Analog Devices AD7818ARM, AD7817SR, AD7817BRU, AD7817BR, AD7817ARU Datasheet

REV. B

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a

AD7816/AD7817/AD7818

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Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 2000

Single- and 4-Channel, 9 ␮s, 10-Bit ADCs

with On-Chip Temperature Sensor

FUNCTIONAL BLOCK DIAGRAM

FEATURES
10-Bit ADC with 9 ␮s Conversion Time
One (AD7818) and Four (AD7817) Single-Ended Analog

Input Channels
The AD7816 Is a Temperature Measurement Only Device
On-Chip Temperature Sensor

Resolution of 0.25ⴗC

ⴞ2ⴗC Error from –40ⴗC to +85ⴗC

–55ⴗC to +125ⴗC Operating Range
Wide Operating Supply Range

2.7 V to 5.5 V
Inherent Track-and-Hold Functionality
On-Chip Reference (2.5 V ⴞ 1%)
Over-Temperature Indicator
Automatic Power-Down at the End of a Conversion
Low Power Operation

4 ␮W at a Throughput Rate of 10 SPS
40 ␮W at a Throughput Rate of 1 kSPS
400 ␮W at a Throughput Rate of 10 kSPS

Flexible Serial Interface

APPLICATIONS
Ambient Temperature Monitoring (AD7816)

Thermostat and Fan Control
High Speed Microprocessor
Temperature Measurement and Control

Data Acquisition Systems with Ambient Temperature

Monitoring (AD7817 and AD7818)

Industrial Process Control
Automotive
Battery Charging Applications

GENERAL DESCRIPTION

The AD7818 and AD7817 are 10-bit, single- and 4-channel
A/D converters with on-chip temperature sensor that can oper­ate from a single 2.7 V to 5.5 V power supply. Each part con­tains a 9 µs successive-approximation converter based around
a capacitor DAC, an on-chip temperature sensor with an accu­racy of ± 2°C, an on-chip clock oscillator, inherent track-and­hold functionality and an on-chip reference (2.5 V). The
AD7816 is a temperature monitoring only device in a SOIC/
µSOIC package.

The on-chip temperature sensor of the AD7817 and AD7818
can be accessed via 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
with a resolution of ±0.25°C. See Measuring Temperature section
of the data sheet.

The AD7816, AD7817, and AD7818 have a flexible serial
interface that allows easy interfacing to most microcontrollers.
The interface is compatible with the Intel 8051, Motorola
SPI™ and QSPI™ protocols and National Semiconductors
MICROWIRE™ protocol. For more information refer to the
Serial Interface section of this data sheet.

The AD7817 is available in a narrow body 0.15" 16-lead Small
Outline IC (SOIC), in a 16-lead, Thin Shrink Small Outline
Package (TSSOP), while the AD7816/AD7818 come in an
8-lead Small Outline IC (SOIC) and an 8-lead microsmall
Outline IC (µSOIC).

PRODUCT HIGHLIGHTS

1. The devices have an on-chip temperature sensor that allows an
accurate measurement of the ambient temperature to be
made. The measurable temperature range is –55°C to +125°C.

2. An over-temperature 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 over­temperature register. The over-temperature indicator pin goes
logic low when a predetermined temperature is exceeded.

3. The automatic power-down feature enables the AD7816,
AD7817, and AD7818 to achieve superior power perfor­mance at slower throughput rates, e.g., 40 µW at 1 kSPS
throughput rate.

SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corporation.

CHARGE

REDISTRIBUTION

DAC

CLOCK

D

OUT

SCLK
RD/WR

CONVST

AGND

CONTROL

REG

A

B

OVER-TEMP

REG

A > B

OTI

CONTROL

LOGIC

V

BALANCE

SAMPLING

CAPACITOR

MUX

REF

2.5V

TEMP

SENSOR

REF

IN

V

DD

DATA

OUT

D

IN

DGND

BUSY

CS

V

IN1

V

IN2

V

IN3

V

IN4

AD7817

–2–

REV. B

AD7816/AD7817/AD7818

Parameter A Version *B Version *S Version Unit Test Conditions/Comments

DYNAMIC PERFORMANCE Sample Rate = 100 kSPS, Any

Channel, f

IN

= 20 kHz

Signal to (Noise + Distortion) Ratio

2

58 58 58 dB min

Total Harmonic Distortion

2

–65 –65 –65 dB max –75 dB typ

Peak Harmonic or Spurious Noise

2

–65 –65 –65 dB max –75 dB typ

Intermodulation Distortion

2

fa =19.9 kHz, fb = 20.1 kHz
Second Order Terms –67 –67 –67 dB typ
Third Order Terms –67 –67 –67 dB typ

