AD7792/AD7793
Rev. B | Page 4 of 32
Parameter AD7792B/AD7793B
1
Unit Test Conditions/Comments
REFERENCE
Internal Reference
Internal Reference Initial Accuracy 1.17 ± 0.01% V min/max AV
DD
= 4 V, T
A
= 25°C
Internal Reference Drift
2
4 ppm/°C typ
15 ppm/°C max
Power Supply Rejection 85 dB typ
External Reference
External REFIN Voltage 2.5 V nom
REFIN = REFIN(+) REFIN()
Reference Voltage Range
2
0.1 V min
AV
DD
V max
When V
REF
= AV
DD
, the differential input must be
limited to 0.9 × V
REF
/gain if the in-amp is active
Absolute REFIN Voltage Limits
2
GND 30 mV
V min
AV
DD
+ 30 mV V max
Average Reference Input Current 400 nA/V typ
Average Reference Input Current
Drift
±0.03 nA/V/°C typ
Normal Mode Rejection Same as for analog inputs
Common-Mode Rejection 100 dB typ
EXCITATION CURRENT SOURCES
(IEXC1 and IEXC2)
Output Current 10/210/1000 μA nom
Initial Tolerance at 25°C ±5 % typ
Drift 200 ppm/°C typ
Current Matching ±0.5 % typ Matching between IEXC1 and IEXC2; V
OUT
= 0 V
Drift Matching 50 ppm/°C typ
Line Regulation (V
DD
) 2 %/V typ AV
DD
= 5 V ± 5%
Load Regulation 0.2 %/V typ
Output Compliance
AV
DD
0.65
V max 10 μA or 210 μA currents selected
AV
DD
1.1
V max 1 mA currents selected
GND 30 mV
V min
TEMPERATURE SENSOR
Accuracy
Sensitivity
±2
0.81
°C typ
mV/°C typ
Applies if user calibrates the temperature
sensor
BIAS VOLTAGE GENERATOR
V
BIAS
AV
DD
/2 V nom
V
BIAS
Generator Start-Up Time See Figure 10 ms/nF typ Dependent on the capacitance on the AIN pin
INTERNAL/EXTERNAL CLOCK
Internal Clock
Frequency
2
64 ± 3% kHz min/max
Duty Cycle 50:50 % typ
External Clock
Frequency 64 kHz nom
A 128 kHz external clock can be used if the
divide-by-2 function is used
(Bit CLK1 = CLK0 = 1)
Duty Cycle 45:55 to 55:45 % typ
Applies for external 64 kHz clock; a 128 kHz
clock can have a less stringent duty cycle
LOGIC INPUTS
CS
2
V
INL
, Input Low Voltage 0.8 V max DV
DD
= 5 V
V
INH
, Input High Voltage
0.4
2.0
V max
V min
DV
DD
= 3 V
DV
DD
= 3 V or 5 V
AD7792/AD7793
Rev. B | Page 5 of 32
Parameter AD7792B/AD7793B
1
Unit Test Conditions/Comments
SCLK, CLK, and DIN (Schmitt-
Triggered Input)
2
V
T
(+) 1.4/2 V min/V max DV
DD
= 5 V
V
T
(–) 0.8/1.7 V min/V max DV
DD
= 5 V
V
T
(+) V
T
()
0.1/0.17 V min/V max DV
DD
= 5 V
V
T
(+) 0.9/2 V min/V max DV
DD
= 3 V
V
T
(–) 0.4/1.35 V min/V max DV
DD
= 3 V
V
T
(+) V
T
()
0.06/0.13 V min/V max DV
DD
= 3 V
Input Currents
Input Capacitance
±10
10
μA max
pF typ
V
IN
= DV
DD
or GND
All digital inputs
LOGIC OUTPUTS (INCLUDING CLK)
V
OH
, Output High Voltage
2
DV
DD
0.6
V min DV
DD
= 3 V, I
SOURCE
= 100 μA
V
OL
, Output Low Voltage
2
0.4 V max DV
DD
= 3 V, I
SINK
= 100 μA
V
OH
, Output High Voltage
2
4 V min DV
DD
= 5 V, I
SOURCE
= 200 μA
V
OL
, Output Low Voltage
2
0.4 V max
DV
DD
= 5 V, I
SINK
= 1.6 mA (DOUT/RDY)/800 μA
(CLK)
Floating-State Leakage Current ±10 μA max
Floating-State Output Capacitance 10 pF typ
Data Output Coding Offset binary
SYSTEM CALIBRATION
2
Full-Scale Calibration Limit +1.05 × FS V max
Zero-Scale Calibration Limit
1.05 × FS
V min
Input Span 0.8 × FS V min
2.1 × FS V max
POWER REQUIREMENTS
7
Power Supply Voltage
AV
DD
to GND
2.7/5.25 V min/max
DV
DD
to GND
2.7/5.25 V min/max
Power Supply Currents
I
DD
Current 140 μA max
110 μA typ @ AV
DD
= 3 V, 125 μA typ @ AV
DD
= 5 V,
unbuffered mode, external reference
185 μA max
130 μA typ @ AV
DD
= 3 V, 165 μA typ @ AV
DD
= 5 V,
buffered mode, gain = 1 or 2, external reference
400 μA max
300 μA typ @ AV
DD
= 3 V, 350 μA typ @ AV
DD
= 5 V,
gain = 4 to 128, external reference
500 μA max
400 μA typ @ AV
DD
= 3 V, 450 μA typ @ AV
DD
= 5 V,
gain = 4 to 128, internal reference
I
DD
(Power-Down Mode) 1 μA max
1
Temperature range is –40°C to +105°C. At the 19.6 Hz and 39.2 Hz update rates, the INL, power supply rejection (PSR), common-mode rejection (CMR), and normal
mode rejection (NMR) do not meet the data sheet specification if the voltage on the AIN(+) or AIN(−) pins exceed AV
DD
− 16 V typically. When this voltage is exceeded,
the INL, for example, is reduced to 18 ppm of FS typically while the PSR is reduced to 69 dB typically. Therefore, for guaranteed performance at these update rates, the
absolute voltage on the analog input pins needs to be below AV
DD
− 1.6 V.
