REV. G
AD7416/AD7417/AD7418
10-Bit Digital Temperature Sensor (AD7416) and
Four Single-Channel ADCs (AD7417/AD7418)
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 www.analog.com
Fax: 781/326-8703 © 2004 Analog Devices, Inc. All rights reserved.
FEATURES
10-Bit ADC with 15 ␮s and 30 ␮s Conversion Times
Single and Four Single-Ended Analog Input Channels
On-Chip Temperature Sensor: –40ⴗC to +125ⴗC
On-Chip Track-and-Hold
Overtemperature Indicator
Automatic Power-Down at the End of a Conversion
Wide Operating Supply Range: 2.7 V to 5.5 V
I2C® Compatible Serial Interface
Selectable Serial Bus Address Allows Connection of up
to Eight AD7416/AD7417s to a Single Bus
AD7416 Is a Superior Replacement for LM75
APPLICATIONS
Data Acquisition with Ambient Temperature Monitoring
Industrial Process Control
Automotive
Battery-Charging Applications
Personal Computers
FUNCTIONAL BLOCK DIAGRAMS
VDD
OTI
GND
SDA
SCL
FAULT
QUEUE
COUNTER
SETPOINT
COMPARATOR
TOTI SETPOINT
REGISTER
THYST SETPOINT
REGISTER
TEMPERATURE
VALUE
REGISTER
A0
A1
A2
CONFIGURATION
REGISTER
SERIAL BUS
INTERFACE
BAND GAP
TEMPERATURE
SENSOR
10-BIT
ANALOG-DIGITAL
CONVERTER
ADDRESS
POINTER
REGISTER
AD7416
CONTROL
LOGIC
A > B
REF
IN
V
DD
OTI
SCL
SDA
A2A1A0
CONVST
A
IN1
A
IN2
A
IN3
A
IN4
+
TEMP
SENSOR
SAMPLING
CAPACITOR
V
BALANCE
CLOCK
A
B
REF
2.5V
CHARGE
DISTRIBUTION
DAC
I
2
C
INTERFACE
MUX
OVERTEMP REG
NC NC GND
DATA OUT
NC = NO CONNECT
AD7417
CONTROL
LOGIC
A > B
V
DD
OTI
SCL
SDA
A
IN1
+
SAMPLING
CAPACITOR
V
BALANCE
CLOCK
A
B
I
2
C
INTERFACE
MUX
OVERTEMP REG
GND
DATA OUT
TEMP
SENSOR
REF
IN
CONVST
REF
2.5V CHARGE
DISTRIBUTION
DAC
AD7418
GENERAL DESCRIPTION
The AD7417 and AD7418 are 10-bit, 4-channel and single-
channel ADCs with an on-chip temperature sensor that
can operate from a single 2.7 V to 5.5 V power supply. The
devices contain a 15 µs successive approximation converter, a
5-channel multiplexer, a temperature sensor, a clock oscilla-
tor, a track-and-hold, and a reference (2.5 V). The AD7416
is a temperature-monitoring only device in an 8-lead package.
The temperature sensor on the parts can be accessed via multi-
plexer Channel 0. When Channel 0 is selected and a conversion
is initiated, the resulting ADC code at the end of the conversion
gives a measurement of the ambient temperature (±1°C @ 25°C).
On-chip registers can be programmed with high and low tem-
perature limits, and an open-drain overtemperature indicator
(OTI) output is provided, which becomes active when a pro-
grammed limit is exceeded.
A configuration register allows programming of the sense of the
OTI output (active high or active low) and its operating mode
(comparator or interrupt). A programmable fault queue counter
allows the number of out-of-limit measurements that must occur
before triggering the OTI output to be set to prevent spurious
triggering of the OTI output in noisy environments.
(continued on page 7)
REV. G–2–
AD7416/AD7417/AD7418
(VDD = 2.7 V to 5.5 V, GND = 0 V, REFIN = 2.5 V, unless otherwise noted.)
Parameter A Version B Version
1
Unit Test Conditions/Comments
DC ACCURACY Any Channel.
Resolution 10 10 Bits
Minimum Resolution for Which No
Missing Codes Are Guaranteed 10 10 Bits
Relative Accuracy
2
±1±1LSB max This Specification Is Typical for V
DD
of
3.6 V to 5.5 V.
Differential Nonlinearity
2
±1±1LSB max This Specification Is Typical for V
DD
of
3.6 V to 5.5 V.
Gain Error
2
±3±3LSB max External Reference.
±10 ±10 LSB max Internal Reference.
Gain Error Match
2
±0.6 ±0.6 LSB max AD7417 Only.
Offset Error
2
±4±4LSB max
Offset Error Match ±0.7 ±0.7 LSB max AD7417 Only.
ANALOG INPUTS
Input Voltage Range V
REF
V
REF
V max
00 V min
Input Leakage Current
3
±1±1µA max
Input Capacitance 10 10 pF max
TEMPERATURE SENSOR
1
Measurement Error
Ambient Temperature 25°C±2±1°C max
T
MIN
to T
MAX
±3±2°C max
Temperature Resolution 1/4 1/4 °C/LSB
CONVERSION RATE
Track-and-Hold Acquisition Time
4
400 400 ns max Source Impedance < 10 Ω.
Conversion Time
Temperature Sensor 30 30 µs max Typically 27 µs.
Channels 1 to 4 15 15 µs max Typically 10 µs.
REFERENCE INPUT
5, 6
REF
IN
Input Voltage Range
6
2.625 2.625 V max 2.5 V + 5%.
2.375 2.375 V min 2.5 V – 5%.
Input Impedance 40 40 kΩ min
Input Capacitance 10 10 pF max
ON-CHIP REFERENCE Nominal 2.5 V.
Reference Error
6
±25 ±25 mV max
Temperature Coefficient
6
80 80 ppm/°C typ
DIGITAL INPUTS
Input High Voltage, V
IH
V
DD
× 0.7 V
DD
× 0.7 V min
Input Low Voltage, V
IL
V
DD
× 0.3 V
DD
× 0.3 V max
Input Leakage Current 1 1 µA max
DIGITAL OUTPUTS
Output Low Voltage, V
OL
0.4 0.4 V max I
OL
= 3 mA.
Output High Current 1 1 µA max V
OH
= 5 V.
POWER REQUIREMENTS
V
DD
5.5 5.5 V max For Specified Performance.
2.7 2.7 V min
I
DD
Logic Inputs = 0 V or V
DD.
Normal Operation 600 600 µA max
Power-Down 1 1 µA max 50 nA Typically.
Auto Power-Down Mode V
DD
= 3 V. See Operating Modes.
10 SPS Throughput Rate 6 6 µW typ
1 kSPS Throughput Rate 60 60 µW typ
10 kSPS Throughput Rate 600 600 µW typ
Power-Down 3 3 µW max Typically 0.15 µW.
AD7417/AD7418–SPECIFICATIONS
REV. G
AD7416/AD7417/AD7418
–3–
NOTES
1
B Version applies to AD7417 only with temperature range of –40°C to +85°C. A Version temperature range is –40°C to +125°C. For V
DD
= 2.7 V, T
A
= 85°C max
and temperature sensor measurement error = ±3°C.
2
See Terminology.
3
Refers to the input current when the part is not converting. Primarily due to reverse leakage current in the ESD protection diodes.
4
Sample tested during initial release and after any redesign or process change that may affect this parameter.
5
On-chip reference shuts down when external reference is applied.
6
The accuracy of the temperature sensor is affected by reference tolerance. The relationship between the two is explained in the Temperature Sensor section.
Specifications subject to change without notice.
AD7416–SPECIFICATIONS
(VDD = 2.7 V to 5.5 V, GND = 0 V, REFIN = 2.5 V, unless otherwise noted.)