Channel-to-Channel Isolation

2

–80 –80 –80 dB typ fIN = 20 kHz

DC ACCURACY Any Channel

Resolution 10 10 10 Bits
Minimum Resolution for Which

No Missing Codes are Guaranteed 10 10 10 Bits

Relative Accuracy

2

± 1 ± 1 ± 1LSB max

Differential Nonlinearity

2

± 1 ± 1 ± 1LSB max

Gain Error

2

± 2 ± 2 ± 2 LSB max External Reference
± 10 ± 10 +20/–10 LSB max Internal Reference

Gain Error Match

2

± 1/2 ±1/2 ± 1/2 LSB max

Offset Error

2

± 2 ± 2 ± 2LSB max

Offset Error Match ± 1/2 ± 1/2 ± 1/2 LSB max

TEMPERATURE SENSOR

1

Measurement Error External Reference V

REF

= 2.5 V
Ambient Temperature 25°C ± 2 ± 1 ± 2 °C max
T

MIN

to T

MAX

± 3 ± 2 ± 3 °C max

Measurement Error On-Chip Reference

Ambient Temperature 25°C ± 2.25 ± 2.25 ±2.25 °C max
T

MIN

to T

MAX

± 3 ± 3 ± 6 °C max

Temperature Resolution 1/4 1/4 1/4 °C/LSB

REFERENCE INPUT

3, 4

REFIN Input Voltage Range

3

2.625 2.625 2.625 V max 2.5 V + 5%

2.375 2.375 2.375 V min 2.5 V – 5%
Input Impedance 40 40 40 kΩ min
Input Capacitance 10 10 10 pF max

ON-CHIP REFERENCE

5

Nominal 2.5 V

Temperature Coefficient

3

80 80 150 ppm/°C typ

CONVERSION RATE

Track/Hold Acquisition Time

4

400 400 400 ns max Source Impedance < 10 Ω

Conversion Time

Temperature Sensor 27 27 27 µs max
Channels 1 to 4 9 9 9 µs max

POWER REQUIREMENTS

V

DD

5.5 5.5 5.5 V max For Specified Performance

2.7 2.7 2.7 V min
I

DD

Logic Inputs = 0 V or V

DD

Normal Operation 2 2 2 mA max 1.6 mA typ
Using External Reference 1.75 1.75 1.75 mA max 2.5 V External Reference Connected
Power-Down (V

DD

= 5 V) 10 10 12.5 µA max 5.5 µA typ

Power-Down (V

DD

= 3 V) 4 4 4.5 µA max 2 µA typ

Auto Power-Down Mode V

DD

= 3 V
10 SPS Throughput Rate 6.4 6.4 6.4 µW typ See Power vs. Throughput Section
1 kSPS Throughput Rate 48.8 48.8 48.8 µW typ for Description of Power Dissipa-
10 kSPS Throughput Rate 434 434 434 µW typ tion in Auto Power-Down Mode

Power-Down 12 12 13.5 µW max Typically 6 µW

AD7817–SPECIFICATIONS

1

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

–3–REV. B

AD7816/AD78186–SPECIFICATIONS

1

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

Parameter A Version Unit Test Conditions/Comments

DYNAMIC PERFORMANCE (AD7818 Only) Sample Rate = 100 kSPS, Any Channel,

fIN = 20 kHz

Signal to (Noise + Distortion) Ratio

2

57 dB min

Total Harmonic Distortion

2

–65 dB max –75 dB typ

Peak Harmonic or Spurious Noise

2

–67 dB typ –75 dB typ

Intermodulation Distortion

2

fa = 19.9 kHz, fb = 20.1 kHz
Second Order Terms –67 dB typ
Third Order Terms –67 dB typ

