Datasheet AD7417 Datasheet (ANALOG DEVICES)

10-Bit Digital Temperature Sensor

V

V

(AD7416) and Four Single-Channel ADCs

FEATURES

10-bit ADC with 15 μs and 30 μs conversion times
Single and 4 single-ended analog input channels
On-chip temperature sensor: −40°C to +125°C
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

2

I

C-compatible serial interface

Selectable serial bus address allows connection of up to 8

AD7416/AD7417 devices 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

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 oscillator, 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 multip­lexer 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 tempera­ture limits, and an open-drain overtemperature indicator (OTI)
output is provided, which becomes active when a programmed
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.

AD7416/AD7417/AD7418

FUNCTIONAL BLOCK DIAGRAMS

BAND GAP

TEMPERATURE

SENSOR

ADDRESS

POINTER

REGISTER

7

A0

6

A1

A2

5

TEMP

SENSOR

7

A

IN1

8

A

IN2

A

IN3

A

IN4

NC = NO CONNECT

A

MUX

9

10

1

16NC6

NC

DD

7

TEMP

SENSOR

5

MUX

IN

ANALOG-TO-DIGITAL

CONVERTER

TEMPERATURE

T

OTI

T

HYST

CONFIGURATION

Figure 1. AD7416

REF

IN

5

REF

2.5V

SAMPLING

CAPACITOR

V

BALANCE

GND

Figure 2. AD7417

REF

IN

6

REF

2.5V

SAMPLING

CAPACITOR

V

BALANCE

4

GND

Figure 3. AD7418

10-BIT

VAL UE

REGISTER

SETPOINT

REGISTER

SETPOINT

REGISTER

REGISTER

SERIAL BUS

INTERFACE

T

SETPOINT

OTI

REGIS TER

CHARGE

DISTRIBUTI ON

DAC

CLOCK

15

CONVST

T

SETPOINT

OTI

REGIS TER

CHARGE

DISTRIBUTI ON

DAC

CONTROL

CLOCK

8

CONVST

DD

14

CONTROL

LOGIC

LOGIC

AD7416

SETPOINT

COMPARATOR

FAULT

QUEUE

COUNTER

A > B

B

A

DATA OUT

2

I

C

INTERFACE

AD7417

13

12 11

A0

A1 A2

A > B

B

A

DATA OUT

2

I

C

INTERFACE

AD7418

8

V

DD

3

OTI

4

GND

SDA

1

2

SCL

01126-001

4

OTI

3

SCL

SDA

2

01126-002

3

OTI

2

SCL

SDA

1

01126-003

Rev. I

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. No
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Tel: [phone] www.analog.com
Fax: [phone] ©1998–2010 Analog Devices, Inc. All rights reserved.

AD7416/AD7417/AD7418

TABLE OF CONTENTS

Features.............................................................................................. 1

Applications....................................................................................... 1

General Description ......................................................................... 1

Functional Block Diagrams............................................................. 1

Revision History ............................................................................... 2

Product Highlights ........................................................................... 3

Specifications..................................................................................... 4

AD7417/AD7418 Specifications................................................. 4

AD7416 Specifications................................................................. 6

Absolute Maximum Ratings............................................................ 7

ESD Caution.................................................................................. 7

Pin Configurations and Function Descriptions ........................... 8

Terminology .................................................................................... 10

Theory of Operation ...................................................................... 11

Circuit Information.................................................................... 11

Converter Details........................................................................ 11

Typical Connection Diagram ................................................... 11

Analog Inputs.............................................................................. 11

REVISION HISTORY

11/10—Rev. H to Rev. I

Changes to Figure 19...................................................................... 16

2/09—Rev. G to Rev. H

Updated Format..................................................................Universal

Changes to Data Sheet Title, Figure 2 and Figure 3..................... 1

Moved Product Highlights Section................................................ 3

Changes to Table 1............................................................................ 4

Changes to Endnote 1, Table 2........................................................ 6

Added Figure 5 Caption................................................................... 7

Changes to Table 4............................................................................ 8

Changes to Table 5 and Table 6....................................................... 9

Changes to On-Chip Reference Section...................................... 11

Changes to Figure 13...................................................................... 12

Changes to Table 8 and Table 10................................................... 13

Changes to Figure 15, Figure 16, and Figure 17 ......................... 15

Changes to Reading Data From the AD7416/AD7417/AD7418

Section, Figure 18, and Figure 19 ................................................. 16

Change to Mode 1 .......................................................................... 17

Changes to Figure 22 Caption and

Section.............................................................................................. 18

Moved Figure 21 and Figure 22 .................................................... 18

Changes to Power-On Reset Section............................................ 19

Updated Outline Dimensions....................................................... 21

Changes to Ordering Guide.......................................................... 23

CONVST

Pin Mode

On-Chip Reference .................................................................... 11

Temperature Measurement....................................................... 12

Internal Register Structure........................................................ 12

Serial Bus Interface..................................................................... 14

OTI Output ................................................................................. 17

Fault Queue................................................................................. 17

Power-On Defaults..................................................................... 17

Operating Modes........................................................................ 17

CONVST

Applications Information.............................................................. 19

Supply Decoupling..................................................................... 19

Power-On Reset.......................................................................... 19

Mounting the AD7416/AD7417/AD7418 .............................. 19

Fan Controller............................................................................. 19

Thermostat.................................................................................. 19

System with Multiple AD7416 Devices................................... 20

Outline Dimensions....................................................................... 21

Ordering Guide .......................................................................... 23

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

Edits to Power-On-Reset section ................................................. 14

Addition of Figures 16 and 17 ...................................................... 15

Updated Outlines ........................................................................... 16

Start Mode................................................................. 18

CONVST

Pin Mode section ........................................... 14

Rev. I | Page 2 of 24

AD7416/AD7417/AD7418

An I2C® compatible serial interface allows the AD7416/AD7417/
AD7418 registers to be written to and read back. The three
LSBs of the AD7416/AD7417 serial bus address can be selected,
which allows up to eight AD7416/AD7417 devices to be connected
to a single bus.

The AD7417 is available in a narrow body, 0.15 inch, 16-lead,
small outline package (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 T

2. The AD7417 offers a space-saving, 10-bit analog-to-digital

solution with four external voltage input channels, an on­chip temperature sensor, an on-chip reference, and a 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.

setpoint register.

