Changes to Ordering Guide .......................................................... 20
9/04—Rev. B to Rev. C
Changes to Ordering Guide .............................................................6
Changes to Operating Modes Section and Figure 16 ................ 13
Changes to Figure 17...................................................................... 14
Changes to AD7817 Serial Interface, Read Operation Section
and Figure 20................................................................................... 15
Changes to Figure 21...................................................................... 16
Rev. E | Page 2 of 20
Data Sheet
SPECIFICATIONS
AD7817/AD7818
V
DD
= 2.7 V to 5.5 V, GND = 0 V, REF
IN
= 2.5 V, unless otherwise noted. The
AD7817
temperature sensor is specified with an external
2.5 V reference, and the
AD7818
temperature sensor is specified with an on-chip reference. For V
DD
= 2.7 V, T
A
= 85°C maximum and
temperature sensor measurement error = ±3°C.
Table 1.
Parameter
DYNAMIC PERFORMANCE (AD7817 ONLY)
Signal-to-(Noise + Distortion) Ratio
2
Total Harmonic Distortion
2
Peak Harmonic or Spurious Noise
2
Intermodulation Distortion
2
Second-Order Terms
Third-Order Terms
Channel-to-Channel Isolation
2
DC ACCURACY (AD7817 ONLY)
Resolution
Minimum Resolution for Which No
Missing Codes are Guaranteed
Relative Accuracy
2
Differential Nonlinearity
2
Gain Error
2
Gain Error Match
2
Offset Error
2
Offset Error Match
TEMPERATURE SENSOR (AD7817 ONLY)
Measurement Error
Ambient Temperature 25°C
T
MIN
to T
MAX
Measurement Error
Ambient Temperature 25°C
T
MIN
to T
MAX
Temperature Resolution
REFERENCE INPUT (AD7817 ONLY)
3, 4
REF
IN
Input Voltage Range
3
Input Impedance
Input Capacitance
ON-CHIP REFERENCE (AD7817 ONLY)
5
Temperature Coefficient
3
CONVERSION RATE (AD7817 ONLY)
Track-and-Hold Acquisition Time
4
Conversion Time
Temperature Sensor
Channel 1 to Channel 4
A Version
1
B Version
1
S Version
1
Unit
Test Conditions/Comments
Sample rate = 100 kSPS, any channel,
f
IN
= 20 kHz
−75 dB typical
−75 dB typical
fa =19.9 kHz, fb = 20.1 kHz
58
–65
–65
–67
–67
–80
10
10
±1
±1
±2
±10
±1/2
±2
±1/2
58
−65
−65
−67
−67
−80
10
10
±1
±1
±2
±10
±1/2
±2
±1/2
58
−65
−65
−67
−67
−80
10
10
±1
±1
±2
+20/−10
±1/2
±2
±1/2
dB min
dB max
dB max
dB typ
dB typ
dB typ
Bits
f
IN
= 20 kHz
Any channel
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
External reference
Internal reference
External reference V
REF
= 2.5 V
±2
±3
±2.25
±3
1/4
2.625
2.375
40
10
80
400
27
9
±1
±2
±2.25
±3
1/4
2.625
2.375
40
10
80
400
27
9
±2
±3
±2.25
±6
1/4
2.625
2.375
40
10
150
400
27
9
°C max
°C max
On-chip reference
°C max
°C max
°C/LSB
V max
V min
kΩ min
pF max
ppm/°C typ
ns max
μs max
μs max
Source Impedance < 10 Ω
2.5 V + 5%
2.5 V − 5%
Nominal 2.5 V
Rev. E | Page 3 of 20
AD7817/AD7818
Parameter
POWER REQUIREMENTS (AD7817 ONLY)
V
DD
I
DD
Normal Operation
Using External Reference
Power-Down (V
DD
= 5 V)
Power-Down (V
DD
= 3 V)
Auto Power-Down Mode
10 SPS Throughput Rate
1 kSPS Throughput Rate
10 kSPS Throughput Rate
Power-Down
DYNAMIC PERFORMANCE (AD7818 ONLY)
6
Signal-to-(Noise + Distortion) Ratio
2
Total Harmonic Distortion
2
Peak Harmonic or Spurious Noise
2
Intermodulation Distortion
2
Second-Order Terms
Third-Order Terms
Channel-to-Channel Isolation
2
DC ACCURACY (AD7818 ONLY)
6
Resolution
Minimum Resolution for Which No
Missing Codes are Guaranteed
Relative Accuracy
2
Differential Nonlinearity
2
Gain Error
2
Offset Error
2
TEMPERATURE SENSOR (AD7818 ONLY)
6
