case, the following equation needs to be
satisfied:
−≥
m2
m2
where m2 is the inductor current down slope:
OUT
V
L
and -m is the slope compensation:
×
µ×
REF
CS
0.8 V
sG
Solving for L:
µ
= ×
××
MIN2 OUT REF CS
s
LV
1.6 V G
The equation that provides the bigger inductor value
must be chosen for proper operation.
=
MIN MIN1 MIN2
L max(L , L )
Then:
= ×
MAX MIN
L 2L
The maximum inductor value must not exceed the cal-
culated value from the above formula. This ensures that
the current feedback loop receives the correct amount of
current ripple for proper operation.
Table 1 lists some of the inductor values for 1.5A output
current and several output voltages.
Input Capacitor
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
ripple on the input caused by the circuit’s switching.
The input capacitor RMS current requirement (IRMS) is
defined by the following equation:
( )
OUT_ PV_ OUT_
RMS LOAD(MAX) PV_
VVV
II V
−
=
IRMS has a maximum value when the input voltage
equals twice the output voltage (VPV_ = 2VOUT_), so
IRMS(MAX) = ILOAD(MAX)/2.
Choose an input capacitor that exhibits less than +10NC
self-heating temperature rise at the RMS input current for
optimal long-term reliability.
The input-voltage ripple is composed of DVQ (caused
by the capacitor discharge) and DVESR (caused by the
ESR of the capacitor). Use low-ESR ceramic capacitors
with high-ripple current capability at the input. Assume
the contribution from the ESR and capacitor discharge
equal to 50%. Calculate the input capacitance and ESR
required for a specified input voltage ripple using the fol-
lowing equations:
ESR
IN L
OUT_
V
ESR I
I
2
∆
=∆
+
where:
( )
PV_ OUT_ OUT_
LPV_ SW
VV V
IV fL
−×
∆= ××
and:
OUT_
IN Q SW
I D(1 D)
CVf
×−
=∆×
and
OUT_
PV_
V
DV
=
where IOUT_ is the maximum output current, and D is the
duty cycle.
Table 1. Inductor Values vs. (VIN - VOUT)
VIN - VOUT (V) 5.5 to 3.3 5.5 to 2.5 5.5 to 1.5 3.0 to 0.8
INDUCTOR (µH), ILOAD = 1.5A 1.5 1.5 1.0 0.68
11Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
Output Capacitor
The minimum capacitor required depends on output
voltage, maximum device current capability, and the
error-amplifier voltage gain. Use the following formula to
determine the required output capacitor value:
×
=π× × ×
=π× × Ω
REF EAMP
OUT(MIN) CO OUT CS
OUT
V xG
C2f V R
0.8V x 31.7
2 210kHz V 378m
where fCO is the target crossover frequency equal to
210kHz, GEAMP is the error-amplifier voltage gain equal to
31.7V/V, and RCS is 378mΩ.
PCB Layout Guidelines
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. Use a multilayer
board whenever possible for better noise immunity and
power dissipation. Follow these guidelines for good PCB
layout:
1) Use a large contiguous copper plane under the
MAX16963 package. Ensure that all heat-dissipating
components have adequate cooling. The bottom
pad of the MAX16963 must be soldered down to
this copper plane for effective heat dissipation and
maximizing the full power out of the MAX16963. Use
multiple vias or a single large via in this plane for
heat dissipation.
2) Isolate the power components and high current path
from the sensitive analog circuitry. This is essential to
prevent any noise coupling into the analog signals.
3) Add small footprint blocking capacitors with low self-
resonance frequency close to PV1, PV2, and PV.
4) Keep the high-current paths short, especially at the
ground terminals. This practice is essential for stable,
jitter-free operation. The high current path composed
of input capacitors at PV1 and PV2, inductor, and the
output capacitor should be as short as possible.
5) Keep the power traces and load connections short.
This practice is essential for high efficiency. Use
thick copper PCBs (2oz vs. 1oz) to enhance full-load
efficiency.
6) OUTS_ are sensitive to noise for devices with external
feedback option. The resistive network, R1, R2, and
C1 must be placed close to OUTS_ and far away from
the LX_ node and high switching current paths. The
ground node of R2 must be close to GND.
7) The ground connection for the analog and power
section should be close to the IC. This keeps the
ground current loops to a minimum. In cases where
only one ground is used enough isolation between
analog return signals and high power signals must
be maintained.
Package Information
For the latest package outline information and land patterns (foot-
prints), go to www.maximintegrated.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
Chip Information
PROCESS: BiCMOS
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
16 TQFN-EP T1644+4 21-0139 90-0070
16 TSSOP-EP U16E+3 21-0108 90-0120
12Maxim Integrated
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
Ordering Information
/V denotes an automotive qualified part.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Selector Guide
Note: Contact the factory for variants with different output voltage, spread spectrum, and power-good delay time settings.
PART TEMP RANGE LOAD CURRENT CAPABILITY
PER OUTPUT (A) PIN-PACKAGE
MAX16963_ATE_/V+ -40°C to +125°C 1.5/1.5 16 TQFN-EP*
MAX16963_AUE_/V+ -40°C to +125°C 1.5/1.5 16 TSSOP-EP*
ROOT PART PACKAGE
SUFFIX
OPTION
SUFFIX
ILOAD PER
OUTPUT (A)
OUTPUT
VOLTAGE
SPREAD
SPECTRUM
SYNC IN/
OUT
POWER-GOOD
DELAY (ms)
MAX16963 RAUE A/V+ 1.5/1.5 Ext. Adj. Disabled In 16
MAX16963 SAUE A/V+ 1.5/1.5 Ext. Adj. Enabled In 16
MAX16963 RATE A/V+ 1.5/1.5 Ext. Adj. Disabled In 16
MAX16963 SATE A/V+ 1.5/1.5 Ext. Adj. Enabled In 16
MAX16963 SATE C/V+ 1.5/1.5 Ext. Adj. Enabled Out 16
MAX16963 SATE D/V+ 1.5/1.5 Ext. Adj. Enabled In 8
MAX16963 SATE F/V+ 1.5/1.5 Ext. Adj. Enabled Out 8
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 13
© 2015 Maxim Integrated Products, Inc. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX16963
Dual 2.2MHz, Low-Voltage Step-Down
DC-DC Converter
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 11/12 Initial release —
1 9/13 Updated input voltage high min spec and input voltage low max spec, Figure 2,
equation, step 6 in the PCB Layout Guidelines section, and the Ordering Information 4, 9, 11, 12
2 10/13 Updated Ordering Information and added MAX16963SATE/V+ and PG timing
column to Selector Guide 12
3 2/14
Added FB regulation voltage to the Electrical Characteristics table, corrected VOUT
mismatch in the Typical Operating Characteristic section, updated Inductor Selection
and Output Capacitor sections, updated Table 2, updated note in the Selector Guide
2, 3, 5,
9, 10, 12
4 4/14 Updated VPV_ condition for PG_ output low voltage specification 4
5 7/15 Added formula to equation in the Setting the Output Voltage section, replaced the
Output Capacitor section, and deleted Table 2 9–11
Mouser Electronics
Authorized Distributor
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Maxim Integrated:
MAX16963SATEA/V+ MAX16963SAUEA/V+ MAX16963RAUEA/V+ MAX16963RATEA/V+T MAX16963RATEA/V+
MAX16963SATEC/V+T MAX16963SATEF/V+ MAX16963SATED/V+T MAX16963SATEF/V+T MAX16963SATED/V+
MAX16963SATEC+ MAX16963SATEC/V+