OTI

Rev. I | Page 3 of 24

AD7416/AD7417/AD7418

SPECIFICATIONS

AD7417/AD7418 SPECIFICATIONS

VDD = 2.7 V to 5.5 V, GND = 0 V, REFIN = 2.5 V, unless otherwise noted.

Table 1.

Parameter A Version B Version1 Unit Test Conditions/Comments

DC ACCURACY Any channel

Resolution 10 10 Bits
Minimum Resolution for Which No

Missing Codes Are Guaranteed
Relative Accuracy2 ±1 ±1 LSB max This specification is typical for VDD of 3.6 V to 5.5 V
Differential Nonlinearity2 ±1 ±1 LSB max This specification is typical for VDD of 3.6 V to 5.5 V
Gain Error2 ±3 ±3 LSB max External reference
±10 ±10 LSB max Internal reference
Gain Error Match2 ±0.6 ±0.6 LSB max AD7417 only
Offset Error2 ±4 ±4 LSB max
Offset Error Match2 ±0.7 ±0.7 LSB max AD7417 only

ANALOG INPUTS

Input Voltage Range VREF VREF V max
0 0 V min
Input Leakage Current3 ±1 ±1 A max
Input Capacitance 10 10 pF max

TEMPERATURE SENSOR1

Measurement Error

Ambient Temperature 25°C ±2 ±1 °C max
T

to T

MIN

Temperature Resolution 1/4 1/4 °C/LSB

CONVERSION RATE

Track-and-Hold Acquisition Time4 400 400 ns max Source impedance < 10 Ω
Conversion Time

Temperature Sensor 30 30 s max Typically 27 s

Channel 1 to Channel 4 15 15 s max Typically 10 s

REFERENCE INPUT

REFIN Input Voltage Range 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 Error6 ±25 ±25 mV max
Temperature Coefficient6 80 80 ppm/°C typ

DIGITAL INPUTS

Input High Voltage, VIH VDD × 0.7 VDD × 0.7 V min
Input Low Voltage, VIL VDD × 0.3 VDD × 0.3 V max
Input Leakage Current 1 1 A max

DIGITAL OUTPUTS

Output Low Voltage, VOL 0.4 0.4 V max IOL = 3 mA
Output High Current 1 1 A max VOH = 5 V

±3 ±2 °C max

MAX

5, 6

10 10 Bits

Rev. I | Page 4 of 24

AD7416/AD7417/AD7418

Parameter A Version B Version1 Unit Test Conditions/Comments

POWER REQUIREMENTS

VDD 5.5 5.5 V max For specified performance

2.7 2.7 V min
IDD Logic inputs = 0 V or VDD

Normal Operation 600 600 A max
Power-Down 1.5 1.5 A max 0.7 µA typically

Auto Power-Down Mode VDD = 3 V; see the Operating Modes section

10 SPS Throughput Rate 6 6 W typ
1 kSPS Throughput Rate 60 60 W typ
10 kSPS Throughput Rate 600 600 W typ

Power-Down 3 3 W max Typically 0.15 W

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 VDD = 2.7 V, TA = 85°C maximum and

temperature sensor measurement error = ±3°C maximum.

2

See the Terminology section.

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 an external reference is applied.

6

The accuracy of the temperature sensor is affected by reference tolerance.

Rev. I | Page 5 of 24

AD7416/AD7417/AD7418

AD7416 SPECIFICATIONS

VDD = 2.7 V to 5.5 V, GND = 0 V, REFIN = 2.5 V, unless otherwise noted.

Table 2.

Parameter Min Typ Max Unit Test Conditions/Comments

TEMPERATURE SENSOR AND ADC

Accuracy ±2.0 °C TA = −25°C to + 100°C
(V
±3.0 °C TA = −40°C to + 125°C
(V
Resolution 10 Bits
Temperature Conversion Time 40 s
Update Rate, tR 400 s
OTI Delay 1 × tR 6 × tR ms Depends on fault queue setting
Supply Current 1.0 mA I2C active
350 600 A I2C inactive

0.2 1.5 A Shutdown mode
T

Default Temperature 80 °C

OTI

T

Default Temperature 75 °C

HYST

DIGITAL INPUTS

Input High Voltage, VIH VDD × 0.7 VDD + 0.5 V
Input Low Voltage, VIL −0.3 VDD × 0.3 V
Input High Current, IIH +0.005 +1.0 A VIN = 5 V
Input Low Current, IIL −0.005 −1.0 A VIN = 0 V
Input Capacitance, CIN 20 pF All digital inputs

DIGITAL OUTPUTS

Output Low Voltage, VOL 0.4 V IOL = 3 mA
Output High Current 1 A VOH = 5 V
Output Fall Time, tf 250 ns CL = 400 pF, IO = 3 mA
OS Output Low Voltage, VOL 0.8 V I

AC ELECTRICAL CHARACTERISTICS2 AD7416/AD7417/AD7418

Serial Clock Period, t1 2.5 s See Figure 4
Data In Setup Time to SCL High, t2 50 ns See Figure 4
Data Out Stable after SCL Low, t3 0 ns See Figure 4
SDA Low Setup Time to SCL Low

(Start Condition), t4 50 ns See Figure 4

SDA High Hold Time after SCL High

(Stop Condition), t5 50 ns See Figure 4

SDA and SCL Fall Time, t6 300 ns See Figure 4

1

For VDD = 2.7 V to 3 V, TA maximum = 85°C and temperature sensor measurement error = ±3°C maximum.

2

Sample tested during initial release and after any redesign or process change that may affect this parameter.

t

1

SCL

= 3 V minimum)1

DD

= 3 V minimum)1

DD

= 4 mA

OUT

SDA

DATA IN

SDA

DATA OUT

t

4

t

2

t

3

t

5

t

6

01126-004

Figure 4. Diagram for Serial Bus Timing

Rev. I | Page 6 of 24

AD7416/AD7417/AD7418

V

ABSOLUTE MAXIMUM RATINGS

TA = 25°C, unless otherwise noted.

Table 3.