Parameter Min Typ Max Unit Test Conditions/Comments
TEMPERATURE SENSOR AND ADC
Accuracy ±2.0 °CT
A
= –25°C to +100°C
(V
DD
= 3 V min)
1
±3.0 °CT
A
= –40°C to +125°C
(V
DD
= 3 V min)
1
Resolution 10 Bits
Temperature Conversion Time 40 µs
Update Rate, t
R
400 µs
OTI Delay 1 × t
R
6 × t
R
ms Depends on Fault Queue Setting
Supply Current 1.0 mA I
2
C Active
350 600 µAI
2
C Inactive
0.2 1.5 µAShutdown Mode
T
OTI
Default Temperature 80 °C
T
HYST
Default Temperature 75 °C
DIGITAL INPUTS
Input High Voltage, V
IH
V
DD
× 0.7 V
DD
+ 0.5 V
Input Low Voltage, V
IL
–0.3 V
DD
× 0.3 V
Input High Current, I
IH
+0.005 +1.0 µAV
IN
= 5 V
Input Low Current, I
IL
–0.005 –1.0 µAV
IN
= 0 V
Input Capacitance, C
IN
20 pF All Digital Inputs
DIGITAL OUTPUTS
Output Low Voltage, V
OL
0.4 V I
OL
= 3 mA
Output High Current 1 µAV
OH
= 5 V
Output Fall Time, t
f
250 ns C
L
= 400 pF, I
O
= 3 mA
OS Output Low Voltage, V
OL
0.8 V I
OUT
= 4 mA
AC ELECTRICAL CHARACTERISTICS
2
AD7416/AD7417/AD7418
Serial Clock Period, t
1
2.5 µsSee Figure 1
Data In Setup Time to SCL High, t
2
50 ns See Figure 1
Data Out Stable after SCL Low, t
3
0nsSee Figure 1
SDA Low Setup Time to SCL Low
(Start Condition), t
4
50 ns See Figure 1
SDA High Hold Time after SCL High
(Stop Condition), t
5
50 ns See Figure 1
SDA and SCL Fall Time, t
6
300 ns See Figure 1
NOTES
1
For V
DD
= 2.7 V to 3 V, T
A
max = 85°C and accuracy = ±3°C.
2
Sample tested during initial release and after any redesign or process change that may affect this parameter.
Specifications subject to change without notice.
t
4
t
2
t
3
t
5
SCL
SDA
DATA IN
SDA
DATA OUT
t
6
t
1
Figure 1. Diagram for Serial Bus Timing
REV. G–4–
AD7416/AD7417/AD7418
AD7417 PIN FUNCTION DESCRIPTION
Pin No. Mnemonic Description
1, 16 NC No Connection. Do not connect anything to this pin.
2SDA Digital I/O. Serial bus bidirectional data. Push-pull output.
3SCL Digital Input. Serial bus clock.
4OTI This is a logic output. The overtemperature indicator (OTI) is set if the result of a conversion on
Channel 0 (temperature sensor) is greater than an 8-bit word in the overtemperature register (OTR).
The signal is reset at the end of a serial read operation. Open-drain output.
5REF
IN
Reference Input. An external 2.5 V reference can be connected to the AD7417 at this pin. To enable the
on-chip reference, the REFIN pin should be tied to GND. If an external reference is connected to the
AD7417, the internal reference will shut down.
6GND Ground reference for track-and-hold, comparator and capacitor DAC, and digital circuitry.
7–10 A
IN1
to A
IN4
Analog Input Channels. The AD7417 has four analog input channels. The input channels are single-ended
with respect to GND. The input channels can convert voltage signals in the range 0 V to V
REF
. A chan-
nel is selected by writing to the configuration register of the AD7417. (See Control Byte section.)
11 A2 Digital Input. The highest programmable bit of the serial bus address.
12 A1 Digital Input. The middle programmable bit of the serial bus address.
13 A0 Digital Input. The lowest programmable bit of the serial bus address.
14 V
DD
Positive Supply Voltage, 2.7 V to 5.5 V.
15 CONVST Logic Input Signal. Convert start signal. The rising edge of this signal fully powers up the part. The
power-up time for the part is 4 µs. If the CONVST pulse is greater than 4 µs, the falling edge of CONVST
places the track-and-hold mode into hold mode and initiates a conversion. If the pulse is less than 4 µs,
an internal timer ensures that the track-and-hold does not go into hold and conversion is not initiated
until the power-up time has elapsed. The track-and-hold goes into track mode again at the end of con-
version. (See Operating Mode section.)
AD7417 PIN CONFIGURATION
SOIC/TSSOP
TOP VIEW
(Not to Scale)
NC = NO CONNECT
NC
SDA
SCL
OTI
REF
IN
GND
A
IN1
A
IN2
NC
CONVST
V
DD
A0
A1
A2
A
IN4
A
IN3
AD7417
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
REV. G
AD7416/AD7417/AD7418
–5–
AD7416 PIN FUNCTION DESCRIPTION
Pin No. Mnemonic Description
1SDA Digital I/O. Serial bus bidirectional data. Push-pull output.
2SCL Digital Input. Serial bus clock.
3OTI This is a logic output. The OTI is set if the result of a conversion on Channel 0 (temperature sensor) is
greater that an 8-bit word in the OTR. The signal is reset at the end of a serial read operation. Open-
drain output.
4GND Ground reference for track-and-hold, comparator and capacitor DAC, and digital circuitry.
5A2Digital Input. The highest programmable bit of the serial bus address.
6A1Digital Input. The middle programmable bit of the serial bus address.
7A0Digital Input. The lowest programmable bit of the serial bus address.
8V
DD
Positive Supply Voltage, 2.7 V to 5.5 V.
AD7418 PIN FUNCTION DESCRIPTION
Pin No. Mnemonic Description
1SDA Digital I/O. Serial bus bidirectional data. Push-pull output.
2SCL Digital Input. Serial bus clock.
3OTI This is a logic output. The OTI is set if the result of a conversion on Channel 0 (temperature sensor) is
greater that an 8-bit word in the OTR. The signal is reset at the end of a serial read operation. Open-
drain output.
4GND Ground reference for track-and-hold, comparator and capacitor DAC, and digital circuitry.
5A
IN
Analog Input Channel. The input channel is single-ended with respect to GND. The input channel can
convert voltage signals in the range 0 V to V
REF
. The analog input channel is selected by writing to the
configuration register of the AD7418 and choosing Channel 4. (See Control Byte section.)
6REF
IN
Reference Input. An external 2.5 V reference can be connected to the AD7418 at this pin. To enable the
on-chip reference, the REF
IN
pin should be tied to GND. If an external reference is connected to the
AD7418, the internal reference will shut down.
7V
DD
Positive Supply Voltage, 2.7 V to 5.5 V.
8CONVST Logic Input Signal. Convert start signal. The rising edge of this signal fully powers up the part. The
power-up time for the part is 4 µs. If the CONVST pulse is greater than 4 µs, the falling edge of
CONVST places the track-and-hold mode into hold mode and initiates a conversion. If the pulse is less
than 4 µs, an internal timer ensures that the track-and-hold does not go into hold and conversion is not
initiated until the power-up time has elapsed. The track-and-hold goes into track mode again at the end
of conversion. (See Operating Mode section.)