Measurement Error
Ambient Temperature 25°C
T
MIN
to T
MAX
Measurement Error
Ambient Temperature 25°C
T
MIN
to T
MAX
Temperature Resolution
ON-CHIP REFERENCE (AD7818 ONLY)
5
Temperature Coefficient
3
CONVERSION RATE (AD7818 ONLY)
6
Track-and-Hold Acquisition Time
4
Conversion Time
Temperature Sensor
Channel 1
A Version
1
5.5
2.7
2
1.75
10
4
6.4
48.8
434
12
B Version
1
5.5
2.7
2
1.75
10
4
6.4
48.8
434
12
S Version
1
5.5
2.7
2
1.75
12.5
4.5
6.4
48.8
434
13.5
Unit
V max
V min
mA max
mA max
μA max
μA max
μW typ
μW typ
μW typ
μW max
Data Sheet
Test Conditions/Comments
For specified performance
Logic inputs = 0 V or V
DD
1.6 mA typical
2.5 V external reference connected
5.5 μA typical
2 μA typical
V
DD
= 3 V
See the Power vs. Throughput
section for description of power
dissipation in auto power-down mode
Typically 6 μW
Sample rate = 100 kSPS, any channel,
f
IN
= 20 kHz
−75 dB typical
−75 dB typical
fa = 19.9 kHz, fb = 20.1 kHz
57
–65
–67
–67
–67
–80
10
10
±1
±1
±10
±4
dB min
dB max
dB typ
dB typ
dB typ
dB typ
Bits
Bits
LSB max
LSB max
LSB max
LSB max
f
IN
= 20 kHz
Any channel
Internal reference V
REF
= 2.5 V
±2
±3
±2
±3
1/4
30
400
27
9
°C max
°C max
On-chip reference
°C max
°C max
°C/LSB
Nominal 2.5 V
ppm/°C typ
ns max
μs max
μs max
Source impedance < 10 Ω
Rev. E | Page 4 of 20
Data Sheet
Parameter
POWER REQUIREMENTS (AD7818 ONLY)
6
V
DD
I
DD
Normal Operation
Using External Reference
Power-Down (V
DD
= 5 V)
Power-Down (V
DD
= 3 V)
Auto Power-Down Mode
10 SPS Throughput Rate
1 kSPS Throughput Rate
10 kSPS Throughput Rate
Power-Down
ANALOG INPUTS (AD7817/AD7818)
7
Input Voltage Range
Input Leakage
Input Capacitance
LOGIC INPUTS (AD7817/AD7818)
4
Input High Voltage, V
INH
Input Low Voltage, V
INL
Input High Voltage, V
INH
Input Low Voltage, V
INL
Input Current, I
IN
Input Capacitance, C
IN
LOGIC OUTPUTS (AD7817/AD7818)
4
Output High Voltage, V
OH
A Version
1
5.5
2.7
2
1.75
10.75
4.5
6.4
48.8
434
13.5
V
REF
0
±1
10
2.4
0.8
2
0.4
±3
10
V
REF
0
±1
10
2.4
0.8
2
0.4
±3
10
V
REF
0
±1
10
2.4
0.8
2
0.4
±3
10
B Version
1
S Version
1
Unit
V max
V min
mA max
mA max
μA max
μA max
μW typ
μW typ
μW typ
μW max
V max
V min
μA min
pF max
V min
V max
V min
V max
μA max
pF max
AD7817/AD7818
Test Conditions/Comments
For specified performance
Logic inputs = 0 V or V
DD
1.3 mA typical
2.5 V internal reference connected
6 μA typ
2 μA typ
V
DD
= 3 V
See the Power vs. Throughput section
for description of power dissipation
in auto power-down mode
Typically 6 μW
V
DD
= 5 V ±10%
V
DD
= 5 V ±10%
V
DD
= 3 V ±10%
V
DD
= 3 V ±10%
Typically 10 nA, V
IN
= 0 V to V
DD
4
2.4
Output Low Voltage, V
OL
0.4
0.2
±1
15
4
2.4
0.4
0.2
±1
15
4
2.4
0.4
0.2
±1
15
V min
V min
V max
V max
μA max
pF max
I
SOURCE
= 200 μA
V
DD
= 5 V ± 10%
V
DD
= 3 V ± 10%
I
SINK
= 200 μA
V
DD
= 5 V ± 10%
V
DD
= 3 V ± 10%
High Impedance Leakage Current
High Impedance Capacitance
1
2
The B Version and the S Version only apply to the
AD7817.
The A Version applies to the
AD7817
or the
AD7818
(as stated in specification).
See Terminology.
3
The accuracy of the temperature sensor is affected by reference tolerance. The relationship between the two is explained in the Temperature Measurement Error Due
to Reference Error section.
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
These specifications are typical for
AD7818
at temperatures above 85°C and with V
DD
greater than 3.6 V.
7
This refers to the input current when the part is not converting. Primarily due to the reverse leakage current in the ESD protection diodes.