Parameter Rating

VDD to AGND −0.3 V to +7 V
VDD to DGND −0.3 V to +7 V
Analog Input Voltage to AGND

A

to A

IN1

−0.3 V to VDD + 0.3 V

IN4

Reference Input Voltage to AGND1 −0.3 V to VDD + 0.3 V
Digital Input Voltage to DGND −0.3 V to VDD + 0.3 V
Digital Output Voltage to DGND −0.3 V to VDD + 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

θJA 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

θJA 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

θJA 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

θJA Thermal Impedance 206°C/W
Lead Temperature, Soldering

Vapor Phase (60 sec) 215°C
Infrared (15 sec) 220°C

1

If the reference input voltage is likely to exceed VDD by more than 0.3 V (for

example, during power-up) and the reference is capable of supplying 30 mA
or more, it is recommended to use a clamping diode between the REFIN pin
and the V

pin. Figure 5 shows how the diode should be connected.

DD

Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.

REF

IN

AD7417

Figure 5. Diode Connection

BAT81

DD

01126-025

ESD CAUTION

Rev. I | Page 7 of 24

AD7416/AD7417/AD7418

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

NC

1

SDA

2

SCL

3

AD7417

4

OTI

TOP VIEW

5

IN

GND

6

A

7

IN1

8

A

IN2

NC = NO CONNECT

(Not to Scale)

REF

Figure 6. AD7417 Pin Configuration (SOIC/TSSOP)

Table 4. AD7417 Pin Function Descriptions

Pin No. Mnemonic Description

1, 16 NC No Connection. Do not connect anything to this pin.
2 SDA Digital I/O. Serial bus bidirectional data. Push-pull output.
3 SCL Digital Input. Serial bus clock.
4 OTI

This pin 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 T
serial read operation. Open-drain output.

5 REFIN

Reference Input. An external 2.5 V reference can be connected to the AD7417 at this pin. To enable the on-chip
reference, the REF

pin should be tied to GND. If an external reference is connected to the AD7417, the internal

IN

reference shuts down.
6 GND Ground reference for track-and-hold, comparator and capacitor DAC, and digital circuitry.
7 to 10 A

IN1

to A

Analog Input Channels. The AD7417 has four analog input channels. The input channels are single-ended with

IN4

respect to GND. The input channels can convert voltage signals in the range of 0 V to VREF. A channel is selected by

writing to the configuration register of the AD7417.
11 A2 Digital Input. This is the highest programmable bit of the serial bus address.
12 A1 Digital Input. This is the middle programmable bit of the serial bus address.
13 A0 Digital Input. This is the lowest programmable bit of the serial bus address.
14 VDD 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 s. If the CONVST pulse is greater than 4 s, 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 s, 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 the section). Operating Modes

16

15

14

13

12

11

10

9

NC

CONVST

V

DD

A0

A1

A2

A

IN4

A

IN3

01126-005

setpoint register. The signal is reset at the end of a

OTI

Rev. I | Page 8 of 24

AD7416/AD7417/AD7418

SDA

1

OTI

AD7416

2

3

TOP VIEW

(Not to Scal e)

4

SCL

GND

Figure 7. AD7416 Pin Configuration (SOIC/MSOP) Figure 8. AD7418 Pin Configuration (SOIC/MSOP)

Table 5. AD7416 Pin Function Descriptions

Pin No. Mnemonic Description

1 SDA Digital I/O. Serial bus bidirectional data. Push-pull output.
2 SCL Digital Input. Serial bus clock.
3 OTI

This pin is a logic output. The OTI is set if the result of a conversion on Channel 0 (temperature sensor) is greater
than an 8-bit word in the T

output.
4 GND Ground reference for track-and-hold, comparator and capacitor DAC, and digital circuitry.
5 A2 Digital Input. This is the highest programmable bit of the serial bus address.
6 A1 Digital Input. This is the middle programmable bit of the serial bus address.
7 A0 Digital Input. This is the lowest programmable bit of the serial bus address.
8 VDD Positive Supply Voltage, 2.7 V to 5.5 V.

Table 6. AD7418 Pin Function Descriptions

Pin No. Mnemonic Description

1 SDA Digital I/O. Serial bus bidirectional data. Push-pull output.
2 SCL Digital Input. Serial bus clock.
3 OTI

This is a logic output. The OTI is set if the result of a conversion on Channel 0 (temperature sensor) is greater than

an 8-bit word in the T

output.
4 GND Ground reference for track-and-hold, comparator and capacitor DAC, and digital circuitry.
5 AIN

Analog Input Channel. The input channel is single-ended with respect to GND. The input channel can convert

voltage signals in the range of 0 V to VREF. The analog input channel is selected by writing to the configuration

register of the AD7418 and choosing Channel 4.
6 REFIN

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

reference shuts down.
7 VDD Positive Supply Voltage, 2.7 V to 5.5 V.

CONVST

8

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 s. If the

mode into hold mode and initiates a conversion. If the pulse is less than 4 s, 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 the section). Operating Modes

V

8

DD

A0

7

6

A1

5

A2

1126 -0 06

setpoint register. The signal is reset at the end of a serial read operation. Open-drain

OTI

setpoint register. The signal is reset at the end of a serial read operation. Open-drain

OTI

pin should be tied to GND. If an external reference is connected to the AD7418, the internal

IN

CONVST

pulse is greater than 4 s, the falling edge of

SDA

SCL

OTI

GND

1

AD7418

2

3

TOP VIEW

(Not to Scale)

4

CONVST

CONVST

8

V

7

DD

6

REF

IN

5

A

IN

01126-007

places the track-and-hold

Rev. I | Page 9 of 24

AD7416/AD7417/AD7418

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, that is, 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, that is, 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 ±½ 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
means that the user must wait for the duration of the track-and­hold acquisition time after the end of conversion, or after a
channel change or step input change to A
another conversion, to ensure that the part operates to
specification.

input of the AD7417 or AD7418. It

IN

before starting

IN

Rev. I | Page 10 of 24

AD7416/AD7417/AD7418

V

A

THEORY OF OPERATION

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 that no external clock is required except when
reading from and writing to the serial port. The on-chip track­and-hold goes from track mode 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 mode 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.
Temperature measurement is explained in the Temperature
Measurement section.

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
minimum power consumption, the unused analog inputs
should be tied to GND.