AD7416 PIN CONFIGURATION
SOIC/MSOP
TOP VIEW
(Not to Scale)
8
7
6
5
1
2
3
4
SDA
SCL
OTI
GND
VDD
A0
A2
AD7416
A1
AD7418 PIN CONFIGURATION
SOIC/MSOP
TOP VIEW
(Not to Scale)
8
7
6
5
1
2
3
4
SDA
SCL
OTI
GND
CONVST
VDD
REFIN
AIN
AD7418
REV. G–6–
AD7416/AD7417/AD7418
ABSOLUTE MAXIMUM RATINGS
1
(T
A
= 25°C, unless otherwise noted.)
V
DD
to AGND . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V
V
DD
to DGND . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V
Analog Input Voltage to AGND
A
IN1
to A
IN4
. . . . . . . . . . . . . . . . . . . –0.3 V to V
DD
+ 0.3 V
Reference Input Voltage to AGND
2
. . –0.3 V to V
DD
+ 0.3 V
Digital Input Voltage to DGND . . . . . –0.3 V to V
DD
+ 0.3 V
Digital Output Voltage to DGND . . . . –0.3 V to V
DD
+ 0.3 V
Operating Temperature Range
A Version . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +125°C
B Version . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . 150°C
TSSOP, Power Dissipation . . . . . . . . . . . . . . . . . . . . 450 mW
␪
JA
Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 120°C/W
Lead Temperature, Soldering . . . . . . . . . . . . . . . . . . 260°C
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C
16-Lead SOIC Package, Power Dissipation . . . . . . . . 450 mW
␪
JA
Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 100°C/W
Lead Temperature, Soldering
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C
8-Lead SOIC Package, Power Dissipation . . . . . . . . . 450 mW
␪
JA
Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 157°C/W
Lead Temperature, Soldering
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C
MSOP Package, Power Dissipation . . . . . . . . . . . . . . 450 mW
␪
JA
Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 206°C/W
Lead Temperature, Soldering
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C
NOTES
1
Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
2
If the reference input voltage is likely to exceed V
DD
by more than 0.3 V (e.g.,
during power-up) and the reference is capable of supplying 30 mA or more, it is
recommended to use a clamping diode between the REF
IN
pin and V
DD
pin. The
diagram below shows how the diode should be connected.
REFIN VDD
AD7417
BAT81
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although the
AD7416/AD7417/AD7418 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions
are recommended to avoid performance degradation or loss of functionality.
REV. G
AD7416/AD7417/AD7418
–7–
ORDERING GUIDE
Temperature Temperature Package Package
Model Range Error Description Branding Option
AD7416ACHIPS Die
AD7416AR –40°C to +125°C±2°C8-Lead Standard Small Outline Package (SOIC) RN-8
AD7416AR-REEL –40°C to +125°C±2°C8-Lead Standard Small Outline Package (SOIC) RN-8
AD7416AR-REEL7 –40°C to +125°C±2°C8-Lead Standard Small Outline Package (SOIC) RN-8
AD7416ARZ*–40°C to +125°C±2°C8-Lead Standard Small Outline Package (SOIC) RN-8
AD7416ARZ-REEL*–40°C to +125°C±2°C8-Lead Standard Small Outline Package (SOIC) RN-8
AD7416ARZ-REEL7*–40°C to +125°C±2°C8-Lead Standard Small Outline Package (SOIC) RN-8
AD7416ARM –40°C to +125°C±2°C8-Lead Micro Small Outline Package (MSOP) C6A RM-8
AD7416ARM-REEL –40°C to +125°C±2°C8-Lead Micro Small Outline Package (MSOP) C6A RM-8
AD7416ARM-REEL7 –40°C to +125°C±2°C8-Lead Micro Small Outline Package (MSOP) C6A RM-8
AD7416ARMZ*–40°C to +125°C±2°C8-Lead Micro Small Outline Package (MSOP) C6A RM-8
AD7416ARMZ-REEL*–40°C to +125°C±2°C8-Lead Micro Small Outline Package (MSOP) C6A RM-8
AD7416ARMZ-REEL7*–40°C to +125°C±2°C8-Lead Micro Small Outline Package (MSOP) C6A RM-8
AD7417ACHIPS Die
AD7417AR –40°C to +125°C±2°C16-Lead Standard Small Outline Package (SOIC) RN-16
AD7417AR-REEL –40°C to +125°C±2°C16-Lead Standard Small Outline Package (SOIC) RN-16
AD7417AR-REEL7 –40°C to +125°C±2°C16-Lead Standard Small Outline Package (SOIC) RN-16
AD7417ARU –40°C to +125°C±2°C16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7417ARU-REEL –40°C to +125°C±2°C16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7417ARU-REEL7 –40°C to +125°C±2°C16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7417BR –40°C to +85°C±1°C16-Lead Standard Small Outline Package (SOIC) RN-16
AD7417BR-REEL –40°C to +85°C±1°C16-Lead Standard Small Outline Package (SOIC) RN-16
AD7417BR-REEL7 –40°C to +85°C±1°C16-Lead Standard Small Outline Package (SOIC) RN-16
AD7418ACHIPS Die
AD7418AR –40°C to +125°C±2°C8-Lead Standard Small Outline Package (SOIC) RN-8
AD7418AR-REEL –40°C to +125°C±2°C8-Lead Standard Small Outline Package (SOIC) RN-8
AD7418AR-REEL7 –40°C to +125°C±2°C8-Lead Standard Small Outline Package (SOIC) RN-8
AD7418ARM –40°C to +125°C±2°C8-Lead Micro Small Outline Package (MSOP) C7A RM-8
AD7418ARM-REEL –40°C to +125°C±2°C8-Lead Micro Small Outline Package (MSOP) C7A RM-8
AD7418ARM-REEL7 –40°C to +125°C±2°C8-Lead Micro Small Outline Package (MSOP) C7A RM-8
AD7418ARUZ*–40°C to +125°C±2°C16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7418ARUZ-REEL*–40°C to +125°C±2°C16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7418ARUZ-REEL7*–40°C to +125°C±2°C16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
EVAL-AD7416/AD7417/ Evaluation Board
AD7418EB
*Pb-Free Part
REV. G–8–
AD7416/AD7417/AD7418
(continued from page 1)
An I
2
C compatible serial interface allows the AD7416/AD7417/
AD7418 registers to be written to and read back. The three LSBs
of the AD7416/AD7417’s serial bus address can be selected,
which allows up to eight AD7416/AD7417s to be connected to
a single bus.
The AD7417 is available in a narrow body, 0.15'', 16-lead, small
outline IC (SOIC) and in a 16-lead, thin shrink, small outline
package (TSSOP). The AD7416 and AD7418 are available in
8-lead SOIC and MSOP packages.
PRODUCT HIGHLIGHTS
1. The AD7416/AD7417/AD7418 have an on-chip temperature
sensor that allows an accurate measurement of the ambient
temperature (±1°C @ 25°C, ±2°C overtemperature) to be
made. The measurable temperature range is –40°C to +125°C.
An overtemperature indicator is implemented by carrying
out a digital comparison of the ADC code for Channel 0
(temperature sensor) with the contents of the on-chip over-
temperature register.
2. The AD7417 offers a space-saving 10-bit A/D solution with
four external voltage input channels, an on-chip temperature
sensor, an on-chip reference, and clock oscillator.
3. The automatic power-down feature enables the AD7416/
AD7417/AD7418 to achieve superior power performance. At
slower throughput rates, the part can be programmed to
operate in a low power shutdown mode, allowing further
savings in power consumption.
TERMINOLOGY
Relative Accuracy
Relative accuracy or endpoint nonlinearity is the maximum
deviation from a straight line passing through the endpoints of
the ADC transfer function.
Differential Nonlinearity
This is the difference between the measured and the ideal 1 LSB
change between any two adjacent codes in the ADC.
Offset Error
This is the deviation of the first code transition (0000 . . . 000)
to (0000 . . . 001) from the ideal, i.e., GND + 1 LSB.