Channel-to-Channel Isolation

2

–80 dB typ fIN = 20 kHz

DC ACCURACY (AD7818 Only) Any Channel

Resolution 10 Bits
Minimum Resolution for Which

No Missing Codes are Guaranteed 10 Bits

Relative Accuracy

2

± 1LSB max

Differential Nonlinearity

2

± 1LSB max

Gain Error

2

± 10 LSB max

Offset Error

2

± 4LSB max

TEMPERATURE SENSOR

1

Measurement Error External Reference V

REF

= 2.5 V
Ambient Temperature 25°C ± 2 °C max
T

MIN

to T

MAX

± 3 °C max

Measurement Error On-Chip Reference

Ambient Temperature 25°C ± 2 °C max
T

MIN

to T

MAX

± 3 °C max

Temperature Resolution 1/4 °C/LSB

REFERENCE INPUT

3, 4

(AD7816 Only)

REF

IN

Input Voltage Range

3

2.625 V max 2.5 V + 5%

2.375 V min 2.5 V – 5%
Input Impedance 50 kΩ min
Input Capacitance 10 pF max

ON-CHIP REFERENCE

5

Nominal 2.5 V

Temperature Coefficient

3

30 ppm/°C typ

CONVERSION RATE

Track/Hold Acquisition Time

4

400 ns max Source Impedance < 10 Ω

Conversion Time

Temperature Sensor 27 µs max
Channel 1 9 µs max (AD7818 Only)

POWER REQUIREMENTS

V

DD

5.5 V max For Specified Performance

2.7 V min
I

DD

Logic Inputs = 0 V or V

DD

Normal Operation 2 mA max 1.3 mA typ
Using External Reference 1.75 mA max 2.5 V External Reference Connected
Power-Down (V

DD

= 5 V) 10.75 µA max 6 µA typ

Power-Down (V

DD

= 3 V) 4.5 µA max 2 µA typ

Auto Power-Down Mode V

DD

= 3 V
10 SPS Throughput Rate 6.4 µW typ See Power vs. Throughput Section for
1 kSPS Throughput Rate 48.8 µW typ Description of Power Dissipation in
10 kSPS Throughput Rate 434 µW typ Auto Power-Down Mode

Power-Down 13.5 µW max Typically 6 µW

AD7816/AD7817/AD7818

–4–

Parameter A Version *B Version *S Version Unit Test Conditions/Comments

ANALOG INPUTS

7

(AD7817 and AD7818)

Input Voltage Range V

REF

V

REF

V

REF

V max

000V min
Input Leakage ± 1 ± 1 ± 1 µA min
Input Capacitance 10 10 10 pF max

LOGIC INPUTS

4

Input High Voltage, V

INH

2.4 2.4 2.4 V min VDD = 5 V ± 10%

Input Low Voltage, V

INL

0.8 0.8 0.8 V max VDD = 5 V ± 10%

Input High Voltage, V

INH

222V minV

DD

= 3 V ± 10%

Input Low Voltage, V

INL

0.4 0.4 0.4 V max VDD = 3 V ± 10%

Input Current, I

IN

± 3 ± 3 ± 3 µA max Typically 10 nA, VIN = 0 V to V

DD

Input Capacitance, C

IN

10 10 10 pF max

LOGIC OUTPUTS

4

Output High Voltage, V

OH

I

SOURCE

= 200 µA

444V minV

DD

= 5 V ± 10%

2.4 2.4 2.4 V min V

DD

= 3 V ± 10%

Output Low Voltage, V

OL

I

SINK

= 200 µA

0.4 0.4 0.4 V max V

DD

= 5 V ± 10%

0.2 0.2 0.2 V max V

DD

= 3 V ± 10%
High Impedance Leakage Current ± 1 ± 1 ± 1 µA max
High Impedance Capacitance 15 15 15 pF max

NOTES
*B and S Versions apply to AD7817 only. For operating temperature ranges, see Ordering Guide.

1

AD7816 and AD7817 temperature sensors specified with external 2.5 V reference, AD7818 specified with on-chip reference. All other specifications with external
and on-chip reference (2.5 V). For VDD = 2.7 V, TA = 85°C max and temperature sensor measurement error = ± 3°C.

2

See Terminology.

3

The accuracy of the temperature sensor is affected by reference tolerance. The relationship between the two is explained in the section titled Temperature Measure­ment Error Due to Reference Error.

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

All specifications are typical for AD7818 at temperatures above 85°C and with VDD greater than 3.6 V.