TYPICAL CONNECTION DIAGRAM

Figure 9 shows a typical connection diagram for the AD7417.
Using the A0, A1, and A2 pins allows the user to select from up
to eight AD7417 devices on the same serial bus, if desired. An
external 2.5 V reference can be connected at the REF

pin. If an

IN

Rev. I | Page 11 of 24

external reference is used, a 10 μF capacitor should be connected
between REF

and GND. SDA and SCL form the 2-wire I2C

IN

compatible interface. For applications where power consump­tion is of concern, the automatic power-down at the end of a
conversion should be used to improve power performance (see
the Operating Modes section.)

SUPPLY

2.7V TO 5. 5V

0V TO 2.5V

OPTIONAL

EXTERNAL

REFERENCE

INPUT

AD780/
REF192

+ +

A

A

A

A

GND

0.1µF10µF

IN1

IN2

IN3

IN4

V

DD

AD7417

REF

INTERFACE

SCL
SDA

CONVST

OTI

A0
A1
A2

IN

10µF FOR
EXTERNAL
REFERENCE

2-WIRE

SERIAL

MICROCONTROLLER/

MICROPRO CESSOR

Figure 9. Typical AD7417 Connection Diagram

ANALOG INPUTS

Figure 10 shows an equivalent circuit of the analog input
structure 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 to prevent these
diodes from becoming 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. Capacitor C2 in Figure 10 is typically about 4 pF and
can primarily be attributed to pin capacitance. 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. Capacitor C1
is the ADC sampling capacitor and has a capacitance of 3 pF.

DD

D1

IN

4pF

C2

D2

R1

1kΩ

CONVERT PHASE: SWITCH OPEN
TRACK PHASE: SWI TCH CLOSED

Figure 10. Equivalent Analog Input Circuit

C1

3pF

V

BALANCE

01126-009

ON-CHIP REFERENCE

The AD7417/AD7418 have an on-chip 1.2 V band gap reference
that is amplified 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

pin to analog ground, which causes SW1 (see Figure 11) to

IN

open and the reference amplifier to power up during a conver­sion. Therefore, the on-chip reference is not available externally.

01126-008

AD7416/AD7417/AD7418

V

An external 2.5 V reference can be connected to the REFIN pin.
This has the effect of shutting down the on-chip reference
circuitry.

REF

1.2V

SW1

IN

26kΩ

24kΩ

1.2V

2.5V

EXTERNAL
REFERENCE
DETECT

BUFFER

Figure 11. 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. Unfortu­nately, this technique requires calibration to null out the effect
of the absolute value of V

The technique used in the AD7416/AD7417/AD7418 is to
measure the current change in V
at two different currents.

This is given by

BE

where:

K is Boltzmann’s constant.
q is the charge on the electron (1.6 × 10
T is the absolute temperature in Kelvins.
N is the ratio of the two currents.

IN × I

SENSING

TRANSISTOR

Figure 12. Temperature Measurement Technique

Figure 12 shows the method the AD7416/AD7417/AD7418 use
to measure the device temperature. To measure ΔV
sensor (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 ΔV
to give a temperature output in 10-bit twos complement form.

, which varies from device to device.

BE

when the device is operated

BE

()

NqKTV

n1/ ×=Δ

−19

Coulombs).

DD

SENSING
TRANSISTOR

BE

. This voltage is measured by the ADC

BE

, the

V

OUT+

TO ADC

V

OUT–

Rev. I | Page 12 of 24

1126-010

01126-011

The temperature resolution of the ADC is 0.25°C, which corres­ponds 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 (0x00) as a 16-bit word. The 10 MSBs
of this word store the temperature measurement (see Tabl e 9
and Tabl e 10 ).

The temperature conversion formulas using the 10 MSBs of the
temperature value register are

Positive Temperature = ADC Code/4 (1)

Negative Temperature = (ADC Code − 512)/4 (2)

The MSB is removed from ADC Code in Equation 2.

INTERNAL REGISTER STRUCTURE

The AD7417/AD7418 have seven internal registers, as shown in
Figure 13. 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).

TEMPERATURE

VAL UE

REGISTER

(READ-ONLY

ADDRESS 0x00)

CONFIGURATION

REGISTER

(READ/WRIT E

ADDRESS 0x01)

T

SETPOINT

HYST

ADDRESS POINT ER

REGISTER

(SELCTS DATA REGISTER

FOR READ /WRI TE)

ADDRESS

SERIAL BUS INTERFACE

Figure 13. AD7417/AD7418 Register Structure

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 the address pointer register are used to select a
data register.

Table 7. Address Pointer Register

P71 P61 P51 P41 P31 P2 P1 P0

0 0 0 0 0 Register select

1

P3 to P7 must be set to 0.

REGISTER

(READ/WRIT E

ADDRESS 0x02)

T

SETPOINT

OTI

REGISTER

(READ/WRIT E

ADDRESS 0x03)

ADC VALUE

REGISTER

(READ-ONLY

ADDRESS 0x04)

CONFIG2

REGISTER

(READ/WRIT E

ADDRESS 0x05)

DATA

SDA
SCL

01126-012

AD7416/AD7417/AD7418

Table 8. Register Addresses

P2 P1 P0 Registers

0 0 0 Temperature value
0 0 1 Configuration register
0 1 0 T
0 1 1 T

setpoint

HYST

setpoint

OTI

1 0 0 ADC value (AD7417/AD7418 only)
1 0 1 Config2 (AD7417/AD7418 only)

Temperature Value Register (Address 0x00)

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. Bit D5 to Bit D0 are unused.

Table 9. 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 Tabl e 10 . 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 10. Temperature Data Format

Temperature Digital Output

−128°C 10 0000 0000

−125°C 10 0000 1100

−100°C 10 0111 0000

−75°C 10 1101 0100

−50°C 11 0011 1000

−25°C 11 1001 1100

−10°C 11 1101 1000

−0.25°C 11 1111 1111
0°C 00 0000 0000
+0.25°C 00 0000 0001
+10°C 00 0010 1000
+25°C 00 0110 0100
+50°C 00 1100 1000
+75°C 01 0010 1100
+100°C 01 1001 0000
+125°C 01 1111 0100
+127°C 01 1111 1100

Configuration Register (Address 0x01)

The configuration register is an 8-bit, read/write register that is
used to set the operating modes of the AD7416/AD7417/AD7418.
Bit D7 to Bit D5 control the channel selection as outlined in
Tabl e 1 2 . Bits[D7:D5] should always be set to 000 for the AD7416.
Bit D4 and Bit 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 11. Configuration Register

D7 D6 D5 D4 D3 D2 D1 D0

Channel

selection

Fault

queue

OTI
polarity

Cmp/Int Shutdown

Rev. I | Page 13 of 24

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 channel address for all
parts is the same, Channel 0. The address for the analog input
channel on the AD7418 is Channel 4. Tabl e 12 outlines the
channel selection on the parts, and Ta b le 1 3 shows the fault
queue settings. D1 and D2 are explained in the OTI Output
section.