Offset Error Match
This is the difference in offset error between any two channels.
Gain Error
This is the deviation of the last code transition (1111 . . . 110)
to (1111 . . . 111) from the ideal, i.e., VREF – 1 LSB, after the
offset error has been adjusted out.
Gain Error Match
This is the difference in gain error between any two channels.
Track-and-Hold Acquisition Time
Track-and-hold acquisition time is the time required for the
output of the track-and-hold amplifier to reach its final value,
within ±1/2 LSB, after the end of conversion (the point at which
the track-and-hold returns to track mode). It also applies to
situations where a change in the selected input channel takes
place or where there is a step input change on the input voltage
applied to the selected A
IN
input of the AD7417 or AD7418. It
means that the user must wait for the duration of the track-and-
hold acquisition time after the end of conversion or after a channel
change/step input change to A
IN
before starting another conver-
sion, to ensure that the part operates to specification.
CIRCUIT INFORMATION
The AD7417 and AD7418 are single-channel and four-channel,
15 µs conversion time, 10-bit ADCs with on-chip temperature
sensor, reference, and serial interface logic functions on a single
chip. The AD7416 has no analog input channel and is intended
for temperature measurement only. The ADC section consists
of a conventional successive approximation converter based
around a capacitor DAC. The AD7416, AD7417, and AD7418
are capable of running on a 2.7 V to 5.5 V power supply, and
the AD7417 and AD7418 accept an analog input range of 0 V
to +VREF. The on-chip temperature sensor allows an accurate
measurement of the ambient device temperature to be made.
The working measurement range of the temperature sensor is
–40°C to +125°C. The parts require a 2.5 V reference that can
be provided from the part’s own internal reference or from an
external reference source.
CONVERTER DETAILS
Conversion is initiated on the AD7417/AD7418 by pulsing the
CONVST input. The conversion clock for the part is internally
generated so no external clock is required except when reading
from and writing to the serial port. The on-chip track-and-hold
goes from track to hold mode and the conversion sequence is
started on the falling edge of the CONVST signal. A conversion
is also initiated in the automatic conversion mode every time a
read or write operation to the AD7416/AD7417/AD7418 takes
place. In this case, the internal clock oscillator (which runs the
automatic conversion sequence) is restarted at the end of the
read or write operation. The track-and-hold goes into hold
approximately 3 µs after the read or write operation is complete
and a conversion is then initiated. The result of the conversion
is available either 15 µs or 30 µs later, depending on whether an
analog input channel or the temperature sensor is selected. The
track-and-hold acquisition time of the AD7417/AD7418 is 400 ns.
A temperature measurement is made by selecting the Channel 0
of the on-chip mux and carrying out a conversion on this channel.
A conversion on Channel 0 takes 30 µs to complete. Tempera-
ture measurement is explained in the Temperature Measurement
section of this data sheet.
The on-chip reference is not available to the user, but REF
IN
can be overdriven by an external reference source (2.5 V only).
All unused analog inputs should be tied to a voltage within the
nominal analog input range to avoid noise pickup. For mini-
mum power consumption, the unused analog inputs should be
tied to GND.
REV. G
AD7416/AD7417/AD7418
–9–
TYPICAL CONNECTION DIAGRAM
Figure 2 shows a typical connection diagram for the AD7417.
Using the A0, A1, and A2 pins allows the user to select from up
to eight AD7417s on the same serial bus, if desired. An external
2.5 V reference can be connected at the REF
IN
pin. If an exter-
nal reference is used, a 10 µF capacitor should be connected
between REF
IN
and GND. SDA and SCL form the 2-wire I
2
C
compatible interface. For applications where power consump-
tion is of concern, the automatic power-down at the end of a
conversion should be used to improve power performance. See
Operating Modes section of this data sheet.
VDD
AIN1
GND
REFIN
SUPPLY
2.7V TO
5.5V 0.1␮F10␮F
10␮F FOR
EXTERNAL
REFERENCE
OPTIONAL
EXTERNAL
REFERENCE
AD780/
REF-192
0V TO 2.5V
INPUT
CONVST
SDA
AIN2
AIN3
AIN4 OTI
SCL
2-WIRE
SERIAL
INTERFACE
AD7417
A0
A1
A2
␮C/␮P
Figure 2. Typical Connection Diagram
ANALOG INPUTS
Figure 3 shows an equivalent circuit of the analog input struc-
ture of the AD7417 and AD7418. The two diodes, D1 and D2,
provide ESD protection for the analog inputs. Care must be
taken to ensure that the analog input signal never exceeds the
supply rails by more than 200 mV. This will cause these diodes
to become forward-biased and start conducting current into the
substrate. The maximum current these diodes can conduct
without causing irreversible damage to the part is 20 mA. The
capacitor C2 in Figure 3 is typically about 4 pF and can prima-
rily be attributed to pin capacitance. The resistor R1 is a lumped
component made up of the on resistance of a multiplexer and a
switch. This resistor is typically about 1 kΩ. The capacitor C1 is
the ADC sampling capacitor and has a capacitance of 3 pF.
AIN
D1 C1
3pF
VDD
D2
C2
4pF
VBALANCE
CONVERT PHASE – SWITCH OPEN
TRACK PHASE – SWITCH CLOSED
R1
1k⍀
Figure 3. Equivalent Analog Input Circuit
ON-CHIP REFERENCE
The AD7416/AD7417/AD7418 has an on-chip 1.2 V band gap
reference that is gained up by a switched capacitor amplifier to
give an output of 2.5 V. The amplifier is only powered up at the
start of the conversion phase and is powered down at the end of
the conversion. The on-chip reference is selected by connecting
the REF
IN
pin to analog ground. This causes SW1 (see Figure 4)
to open and the reference amplifier to power up during a conver-
sion. Therefore, the on-chip reference is not available externally.
An external 2.5 V reference can be connected to the REF
IN
pin.
This has the effect of shutting down the on-chip reference circuitry.
1.2V
REFIN
SW1
2.5V
EXTERNAL
REFERENCE
DETECT
BUFFER
1.2V
26k⍀
24k⍀
+
+
Figure 4. On-Chip Reference
TEMPERATURE MEASUREMENT
A common method of measuring temperature is to exploit the
negative temperature coefficient of a diode, or the base-emitter
voltage of a transistor, operated at a constant current. Unfortu-
nately, this technique requires calibration to null out the effect
of the absolute value of V
BE
, which varies from device to device.
The technique used in the AD7416/AD7417/AD7418 is to
measure the current change in V
BE
when the device is operated
at two different currents.
This is given by
∆VKTqnN
BE =×
()
/1
where:
K is Boltzmann’s constant.
q is the charge on the electron (1.6 × 10
-19
Coulombs).
T is the absolute temperature in Kelvins.
N is the ratio of the two currents.
IN ⴛ I
V
DD
SENSING
TRANSISTOR
SENSING
TRANSISTOR
V
OUTⴙ
TO ADC
V
OUTⴚ
Figure 5. Temperature Measurement Technique
REV. G–10–
AD7416/AD7417/AD7418
ADDRESS POINTER REGISTER
The Address Pointer Register is an 8-bit register that stores an
address that points to one of the six data registers. The first data
byte of every serial write operation to the AD7416/AD7417/
AD7418 is the address of one of the data registers, which is
stored in the Address Pointer Register, and selects the data
register to which subsequent data bytes are written. Only the
three LSBs of this register are used to select a data register.
Table I. Address Pointer Register
P7*P6*P5*P4*P3*P2 P1 P0
00 000 Register Select
*P3 to P7 must be set to 0.