7

Refers to the input current when the part is not converting. Primarily due to reverse leakage current in the ESD protection diodes.

Specifications subject to change without notice.

CHARGE

REDISTRIBUTION

DAC

CLOCK

DATA

OUT

D

IN/

OUT

SCLK

RD/WR

CONVST

AGND

CONTROL

REG

A

B

OVER-TEMP

REG

A > B

OTI

CONTROL

LOGIC

V

BALANCE

SAMPLING

CAPACITOR

MUX

REF

2.5V

TEMP

SENSOR

REF

IN

V

DD

AD7816

Figure 1. AD7816 Functional Block Diagram

CHARGE

REDISTRIBUTION

DAC

CLOCK

GENERATOR

DATA

OUT

D

IN/

OUT

SCLK

RD/WR

CONVST

AGND

CONTROL

REG

A

B

OVER-TEMP

REG

A > B

OTI

CONTROL

LOGIC

V

BALANCE

SAMPLING

CAPACITOR

MUX

REF

2.5V

TEMP

SENSOR

V

DD

V

IN1

AD7818

Figure 2. AD7818 Functional Block Diagram

AD7816/AD7817/AD7818–SPECIFICATIONS

1

REV. B

AD7816/AD7817/AD7818

–5–REV. B

TIMING CHARACTERISTICS

1, 2

Parameter A, B Versions Unit Test Conditions/Comments

t

POWER-UP

2 µs max Power-Up Time from Rising Edge of CONVST

t

1a

9 µs max Conversion Time Channels 1 to 4

t

1b

27 µs max Conversion Time Temperature Sensor

t

2

20 ns min CONVST Pulsewidth

t

3

50 ns max CONVST Falling Edge to BUSY Rising Edge

t

4

0 ns min CS Falling Edge to RD/WR Falling Edge Setup Time

t

5

0 ns min RD/WR Falling Edge to SCLK Falling Edge Setup

t

6

10 ns min DIN Setup Time before SCLK Rising Edge

t

7

10 ns min DIN Hold Time after SCLK Rising Edge

t

8

40 ns min SCLK Low Pulsewidth

t

9

40 ns min SCLK High Pulsewidth

t

10

0 ns min CS Falling Edge to RD/WR Rising Edge Setup Time

t

11

0 ns min RD/WR Rising Edge to SCLK Falling Edge Setup Time

t

12

3

20 ns max D

OUT

Access Time after RD/WR Rising Edge

t

13

3

20 ns max D

OUT

Access Time after SCLK Falling Edge

t

14a

3, 4

30 ns max D

OUT

Bus Relinquish Time after Falling Edge of RD/WR

t

14b

3, 4

30 ns max D

OUT

Bus Relinquish Time after Rising Edge of CS

t

15

150 ns max BUSY Falling Edge to OTI Falling Edge

t

16

40 ns min RD/WR Rising Edge to OTI Rising Edge

t

17

400 ns min SCLK Rising Edge to CONVST Falling Edge (Acquisition Time of T/H)

NOTES

1

Sample tested during initial release and after any redesign or process change that may affect this parameter. All input signals are measured with tr = tf = 1 ns (10% to
90% of 5 V) and timed from a voltage level of 1.6 V.

2

See Figures 16, 17, 20 and 21.

3

These figures are measured with the load circuit of Figure 3. They are defined as the time required for D

OUT

to cross 0.8 V or 2.4 V for VDD = 5 V ± 10% and 0.4 V

or 2 V for VDD = 3 V ± 10%, as quoted on the specifications page of this data sheet.

4

These times are derived from the measured time taken by the data outputs to change 0.5 V when loaded with the circuit of Figure 3. The measured number is then
extrapolated back to remove the effects of charging or discharging the 50 pF capacitor. This means that the times quoted in the timing characteristics are the true bus
relinquish times of the part and as such are independent of external bus loading capacitances.

Specifications subject to change without notice.

1.6V

I

OL

200␮A

200␮A

I

OL

TO

OUTPUT

PIN

C

L

50pF

Figure 3. Load Circuit for Access Time and Bus Relinquish Time

(VDD = 2.7 V to 5.5 V, GND = 0 V, REFIN = 2.5 V. All specifications T

MIN

to T

MAX

unless

otherwise noted)