Table 12. Channel Selection

D7 D6 D5 Channel Selection

0 0 0 Temperature sensor (all parts), Channel 0
0 0 1 A
0 1 0 A
0 1 1 A
1 0 0 A

(AD7417 only), Channel 1

IN1

(AD7417 only), Channel 2

IN2

(AD7417 only), Channel 3

IN3

(AD7417) and AIN (AD7418), Channel 4

IN4

Table 13. Fault Queue Settings

D4 D3 Number of Faults

0 0 1 (power-up default)
0 1 2
1 0 4
1 1 6

T

Setpoint Register (Address 0x02)

HYST

The T
nine MSBs store the T

setpoint register is a 16-bit, read/write register whose

HYST

setpoint in twos complement format

HYST

equivalent to the nine MSBs of the temperature value register.
Bit D6 to Bit D0 are unused.

T

Setpoint Register (Address 0x03)

OTI

The T
nine MSBs store the T

setpoint register is a 16-bit, read/write register whose

OTI

setpoint in twos complement format

OTI

equivalent to the nine MSBs of the temperature value register.
Bit 6 to Bit 0 are unused.

Table 14. T

Setpoint and T

HYST

Setpoint Registers

OTI

D15 D14 D13 D12 D11 D10 D9 D8 D7

MSB B7 B6 B5 B4 B3 B2 B1 LSB

ADC Value Register (Address 0x04)

The ADC value register is a 16-bit, read-only register whose
10 MSBs store the value produced by the ADC in binary format.
Bit D5 to Bit D0 are unused. Tabl e 15 shows the ADC value
register with 10 MSBs containing the ADC conversion request.

Table 15. 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 (that is, 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 14.

AD7416/AD7417/AD7418

direction of the data transfer, that is, whether data is written

111.. .111

111.. .110

111...000

011...111

ADC CODE

000...010

000...001

000...000

0V 1/2LSB

Figure 14. Ideal Transfer Function Characteristic for the AD7417/AD7418

1LSB – VREF /1024

+VREF – 1LSB

ANALOG INPUT

01126-013

Config2 Register (Address 0x05)

A second configuration register is included in the AD7417/
AD7418 for the functionality of the

CONVST

pin. It is an 8-bit
register with Bit D5 to Bit 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

when the
When this bit is 0, the I

pin mode (D7 = 1), where conversions start only
CONVST

pin is used. Bit 6 contains the Test 1 bit.

2

C filters are enabled (default). Setting

this bit to 1 disables the filters.

Table 16. 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

2

C compatible serial bus. The AD7416/AD7417/AD7418 are

I
connected to this bus as a slave device, under the control of a
master device, for example, the processor.

Serial Bus Address

As with all I2C 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, and the
three LSBs can be set by the user by connecting the A2 to A0
pins to either V
up to eight AD7416/AD7417 devices can be connected to a
single serial bus, 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, and the three LSBs are all set to 0.

If a serial communication occurs during a conversion operation,
the conversion stops and restarts after the communication.

The serial bus protocol operates as follows:

1. The master initiates data transfer by establishing a start condi-

tion, 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 follows. All slave
peripherals connected to the serial bus respond to the 7-bit
address (MSB first) plus an R/

or GND. By giving them different addresses,

DD

W

bit, which determines the

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 acknowl­edge 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/

slave device. If the R/

W

bit is a 0, then the master writes to the

W

bit is a 1, then the master reads

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, because 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

conditions are established. In write mode, the master pulls
the data line high during the 10th clock pulse to assert a
stop condition. In read mode, the master device pulls the
data line high during the low period before the ninth clock
pulse. This is known as no acknowledge. The master then
takes 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 can 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.

• Writing to the address pointer register for a subsequent read.

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 15. 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.

• Writing a single byte of data to the configuration register, the

Config2 register, or to the T

setpoint or T

OTI

setpoint

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
written to the T

and T

OTI

setpoint and T

OTI

, and only eight bits need to be

HYST

setpoint registers.

HYST

Writing a single byte of data to one of these registers consists
of the serial bus address, the data register address written
to the address pointer register, followed by the data byte

Rev. I | Page 14 of 24

AD7416/AD7417/AD7418

S

written to the selected data register. This is illustrated in
Figure 16.

• Writing two bytes of data to the T

setpoint or T

OTI

setpoint register.
If 9-bit resolution is required for the temperature setpoints,
two bytes of data must be written to the T

setpoint and

OTI

1 19 9

SCL

HYST

setpoint registers. This consists of the serial bus

T

HYST

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 17.

DA 1001

START BY

MASTER

1

AD741x = AD7416/AD7417/AD7418.

Figure 15. Writing to the Address Pointer Register to Select a Data Register for a Subsequent Read Operation

1 1

SCL

SDA 1 0 0 1

START BY

MASTER

1

AD741x = AD7416/AD7417/AD7418.

Figure 16. Writing to the Address Pointer Register Followed by a Single Byte of Data to the Selected Data Register

A2 A1 P7 P6 P5 P4 P3 P2 P1 P0A0 R/ W

FRAME 1

SERIAL BUS ADDRESS BYTE

A2 A1 P7 P6 P5 P4 P3 P2 P1 P0

FRAME 1

SERIAL BUS ADDRESS BYTE

SCL (CONTINUED)

SDA (CONTINUED)

ACK. BY

AD741x

A0 R/ W

1

9

ACK. BY
AD741x

1

ADDRESS POINTE R REGISTER BYT E

1

D6D7 D5 D4 D3 D2 D1 D0

FRAME 2

FRAME 3

DATA BYTE

FRAME 2

ADDRESS POINTE R REGISTE R BYTE

ACK. BY
AD741x

9

ACK. BY
AD741x

9

ACK. BY
AD741x

MASTER

1

1

MASTER

STOP

BY

STOP

BY

1

01126-014

01126-015

119

SCL

SDA 1 0 0 1

START BY

MASTER

SERIAL BUS ADDRESS BYTE

SCL

(CONTINUED)

SDA

(CONTINUED)

1

AD741x = AD7416/AD7417/AD7418.