Table II. Register Addresses
P2 P1 P0 Registers
000Temperature Value (Read-Only)
001Config Register (Read/Write)
010T
HYST
(Read/Write)
011T
OTI
100ADC (AD7417/AD7418 Only)
101Config2 (AD7417/AD7418 Only)
TEMPERATURE VALUE REGISTER (ADDRESS 00h)
The Temperature Value Register is a 16-bit, read-only register
whose 10 MSBs store the temperature reading from the ADC in
10-bit twos complement format. Bits 5 to 0 are unused.
Table III. Temperature Value Register
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6
MSB B8 B7 B6 B5 B4 B3 B2 B1 LSB
The temperature data format is shown in Table IV. This shows
the full theoretical range of the ADC from –128°C to +127°C,
but in practice, the temperature measurement range is limited
to the operating temperature range of the device.
Table IV. Temperature Data Format
Temperature Digital Output
–128°C10 0000 0000
–125°C10 0000 1100
–100°C10 0111 0000
–75°C10 1101 0100
–50°C11 0011 1000
–25°C11 1001 1100
–0.25°C11 1111 1111
0°C00 0000 0000
+0.25°C00 0000 0001
+10°C00 0010 1000
+25°C00 0110 0100
+50°C00 1100 1000
+75°C01 0010 1100
+100°C01 1001 0000
+125°C01 1111 0100
+127°C01 1111 1100
Figure 5 shows the method the AD7416/AD7417/AD7418 uses
to measure the device temperature. To measure ⌬V
BE
, the sen-
sor (substrate transistor) is switched between operating currents
of I and N × I. The resulting waveform is passed through a
chopper-stabilized amplifier that performs the functions of
amplification and rectification of the waveform to produce a dc
voltage proportional to ⌬V
BE
.
This voltage is measured by the ADC to give a temperature
output in 10-bit twos complement form.
The temperature resolution of the ADC is 0.25°C, which corre-
sponds to 1 LSB of the ADC. The ADC can theoretically measure
a temperature span of 255°C; the guaranteed temperature range
is –40°C to +125°C. The result of the conversion is stored in
the Temperature Value Register (00h) as a 16-bit word. The
10 MSBs of this word store the temperature measurement (see
Table III and Table IV).
The temperature conversion formula using the 10 MSBs of the
Temperature Value Register is
1. Positive Temperature = ADC Code/4
2. Negative Temperature = (ADC Code* – 512)/4
*MSB is removed from the ADC Code.
INTERNAL REGISTER STRUCTURE
The AD7417/AD7418 has seven internal registers, as shown in
Figure 6. Six of these are data registers and one is an Address
Pointer Register. The AD7416 has five internal registers (the
ADC and Config2 Registers are not applicable to the AD7416).
T
HYST
SETPOINT
REGISTER
(READ/WRITE
ADDRESS 02h)
CONFIGURATION
REGISTER
(READ/WRITE
ADDRESS 01h)
T
OTI
SETPOINT
REGISTER
(READ/WRITE
ADDRESS 03h)
SERIAL
BUS
INTERFACE
SCL
TEMPERATURE
VALUE
REGISTER
(READ-ONLY
ADDRESS 00h)
ADDRESS POINTER
REGISTER
(SELECTS DATA REGISTER
FOR READ/WRITE)
ADDRESS DATA
CONFIG2
REGISTER
(READ/WRITE
ADDRESS 05h)
ADC
REGISTER
(READ-ONLY
ADDRESS 04h)
SDA
Figure 6. AD7417/AD7418 Register Structure
REV. G
AD7416/AD7417/AD7418
–11–
CONFIGURATION REGISTER (ADDRESS 01h)
The Configuration Register is an 8-bit, read/write register that
is used to set the operating modes of the AD7416/AD7417/
AD7418. Bits D7 to D5 control the channel selection as
outlined in Table VI. These bits should always be 0, 0, 0 for
the AD7416. Bits D4 and D3 are used to set the length of the
fault queue. D2 sets the sense of the OTI output. D1 selects
the comparator or interrupt mode of operation, and D0 = 1
selects the shutdown mode (Default D0 = 0).
Table V. Configuration Register
D7 D6 D5 D4 D3 D2 D1 D0
Channel Fault OTI Cmp/ Shut-
Selection Queue Polarity Int down
The AD7416 contains a temperature-only channel, the
AD7417 has four analog input channels and a temperature
channel, and the AD7418 has two channels, a temperature
channel, and an analog input channel. The temperature chan-
nel address for all parts is the same, CH0. The address for the
analog input channel on the AD7418 is CH4. Table VI outlines
the channel selection on the parts, while Table VII shows the
fault queue settings. D1 and D2 are explained in the OTI Out-
put section.
Table VI. Channel Selection
D7 D6 D5 Channel Selection
00 0Temperature Sensor (All Parts)
00 1 A
IN1
(AD7417 Only)
01 0 A
IN2
(AD7417 Only)
01 1 A
IN3
(AD7417 Only)
10 0 A
IN4
(AD7417) and A
IN
(AD7418)
Table VII. Fault Queue Settings
D4 D3 Number of Faults
00 1 (Power-Up Default)
01 2
10 4
11 6
T
HYST
SETPOINT REGISTER (ADDRESS 02h)
The T
HYST
Setpoint Register is a 16-bit, read/write register whose
nine MSBs store the T
HYST
setpoint in twos complement for-
mat equivalent to the nine MSBs of the Temperature Value
Register. Bits 6 to 0 are unused.
T
OTI
SETPOINT REGISTER (ADDRESS 03h)
The T
OTI
Setpoint Register is a 16-bit, read/write register
whose nine MSBs store the T
OTI
setpoint in twos complement
format equivalent to the nine MSBs of the Temperature Value
Register. Bits 6 to 0 are unused.
Table VIII. Setpoint Registers
D15 D14 D13 D12 D11 D10 D9 D8 D7
MSB B7 B6 B5 B4 B3 B2 B1 LSB
ADC VALUE REGISTER (ADDRESS 04h)
The ADC Value Register is a 16-bit, read-only register whose
10 MSBs store the value produced by the ADC in binary for-
mat. Bits 5 to 0 are unused. Table IX shows the ADC Value
Register with 10 MSBs containing the ADC conversion request.
Table IX. ADC Value Register
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6
MSB B8 B7 B6 B5 B4 B3 B2 B1 LSB
ADC Transfer Function
The designed code transitions occur at successive integer LSB
values (i.e., 1 LSB, 2 LSB, and so on). The LSB size = VREF/
1024. The ideal transfer function characteristic for the AD7417
and AD7418 ADC is shown in Figure 7.
111...111
111...110
111...000
011...111
000...010
000...001
000...000
ADC CODE
0V 1/2LSB +VREF – 1LSB
ANALOG INPUT
1LSB = V REF/1024
Figure 7. Ideal Transfer Function Characteristic
for the AD7417/AD7418
CONFIG2 REGISTER (ADDRESS 05h)
A second configuration register is included in the AD7417/
AD7418 for the functionality of the CONVST pin. It is an 8-bit
register with Bits D5 to D0 being left at 0. Bit D7 determines
whether the AD7417/AD7418 should be operated in its default
mode (D7 = 0), performing conversions every 355 µs or in its
CONVST pin mode (D7 = 1), where conversions will start only
when the CONVST pin is used. Bit 6 contains the Test 1 Bit.
When this bit is 0, the I
2
C filters are enabled (default). A 1
disables the filters.
Table X. CONFIG2 Register
D7 D6 D5 D4 D3 D2 D1 D0
Conversion Mode Test 1 0 0 0 0 0 0
SERIAL BUS INTERFACE
Control of the AD7416/AD7417/AD7418 is carried out via the
I
2
C compatible serial bus. The AD7416/AD7417/AD7418 is
connected to this bus as a slave device, under the control of a
master device, e.g., the processor.