2
Specification is not production tested, but is supported by characterization data at initial product release.
3
Following a calibration, this error is in the order of the noise for the programmed gain and update rate selected.
4
Recalibration at any temperature removes these errors.
5
Full-scale error applies to both positive and negative full-scale and applies at the factory calibration conditions (AV
DD
= 4 V, gain = 1, T
A
= 25°C).
6
FS[3:0] are the four bits used in the mode register to select the output word rate.
7
Digital inputs equal to DV
DD
or GND with excitation currents and bias voltage generator disabled.
AD7792/AD7793
Rev. B | Page 6 of 32
TIMING CHARACTERISTICS
AV
DD
= 2.7 V to 5.25 V, DV
DD
= 2.7 V to 5.25 V, GND = 0 V, Input Logic 0 = 0 V, Input Logic 1 = DV
DD
, unless otherwise noted.
Table 2.
Parameter
1, 2
Limit at T
MIN
, T
MAX
(B Version) Unit Conditions/Comments
t
3
100 ns min SCLK high pulse width
t
4
100 ns min SCLK low pulse width
Read Operation
t
1
0 ns min
CS falling edge to DOUT/RDY active time
60 ns max DV
DD
= 4.75 V to 5.25 V
80 ns max DV
DD
= 2.7 V to 3.6 V
t
2
3
0 ns min SCLK active edge to data valid delay
4
60 ns max DV
DD
= 4.75 V to 5.25 V
80 ns max DV
DD
= 2.7 V to 3.6 V
t
5
5, 6
10 ns min
Bus relinquish time after
CS inactive edge
80 ns max
t
6
0 ns min
SCLK inactive edge to
CS inactive edge
t
7
10 ns min
SCLK inactive edge to DOUT/
RDY high
Write Operation
t
8
0 ns min
CS falling edge to SCLK active edge setup time
4
t
9
30 ns min Data valid to SCLK edge setup time
t
10
25 ns min Data valid to SCLK edge hold time
t
11
0 ns min
CS rising edge to SCLK edge hold time
1
Sample tested during initial release to ensure compliance. All input signals are specified with t
R
= t
F
= 5 ns (10% to 90% of DV
DD
) and timed from a voltage level of 1.6 V.
2
See Figure 3 and Figure 4.
3
These numbers are measured with the load circuit shown in Figure 2 and defined as the time required for the output to cross the V
OL
or V
OH
limits.
4
SCLK active edge is falling edge of SCLK.
5
These numbers are derived from the measured time taken by the data output to change 0.5 V when loaded with the circuit shown in Figure 2. 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.
6
RDY
returns high after a read of the ADC. In single conversion mode and continuous conversion mode, the same data can be read again, if required, while
RDY
is high,
although care should be taken to ensure that subsequent reads do not occur close to the next output update. In continuous read mode, the digital word can be read
only once.
0
4855-002
I
SINK
(1.6mA WITH DV
DD
= 5V,
100µA WITH DV
DD
= 3V)
I
SOURCE
(200µA WITH DV
DD
= 5V,
100µA WITH DV
DD
= 3V)
1.6V
TO
OUTPUT
PIN
50pF
Figure 2. Load Circuit for Timing Characterization

AD7793BRUZ-REEL

Mfr. #:
Manufacturer:
Analog Devices Inc.
Description:
Analog to Digital Converters - ADC 3Ch Lo Noise Lo Pwr 24B w/ On-Chip Ref
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union