D15 D14 D13 D12 D 11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

Figure 17. Writing to the Address Pointer Register Followed by Two Bytes of Data to the T

A2

A1 P7 P6 P5 P4 P3 P2 P1 P0A0 R /W

FRAME 1

MOST SIG NIFICANT DATA BYTE

FRAME 3

ACK. BY
AD741x

ACK. BY
AD741x

1

ADDRESS POINT ER REGISTE R BYTE

119

STOP BY

1

MASTER

FRAME 2

LEAST SIGNIFICANT DATA BYTE

FRAME 4

Setpoint or T

OTI

HYST

9

ACK. BY

1

AD741x

9

ACK. BY
AD741x

Setpoint Register

1

STOP

BY

MASTER

01126-016

Rev. I | Page 15 of 24

AD7416/AD7417/AD7418

S

S

Reading Data From the AD7416/AD7417/AD7418

Reading data from the AD7416/AD7417/AD7418 is a single­byte or 2-byte operation. Reading back the contents of the
configuration register is a single-byte read operation, as shown
in Figure 18, with the register address previously having been
set by a single-byte write operation to the address pointer
register.

Reading data from the temperature value register, the T
setpoint or T

setpoint register is a 2-byte operation, as

HYST

OTI

shown in Figure 19. It is also possible to read the most
significant bit of a 9-bit or 10-bit register in this manner.

1 19 9

SCL

Note that when reading back from the AD7416/AD7417/
AD7418, 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 AD7416/AD7417/AD7418 receive more SCL
cycles than the maximum needed for three bytes of data, then

2

the I

C interface on the AD7416/AD7417/AD7418 pulls the
SDA line low and prevents it from going high again. To recover
the AD7416/AD7417/AD7418 interface, the part must be
powered off and on again. Reference the AN-686 Application
Note, Implementing an I
information on I

2

2

C® Reset at www.analog.com for more

C interfaces.

DA 1 0 0 1

START BY

MASTER

1

AD741x = AD7416/AD7417/AD7418.

SCL

DA 1001

START BY

MASTER

1

AD741x = AD7416/AD7417/AD7418.

A1 D7 D6 D5 D4 D3 D2 D1 D0A0A2 R /W

ACK. BY

1

AD741x

FRAME 1

SERIAL BUS ADDRESS BYTE

Figure 18. Reading a Single Byte of Data from the Configuration Register

1 1

A2 A1 D15 D14 D13 D12 D11 D10 D9 D8

FRAME 1

SERIAL BUS ADDRESS BYTE

SCL (CONTINUE D)

SDA (CONTINUED)

A0 R/W

9

ACK. BY
AD741x

1

1

Figure 19. Reading Two Bytes of Data from the T

SINGLE DATA BYTE FROM AD741x

MOST SI GNIFI CANT BYTE F ROM AD741x

D6D7 D5 D4 D3 D2 D1 D0

LEAST SIGNIFICANT DATA BYTE FROM AD741x

Setpoint or T

OTI

FRAME 2

FRAME 2

FRAME 3

Setpoint Register

HYST

1

NO ACK. BY

MASTER

1

NO ACK. BY

MASTER

ACK. BY

MASTER

1

9

STOP

MASTER

9

STOP

BY

MASTER

BY

01126-017

01126-018

Rev. I | Page 16 of 24

AD7416/AD7417/AD7418

OTI OUTPUT

The OTI output has two operating modes that 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
below T
be used as a thermostat, for example, to control the operation of
a cooling fan.

OTI OUTPUT

COMPARATOR

OTI OUTPUT

INTERRUPT

1

IN INTERRUPT MODE, A READ OPERATION OR SHUTDOWN RESETS THE OTI
OUTPUT; OTHERWISE, THE OTI OUTPUT REMAINSACTIVE INDEFINITELY,
ONCE TRIGG ERED.

The open-drain configuration of OTI allows the OTI outputs of
several AD7416/AD7417/AD7418 devices to be wire-AND’ed
together when in active low mode.

The OTI output is used to indicate that an out-of-limit tempera­ture 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
the temperature falls below T
tion. Once OTI becomes active by the temperature exceeding
T

, and resets, it remains inactive even if the temperature

OTI

remains, or subsequently rises again, above T
become active again until the temperature falls below T
then remains active until reset by a read operation. Once OTI
becomes active by the temperature falling below T
resets, it remains inactive even if the temperature remains, or
subsequently falls again, below T

OTI is also reset when the AD7416/AD7417/AD7418 are placed
in shutdown mode by setting Bit D0 of the configuration
register to 1.

The OTI output requires an external pull-up resistor. This can
be connected to a voltage different from V
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 temperature
reading. The maximum value of the pull-up resistor that meets
the output high current specification of the OTI output is 30 kΩ,
but higher values can be used if a lower output current is
required. For most applications, a value of 10 kΩ is suitable.

and remains active until the temperature falls

OTI

. This mode allows the AD7416/AD7417/AD7418 to

HYST

T

OTI

T

HYST

MODE

MODE

Figure 20. Operation of OTI Output (Shown Active Low)

1

READ

READ1READ1READ1READ1READ1READ

and remains active even if

OTI

, until it is reset by a read opera-

HYST

.

HYST

DD

. It does not

OTI

and then

HYST

(for example, to

1

. It

HYST

Rev. I | Page 17 of 24

01126-019

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 Bit D3 and Bit D4 of the configuration
register (see Ta b le 1 1) to count 1, 2, 4, or 6 fault events before
OTI becomes active. 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
(or less than T

) must occur. Any reading that breaks the

HYST

OTI

sequence resets the fault queue counter, so if there are three
readings greater than T

followed by a reading less than T

OTI

OTI

,

the fault queue counter is reset without triggering OTI.

POWER-ON DEFAULTS

The AD7416/AD7417/AD7418 always power up with the
following defaults:

• Address pointer pointing to temperature value register

comparator mode

• T

• T

= 80°C

OTI

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 have 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. After 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 tempera­ture 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 com­pleted conversion. The next conversion typically occurs 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.