SERIAL BUS ADDRESS
As with all I
2
C compatible devices, the AD7416/AD7417/AD7418
have a 7-bit serial address. The four MSBs of this address for the
AD7416 are set to 1001; the AD7417 are set to 0101, while the
three LSBs can be set by the user by connecting the A2 to A0
pins to either V
DD
or GND. By giving them different addresses, up
to eight AD7416/AD7417s can be connected to a single serial bus,
REV. G–12–
AD7416/AD7417/AD7418
or the addresses can be set to avoid conflicts with other devices
on the bus. The four MSBs of this address for the AD7418 are set
to 0101, while the three LSBs are all set to zero.
If a serial communication occurs during a conversion operation,
the conversion will stop and will restart after the communication.
The serial bus protocol operates as follows:
1. The master initiates data transfer by establishing a start
condition, defined as a high-to-low transition on the serial
data line, SDA, while the serial clock line, SCL, remains
high. This indicates that an address/data stream will follow.
All slave peripherals connected to the serial bus respond to
the 7-bit address (MSB first) plus an R/W bit, which deter-
mines the direction of the data transfer, i.e., whether data
will be written to or read from the slave device.
The peripheral whose address corresponds to the transmitted
address responds by pulling the data line low during the low
period before the ninth clock pulse, known as the Acknowl-
edge bit. All other devices on the bus now remain idle while
the selected device waits for data to be read from or written
to it. If the R/W bit is a 0, then the master will write to the
slave device. If the R/W bit is a 1, then the master will read
from the slave device.
2. Data is sent over the serial bus in sequences of nine clock
pulses, eight bits of data followed by an Acknowledge bit
from the receiver of data. Transitions on the data line must
occur during the low period of the clock signal and remain
stable during the high period, since a low-to-high transition
when the clock is high may be interpreted as a stop signal.
3. When all data bytes have been read or written, stop condi-
tions are established. In write mode, the master will pull the
data line high during the 10th clock pulse to assert a stop
condition. In read mode, the master device will pull the data
line high during the low period before the 9th clock pulse.
This is known as No Acknowledge. The master will then take
the data line low during the low period before the 10th clock
pulse, then high during the 10th clock pulse to assert a stop
condition.
Any number of bytes of data may be transferred over the serial
bus in one operation, but it is not possible to mix read and write
in one operation because the type of operation is determined at
the beginning and cannot subsequently be changed without
starting a new operation.
WRITING TO THE AD7416/AD7417/AD7418
Depending on the register being written to, there are three
different writes for the AD7416/AD7417/AD7418.
1. Writing to the Address Pointer Register for a subsequent read.
In order to read data from a particular register, the Address
Pointer Register must contain the address of that register. If
it does not, the correct address must be written to the Address
Pointer Register by performing a single-byte write operation,
as shown in Figure 8. The write operation consists of the
serial bus address followed by the address pointer byte. No
data is written to any of the data registers.
2. Writing a single byte of data to the configuration registers or
to the T
OTI
, T
HYST
registers.
The Configuration Register is an 8-bit register, so only one
byte of data can be written to it. If only 8-bit temperature
comparisons are required, the temperature LSB can be
ignored in T
OTI
and T
HYST
, and only eight bits need be
written to the T
OTI
and T
HYST
registers.
Writing a single byte of data to one of these registers consists
of the serial bus address, the data register address written to
R/W
1
SCL
SDA 00
1A2 A1 A0 P7 P6 P5 P4 P3 P2 P1 P0
ACK. BY
AD7416
STOP BY
MASTER
START BY
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
ADDRESS POINTER REGISTER BYTE
191
ACK. BY
AD7416
9
Figure 8. Writing to the Address Pointer Register to Select a Data Register for a Subsequent Read Operation
R/W
1
SCL
SDA 001A2 A1 A0 P7 P6 P5 P4 P3 P2 P1 P0
ACK. BY
AD7416
START BY
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
ADDRESS POINTER REGISTER BYTE
19
1
ACK. BY
AD7416
9
D7 D6 D5 D4 D3 D2 D1 D0
ACK. BY
AD7416
STOP BY
MASTER
FRAME 3
DATA BYTE
19
SCL (CONTINUED)
SDA (CONTINUED)
Figure 9. Writing to the Address Pointer Register Followed by a Single Byte of Data to the Selected Data Register
REV. G
AD7416/AD7417/AD7418
–13–
the Address Pointer Register, followed by the data byte writ-
ten to the selected data register. This is illustrated in Figure 9.
3. Writing two bytes of data to the T
OTI
or T
HYST
Register.
If 9-bit resolution is required for the temperature setpoints,
two bytes of data must be written to the T
OTI
and T
HYST
registers. This consists of the serial bus address, the register
address written to the address pointer register, followed by
two data bytes written to the selected data register. This is
illustrated in Figure 10.
READING DATA FROM THE AD7416/AD7417/AD7418
Reading data from the AD7416/AD7417/AD7418 is a one or
two byte operation. Reading back the contents of the Configura-
tion Register is a single byte read operation, as shown in Figure
11, the register address previously having been set by a single-
byte write operation to the Address Pointer Register.
Reading data from the temperature value, T
OTI
or T
HYST
Regis-
ter, is a two-byte operation, as shown in Figure 12. It is also
possible to read the most significant bit of a 9-bit/10-bit register
in this manner.
R/W
1
SCL
SDA 0 0 1A2 A1 A0 P7 P6 P5 P4 P3 P2 P1 P0
ACK. BY
AD7416
START BY
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
ADDRESS POINTER REGISTER BYTE
191
ACK. BY
AD7416
9
D15 D14 D13 D12 D11 D10 D9 D8
ACK. BY
AD7416
STOP BY
MASTER
FRAME 3
MOST SIGNIFICANT DATA BYTE
19
SCL
(CONTINUED)
SDA
(CONTINUED) D7 D6 D5 D4 D3 D2 D1 D0
ACK. BY
AD7416
STOP BY
MASTER
FRAME 4
LEAST SIGNIFICANT DATA BYTE
19
Figure 10. Writing to the Address Pointer Register Followed by Two Bytes of Data to the T
OTI
or T
HYST
Register
SDA
NO ACK. BY
MASTER
START BY
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
SINGLE DATA BYTE FROM AD7416
ACK. BY
AD7416
191 9
D7 D6 D5 D4 D3 D2 D1 D0
R/W
A0A1A2101
SCL
STOP BY
MASTER
0
Figure 11. Reading a Single Byte of Data from the Configuration Register
R/W
1
SCL
SDA 001A2A1A0 D15 D14 D13 D12 D11 D10 D9 D8
ACK. BY
MASTER
START BY
MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
MOST SIGNIFICANT DATA BYTE FROM AD7416
19
1
ACK. BY
AD7416
9
D7 D6 D5 D4 D3 D2 D1 D0
NO ACK. BY
MASTER
STOP BY
MASTER
FRAME 3
LEAST SIGNIFICANT DATA BYTE FROM AD7416
19
SCL (CONTINUED)
SDA (CONTINUED)
Figure 12. Reading Two Bytes of Data from the T
OTI
or T
HYST
Register
REV. G–14–
AD7416/AD7417/AD7418
Please note that when reading back from the ADT7416/
ADT7417/ADT7418, no more than three bytes of data must be
read back. A STOP command must be inserted at the end of
the read communication. If a STOP command is not inserted
by the master and the ADT7416/ADT7417/ADT7418 receives
more SCL cycles than the maximum needed for three bytes of
data, then the I
2
C interface on the ADT7416/ADT7417/
ADT7418 will pull the SDA line low and prevent it from going
high again. To recover the ADT7416/ADT7417/ADT7418
interface the part must be powered off and on again. Reference
the application note, AN-686, on the Analog Devices website
for more information on I
2
C interfaces.