With V
AD7418 spend 40 μs (or 10% of the time) in conversion mode.
The part spends 360 μs (or 90% of time) in partial power-down
mode. Thus, the average power dissipated by the AD7416/
AD7417/AD7418 is

= 3 V for each 400 μs cycle, the AD7416/AD7417/

DD

3 mW × 0.1 + 1 mW × 0.9 = 1.2 mW

AD7416/AD7417/AD7418

Mode 2

For applications where temperature measurements are required
at a slower rate, for example, 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 full power­down 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
dissipation.

Thus, the average power dissipation is

3 mW × 0.004 + 60 nW × 0.9996 = 1.2 μW

The fastest throughput rate at which the AD7416/AD7417/
AD7418 can be operated is 2.5 kHz (that is, a read every 400 μs
conversion period). Because T
read time with the I

2

C operating at 100 kbps would be 270 μs. If

OTI

and T

are 2-byte reads, the

HYST

temperature reads are called too often, reads will overlap with
conversions, aborting them continuously, which results in
invalid readings.

CONVST START MODE

The AD7417/AD7418 have an extra mode, set by writing to the
MSB of the Config2 register.

CONVST

Conversions are initiated only by using the
this method of operation,

The rising edge of
power-up time is 4 μs. If the
4 μs, a conversion is initiated on the falling edge of

Pin Mode

CONVST

CONVST

CONVST

is normally low.

starts the power-up time. This

CONVST

high time is longer than

CONVST

pin. In

and the track-and-hold also enters its hold mode at this time.

CONVST

If the
initiated by the rising edge of

high time is less than 4 μs, an internal timer,

CONVST

, holds off the track­and-hold and the initiation of conversion until the timer times
out (4 μs after the rising edge of
with the power-up time). The

CONVST

CONVST

, which corresponds

input remains low at
the end of conversion, thus causing the part to enter its power­down mode. In this method of operation,

CONVST

is normally
low with a high going pulse controlling the power-up, and the
conversion starts.

CONVST

The

pin should not be pulsed when reading from or

writing to the port.

Figure 21 shows the recommended minimum times for the
CONVST

Figure 22

pulse when the temperature channel is selected.

shows the minimum times an analog input channel is

selected.

100ns

CONVST

Figure 21.

40µs

CONVST

When Temperature Channel Selected

01126-023

100ns

CONVST

Figure 22.

CONVST

15µs

When V

Channel Selected

IN

01126-024

Rev. I | Page 18 of 24

AD7416/AD7417/AD7418

V

APPLICATIONS INFORMATION

SUPPLY DECOUPLING

The AD7416/AD7417/AD7418 should be decoupled with a

0.1 μF ceramic capacitor between V

and GND. This is

DD

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

pin is at 0 V. Refer to the AN-588 Application

DD

Note, AD7416/AD7417/AD7418 Power-On Reset Circuit at

www.analog.com 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 cannot start operating. The
output from the temperature value and ADC value registers will
be a constant value.

To restart the device operation, the registers 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—default value = 0x00

• Config2 register—default value = 0x00

• T

• T

setpoint register—default value = 0x4B00

HYST

setpoint register—default value = 0x5500

OTI

MOUNTING THE AD7416/AD7417/AD7418

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
is within about 0.2°C of the surface temperature, due to the low
power consumption of the device. Take care to insulate the back
and leads of the device from the air if the ambient air
temperature is different from the surface temperature being
measured.

The GND pin provides the best thermal path to the die, so the
temperature of the die is close to that of the printed circuit
ground track. Take care to ensure that this is in close thermal
contact with the surface being measured.

As with any IC, the AD7416/AD7417/AD7418 and its associated
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.

FAN CONTROLLER

Figure 23 shows a simple fan controller that switches on a
cooling fan when the temperature exceeds 80°C and switches it
off again when the temperature falls below 75°C. The AD7416
can be used as a standalone device 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.

12

V

DD

3V TO 5.5V

8

AD7416

4

R1
10kΩR210kΩ

3

Figure 23. AD7416 Used as a Fan Controller

Q1
2N3904
OR SIMILAR

Q2
LOGIC LEVEL
MOSFET RATED
TO SUIT FAN
CURRENT

01126-020

THERMOSTAT

Figure 24 shows the AD7416 used as a thermostat. The heater
switches on when the temperature falls below T
switches off again when the temperature rises above T
this application and for comparator mode, program the OTI
output active low.

V

DD

3V TO 5.5V

R1

8

AD7416

3

4

Figure 24. AD7416 Used as a Thermostat

10kΩ

RELAY

Q1
2N3904
OR SIMILAR

1N4001

D1

HYST

HEATER

RLA1

and

OTI

HEATER

SUPLY

. For

01126-021

Rev. I | Page 19 of 24

AD7416/AD7417/AD7418

V

3V

SYSTEM WITH MULTIPLE AD7416 DEVICES

The three LSBs of the AD7416 serial address can be set by the
user, allowing eight different addresses from 1001000 to

1001111. Figure 25 shows a system in which eight AD7416
devices are connected to a single serial bus, with their OTI
outputs wire-AND’ed together to form a common interrupt

DD

TO

5.5V

R1
10kΩ

8

7

3

6

2

5

1

AD7416

4

8

7

3

6

2

5

1

AD7416

4

8

7

3

6

2

5

1

AD7416

4

8

7

3

6

2

5

1

AD7416

4

Figure 25. Multiple Connection of AD7416 Devices to a Single Serial Bus

line. This arrangement means 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.

8

7

3

6

2

5

1

AD7416

4

8

7

3

6

2

5

1

AD7416

4

8

7

3

6

2

5

1

AD7416

4

8

7

3

6

2

5

1

AD7416

4

PROCESSOR

SUPER I/O CHIP

1126-022

Rev. I | Page 20 of 24

AD7416/AD7417/AD7418

OUTLINE DIMENSIONS

10.00 (0.3937)

9.80 (0.3858)

4.00 (0.1575)

3.80 (0.1496)

0.25 (0.0098)

0.10 (0.0039)

COPLANARITY

0.10

CONTROLLING DIME NSIONS ARE IN MIL LIMETERS ; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLYAND ARE NOT APPROPRIATE FOR USE I N DES IGN.