OTI OUTPUT
The OTI output has two operating modes, which are selected
by Bit D1 of the Configuration Register. In the comparator
mode, (D1 = 0), the OTI output becomes active when the
temperature exceeds T
OTI
and remains active until the tempera-
ture falls below T
HYST
. This mode allows the AD7416/AD7417/
AD7418 to be used as a thermostat, for example, to control the
operation of a cooling fan.
TOTI
THYST
OTI OUTPUT
COMPARATOR
MODE
OTI OUTPUT
INTERRUPT
MODE
READ*READ*READ*READ*READ*READ*READ*
IN INTERRUPT MODE, A READ OPERATION OR SHUTDOWN RESETS THE OTI
OUTPUT; OTHERWISE THE OTI OUTPUT REMAINS ACTIVE INDEFINITELY, ONCE
TRIGGERED.
*
Figure 13. Operation of OTI Output (Shown Active Low)
The open-drain configuration of OTI allows the OTI outputs of
several AD7416/AD7417/AD7418s to be wire-ANDed together
when in active low mode.
The OTI output is used to indicate that an out-of-limit tem-
perature excursion has occurred. OTI is an open-drain output
that can be programmed to be active low by setting Bit D2 of
the Configuration Register to 0 or active high by setting Bit D2
of the Configuration Register to 1.
In the interrupt mode (D1 = 1), the OTI output becomes active
when the temperature exceeds T
OTI
and remains active even if
the temperature falls below T
HYST
, until it is reset by a read opera-
tion. Once OTI has become active by the temperature exceeding
T
OTI
, and has then been reset, it will remain inactive even if the
temperature remains, or subsequently rises again, above T
OTI
. It
will not become active again until the temperature falls below
T
HYST
. It will then remain active until reset by a read opera-
tion. Once OTI has become active by the temperature falling
below T
HYST
and then reset, it will remain inactive even if the
temperature remains, or subsequently falls again, below T
HYST
.
OTI is also reset when the AD7416/AD7417/AD7418 is placed
in shutdown mode by setting Bit D0 of the Configuration Regis-
ter to 1.
The OTI output requires an external pull-up resistor. This can
be connected to a voltage different from V
DD
(for example, to
allow interfacing between 5 V and 3.3 V systems) provided that
the maximum voltage rating of the OTI output is not exceeded.
The value of the pull-up resistor depends on the application but
should be as large as possible to avoid excessive sink currents at
the OTI output, which can heat the chip and affect the tempera-
ture reading. The maximum value of the pull-up resistor that
will meet the output high current specification of the OTI out-
put is 30 kΩ, but higher values may be used if a lower output
current is required. For most applications, a value of 10 kΩ will
prove suitable.
FAULT QUEUE
To avoid false triggering of the AD7416/AD7417/AD7418 in
noisy environments, a fault queue counter is provided that can
be programmed by Bits D3 and D4 of the Configuration Regis-
ter (see Table V) to count 1, 2, 4, or 6 fault events before OTI
becomes active. In order to trigger OTI, the faults must occur
consecutively. For example, if the fault queue is set to 4, then
four consecutive temperature measurements greater than T
OTI
(or less than T
HYST
) must occur. Any reading that breaks the
sequence will reset the fault queue counter, so if there are three
readings greater than T
OTI
followed by a reading less than T
OTI
,
the fault queue counter will be reset without triggering OTI.
POWER-ON DEFAULTS
The AD7416/AD7417/AD7418 always powers up with the
following defaults.
Address pointer pointing to Temperature Value Register com-
parator mode
T
OTI
= 80°C
T
HYST
= 75°C
OTI Active LOW
Fault Queue = 1
These default settings allow the AD7416/AD7417/AD7418 to
be used as a standalone thermostat without any connection to a
serial bus.
OPERATING MODES
The AD7416/AD7417/AD7418 has two possible modes of
operation depending on the value of D0 in the Configuration
Register.
Mode 1
Normal operation of the AD7416/AD7417/AD7418 occurs when
D0 = 0. In this active mode, a conversion takes place every
400 µs. Once the conversion has taken place, the part partially
powers down, consuming typically 350 µA of the current until
the next conversion occurs.
Two situations can arise in this mode on the request of a tempera-
ture read. If a read occurs during a conversion, the conversion
aborts and a new one starts on the stop/repeat start condition.
The temperature value that is read is that of the previous com-
pleted conversion. The next conversion will typically occur
400 µs after the new conversion has begun.
If a read is called between conversions, a conversion is initiated
on the stop/repeat start condition. After this conversion, the part
returns to performing a conversion every 400 µs.
REV. G
AD7416/AD7417/AD7418
–15–
With a V
DD
= 3 V, for each 400 µs cycle, the AD7416 spends
40 µs (or 10% of the time) in conversion mode. It spends 360 µs
(or 90% of time) in partial power-down mode. Thus, the aver-
age power dissipated by the AD7416/AD7417/AD7418 is
301109 12mW ×+ ×=...mW mW
Mode 2
For applications where temperature measurements are required at
a slower rate, e.g., every second, power consumption of the part
can be reduced by writing to the part to go to a full power-down
between reads. The current consumption in full power-down is
typically 0.2 µA and full power-down is initiated when D0 = 1
in the Configuration Register. When a measurement is required,
a write operation can be performed to power-up the part. The
part then performs a conversion and is returned to power-down.
The temperature value can be read in the full power-down
because the I
2
C bus is continuously active.
The power dissipation in this mode depends on the rate at which
reads take place. Taking the requirements for a temperature
measurement every 100 ms as an example, the optimum power
dissipation is achieved by placing the part in full power-down,
waking it up every 100 ms, letting it operate for 400 µs and
putting it into full power-down again. In this case, the average
power consumption is calculated as follows. The part spends
40 µs (or 0.04% of time) converting with 3 mW dissipation and
a 99.96 ms (99.96% of time) in full shutdown with 60 nW dissipa-
tion. Thus, the average power dissipation is
30004 60 0 9996 1 2mW nW W×+ × =...µ
The fastest throughput rate at which the AD7416/AD7417/
AD7418 can be operated is 2.5 kHz (i.e., a read every 400 µs
conversion period). Since T
OTI
and T
HYST
are 2-byte reads, the
read time with the I
2
C operating at 100 kbit/s would be 270 µs.
If temperature reads are called too often, reads will overlap
with conversions, aborting them continuously, which results in
invalid readings.
CONVERT START MODE
The AD7417/AD7418 has an extra mode, set by writing to the
MSB of the Config2 Register.
CONVST Pin Mode
By setting the CONVST Mode Bit to 1, conversions are initiated
only by using the CONVST pin. In this method of operation,
CONVST is normally low.
The rising edge of CONVST starts the power-up time. This
power-up time is 4 µs. If the CONVST high time is longer than
4 µs, a conversion is initiated on the falling edge of CONVST
and the track-and-hold also enters its hold mode at this time. If
the CONVST high time is less than 4 µs, an internal timer,
initiated by the rising edge of CONVST holds off the track-and-
hold and the initiation of conversion until the timer times out
(4 µs after the rising edge of CONVST, which corresponds with
the power-up time). CONVST input remains low at the end of
conversion, thus causing the part to enter its power-down mode.
In this method of operation, CONVST is normally low with a
high going pulse controlling the power-up and conversion starts.
The CONVST pin should not be pulsed when reading from or
writing to the port.
Figure 17 shows the recommended minimum times for the
CONVST pulse when the temperature channel is selected.
Figure 18 shows the minimum times an analog input channel
is selected.
APPLICATIONS INFORMATION
SUPPLY DECOUPLING
The AD7416/AD7417/AD7418 should be decoupled with a
0.1 µF ceramic capacitor between V
DD
and GND. This is
particularly important if the part is mounted remote from the
power supply.
POWER-ON-RESET
To ensure proper power-on-reset, make sure that the supply
voltage on the V
DD
pin is at 0 V. Refer to application note
AN-588 for more information. A failed power-on-reset can
prevent the default values from being loaded into the AD7416/
AD7417/AD7418 registers. If the correct values are not loaded
into the registers, then the device will not start operating. The
output from the value registers will be a constant value.
To get the device operating again, the registers will have to be
loaded with their default values via the I
2
C bus. Therefore, in
the event of an inadequate power-on-reset and for all three
devices, the following registers should be loaded with their
default values:
Configuration Register 1—Default Value = 00h
Configuration Register 2—Default Value = 00h
T
HYST
Setpoint Register—Default Value = 4B00h
T
OTI
Setpoint Register—Default Value = 5500h
MOUNTING THE AD7416
The AD7416/AD7417/AD7418 can be used for surface or air
temperature sensing applications. If the device is cemented to a
surface with thermally conductive adhesive, the die temperature
will be within about 0.2°C of the surface temperature, thanks to
the device’s low power consumption. Care should be taken to
insulate the back and leads of the device from the air, if the
ambient air temperature is different from the surface tempera-
ture being measured.
The ground pin provides the best thermal path to the die, so the
temperature of the die will be close to that of the printed circuit
ground track. Care should be taken to ensure that this is in good
thermal contact with the surface being measured.
As with any IC, the AD7416/AD7417/AD7418 and its associ-
ated wiring and circuits must be kept free from moisture to
prevent leakage and corrosion, particularly in cold conditions
where condensation is more likely to occur. Water resistant
varnishes and conformal coatings can be used for protection.
The small size of the AD7416 package allows it to be mounted
inside sealed metal probes that provide a safe environment for
the device.
REV. G–16–
AD7416/AD7417/AD7418
FAN CONTROLLER
Figure 14 shows a simple fan controller that will switch ON a
cooling fan when the temperature exceeds 80°C and switch it
OFF again when the temperature falls below 75°C. The AD7416
can be used standalone in this application or with a serial bus
interface if different trip temperatures are required. If the AD7416
is used with a bus interface, the sense of OTI can be set to active
high, Q1 and R1 can be omitted, and OTI can be connected
directly to the gate of Q2 with R2 as the pull-up resistor.
V
DD
3V TO 5.5V
AD7416
R1
10k⍀
Q1
2N3904
OR SIMILAR
R2
10k⍀
Q2
LOGIC LEVEL
MOSFET RATED
TO SUIT FAN
CURRENT
12V
Figure 14. AD7416 Used as a Fan Controller
THERMOSTAT
Figure 15 shows the AD7416 used as a thermostat. The heater
will be switched ON when the temperature falls below T
HYST
and switched OFF again when the temperature rises above
T
OTI
. For this application and for comparator mode, the OTI
output should be programmed active low.
V
DD
3V TO
5.5V
AD7416
R1
10k⍀
Q1
2N3904
OR SIMILAR
RELAY D1
1N4001
HEATER
HEATER
SUPPLY
RLA1
Figure 15. AD7416 Used as a Thermostat
SYSTEM WITH MULTIPLE AD7416S
The three LSBs of the AD7416’s serial address can be set by the
user, allowing eight different addresses from 1001000 to 1001111.
Figure 16 shows a system in which eight AD7416s are connected
to a single serial bus, with their OTI outputs wire-ANDed
together to form a common interrupt line. This arrangement
does mean that each device must be read to determine which
one has generated the interrupt, and if a unique interrupt is
required for each device, the OTI outputs can be connected
separately to the I/O chip.
PROCESSOR
AD7416
SUPER I/O CHIP
AD7416
AD7416
AD7416
AD7416
AD7416
AD7416
AD7416
VDD
3V TO 5.5V
R1
10k⍀
Figure 16. Multiple Connection of AD7416s to a Single Serial Bus
100ns
40␮s
CONVST
Figure 17.
CONVST
When Temperature Channel Selected
100ns
15␮s
C
ONVST
Figure 18.
CONVST
When V
IN
Channel(s) Selected
REV. G
AD7416/AD7417/AD7418
–17–
OUTLINE DIMENSIONS
Purchase of licensed I
2
C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips I
2
C
Patent Rights to use these components in an I
2
C system, provided that the system conforms to the I
2
C Standard Specification as defined by Philips.
16-Lead Standard Small Outline Package [SOIC]
Narrow Body
(R-16)
Dimensions shown in millimeters and (inches)
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COMPLIANT TO JEDEC STANDARDS MS-012AC
16 9
8
1
4.00 (0.1575)
3.80 (0.1496)
10.00 (0.3937)
9.80 (0.3858)
1.27 (0.0500)
BSC
6.20 (0.2441)
5.80 (0.2283)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0039)
0.51 (0.0201)
0.31 (0.0122)
1.75 (0.0689)
1.35 (0.0531)
8ⴗ
0ⴗ
0.50 (0.0197)
0.25 (0.0098)
1.27 (0.0500)
0.40 (0.0157)
COPLANARITY
0.10
ⴛ 45ⴗ
0.25 (0.0098)
0.17 (0.0067)
16-Lead Thin Shrink Small Outline Package [TSSOP]
(RU-16)
Dimensions shown in millimeters
16 9
81
PIN 1
SEATING
PLANE
8ⴗ
0ⴗ
4.50
4.40
4.30
6.40
BSC
5.10
5.00
4.90
0.65
BSC
0.15
0.05
1.20
MAX
0.20
0.09 0.75
0.60
0.45
0.30
0.19
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-153AB
8-Lead Standard Small Outline Package [SOIC]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
0.50 (0.0196)
0.25 (0.0099) ⴛ 45ⴗ
8ⴗ
0ⴗ
1.75 (0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
85
41
5.00 (0.1968)
4.80 (0.1890)
4.00 (0.1574)
3.80 (0.1497)
1.27 (0.0500)
BSC
6.20 (0.2440)
5.80 (0.2284)
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COMPLIANT TO JEDEC STANDARDS MS-012AA
8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
0.80
0.60
0.40
8ⴗ
0ⴗ
85
4
1
4.90
BSC
PIN 1
0.65 BSC
3.00
BSC
SEATING
PLANE
0.15
0.00
0.38
0.22
1.10 MAX
3.00
BSC
COPLANARITY
0.10
0.23
0.08
COMPLIANT TO JEDEC STANDARDS MO-187AA
REV. G–18–
AD7416/AD7417/AD7418
Revision History
Location Page
8/04—Data Sheet Changed from REV. F to REV. G.
Changes to Figure 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Changes to READING DATA FROM THE AD7416/AD7417/AD7418 section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Changes to POWER-ON-RESET section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7/03–Data Sheet Changed from REV. E to REV. F.
Updated FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Updated SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Updated ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Updated ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Updated PRODUCT HIGHLIGHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Updated CIRCUIT INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Updated TEMPERATURE MEASUREMENT section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
10/02–Data Sheet Changed from REV. D to REV. E.
Edits to SPECIFICATIONS headings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Added TEMPERATURE MEASUREMENT section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Edits to SERIAL BUS ADDRESS section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Edits to Figure 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Edits to CONVST Pin Mode section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Edits to POWER-ON-RESET section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Addition of Figures 16 and 17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Updated OUTLINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
–19–
C01126–0–8/04(G)
–20–