16

1

1.27 (0.0500)
BSC

0.51 (0.0201)

0.31 (0.0122)

COMPLIANT TO JEDEC STANDARDS MS-012-AC

9

8

6.20 (0.2441)

5.80 (0.2283)

1.75 (0.0689)

1.35 (0.0531)

SEATING
PLANE

8°
0°

0.25 (0.0098)

0.17 (0.0067)

0.50 (0.0197)

0.25 (0.0098)

1.27 (0.0500)

0.40 (0.0157)

45°

060606-A

Figure 26. 16-Lead Standard Small Outline Package [SOIC_N]

Narrow Body

(R-16)

Dimensions shown in millimeters and (inches)

5.00 (0.1968)

4.80 (0.1890)

4.00 (0.1574)

3.80 (0.1497)

0.25 (0.0098)

0.10 (0.0040)

COPLANARITY

0.10
SEATING

PLANE

85

1

1.27 (0.0500)
BSC

6.20 (0.2441)

5.80 (0.2284)

4

1.75 (0.0688)

1.35 (0.0532)

0.51 (0.0201)

0.31 (0.0122)

8°
0°

0.25 (0.0098)

0.17 (0.0067)

0.50 (0.0196)

0.25 (0.0099)

1.27 (0.0500)

0.40 (0.0157)

45°

CONTROLL ING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSI ONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ON LY AND ARE NO T APPROPRIATE FOR USE IN DESI GN.

COMPLIANT TO JEDEC STANDARDS MS-012-A A

012407-A

Figure 27. 8-Lead Standard Small Outline Package [SOIC_N]

Narrow Body

(R-8)

Dimensions shown in millimeters and (inches)

Rev. I | Page 21 of 24

AD7416/AD7417/AD7418

0

0

0

4.50

4.40

4.30

PIN 1

0.15

0.05

0.65

BSC

5.10

5.00

4.90

16

COPLANARITY

COMPLIANT TO JEDEC STANDARDS MO-153-AB

0.10

0.30

0.19

9

81

1.20
MAX

SEATING
PLANE

6.40
BSC

0.20

0.09
8°

0°

0.75

0.60

0.45

Figure 28. 16-Lead Thin Shrink Small Outline Package [TSSOP]

(RU-16)

Dimensions shown in millimeters

3.20

3.00

2.80

8

5

3.20

3.00

2.80

1

5.15

4.90

4.65

4

PIN 1

0.65 BSC

.95
.85
.75

0.15

0.38

0.00

0.22

COPLANARITY

0.10

COMPLIANT T O JEDE C ST ANDARDS MO-187-AA

1.10 MAX

SEATING
PLANE

0.23

0.08

8°
0°

0.80

0.60

0.40

Figure 29. 8-Lead Mini Small Outline Package [MSOP]

(RM-8)

Dimensions shown in millimeters

Rev. I | Page 22 of 24

AD7416/AD7417/AD7418

ORDERING GUIDE

Model1

AD7416AR −40°C to +125°C ±2°C 8-Lead Standard Small Outline Package (SOIC_N) R-8
AD7416AR-REEL −40°C to +125°C ±2°C 8-Lead Standard Small Outline Package (SOIC_N) R-8
AD7416AR-REEL7 −40°C to +125°C ±2°C 8-Lead Standard Small Outline Package (SOIC_N) R-8
AD7416ARZ −40°C to +125°C ±2°C 8-Lead Standard Small Outline Package (SOIC_N) R-8
AD7416ARZ-REEL −40°C to +125°C ±2°C 8-Lead Standard Small Outline Package (SOIC_N) R-8
AD7416ARZ-REEL7 −40°C to +125°C ±2°C 8-Lead Standard Small Outline Package (SOIC_N) R-8
AD7416ARM −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) C6A RM-8
AD7416ARM-REEL −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) C6A RM-8
AD7416ARM-REEL7 −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) C6A RM-8
AD7416ARMZ −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) C6A# RM-8
AD7416ARMZ-REEL −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) C6A# RM-8
AD7416ARMZ-REEL7 −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) C6A# RM-8
AD7417-WAFER Bare Die Wafer
AD7417AR −40°C to +125°C ±2°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417AR-REEL −40°C to +125°C ±2°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417AR-REEL7 −40°C to +125°C ±2°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417ARZ −40°C to +125°C ±2°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417ARZ-REEL −40°C to +125°C ±2°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417ARZ-REEL7 −40°C to +125°C ±2°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417ARU −40°C to +125°C ±2°C 16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7417ARU-REEL −40°C to +125°C ±2°C 16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7417ARU-REEL7 −40°C to +125°C ±2°C 16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7417ARUZ −40°C to +125°C ±2°C 16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7417ARUZ-REEL −40°C to +125°C ±2°C 16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7417ARUZ-REEL7 −40°C to +125°C ±2°C 16-Lead Thin Shrink Small Outline Package (TSSOP) RU-16
AD7417BR −40°C to +85°C ±1°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417BR-REEL −40°C to +85°C ±1°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417BR-REEL7 −40°C to +85°C ±1°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417BRZ −40°C to +85°C ±1°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417BRZ-REEL −40°C to +85°C ±1°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7417BRZ-REEL7 −40°C to +85°C ±1°C 16-Lead Standard Small Outline Package (SOIC_N) R-16
AD7418ACHIPS Die
AD7418ARZ −40°C to +125°C ±2°C 8-Lead Standard Small Outline Package (SOIC_N) R-8
AD7418ARZ-REEL −40°C to +125°C ±2°C 8-Lead Standard Small Outline Package (SOIC_N) R-8
AD7418ARZ-REEL7 −40°C to +125°C ±2°C 8-Lead Standard Small Outline Package (SOIC_N) R-8
AD7418ARM −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) C7A RM-8
AD7418ARM-REEL −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) C7A RM-8
AD7418ARM-REEL7 −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) C7A RM-8
AD7418ARMZ −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) T0G RM-8
AD7418ARMZ-REEL −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) T0G RM-8
AD7418ARMZ-REEL7 −40°C to +125°C ±2°C 8-Lead Mini Small Outline Package (MSOP) T0G RM-8
EVAL-AD7416/7/8EBZ Evaluation Board

1

Z = RoHS Compliant Part.

Temperature
Range

Temperature
Error Package Description Branding

Package
Option

Rev. I | Page 23 of 24

AD7416/AD7417/AD7418

NOTES

I2C refers to a communications protocol originally developed by Philips Semiconductors (Now NXP Semiconductors).

©1998–2010 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D01126-0-11/10(I)

Rev. I | Page 24 of 24