Datasheet
ADS8634
ADS8638
www.ti.com
SBAS541A –MAY 2011– REVISED AUGUST 2011
ELECTRICAL CHARACTERISTICS: ADS8634, ADS8638
Minimum/maximum specifications at T
A
= –40°C to +125°C, f
SAMPLE
= 1MSPS, HVDD = 10V to 15V, HVSS = –10V to –15V,
AVDD = 4.75V to 5.25V, DVDD = 2.7V to 3.6V, and V
REF
= 2.5V, unless otherwise noted. Typical specifications at +25°C,
f
SAMPLE
= 1MHz, HVDD = 10V, HVSS = –10V, AVDD = 3.3V, DVDD = 3.3V, and V
REF
= 2.5V, unless otherwise noted.
ADS8634, ADS8638
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
ANALOG INPUT
±2.5 V
Bipolar ranges, V
REF
= 2.5V ±5 V
Full-scale input span
(1)
±10 V
0 to 5 V
Unipolar ranges, V
REF
= 2.5V
0 to 10 V
AINx absolute input range HVSS HVDD V
AINGND absolute input range –0.2 0.2 V
Input capacitance 8 pF
Input leakage current At +125°C 200 nA
SYSTEM PERFORMANCE
Resolution 12 Bits
No missing codes 12 Bits
Integral linearity –1.5 +0.9/–0.9 1.5 LSB
(2)
Differential linearity –1.0 +0.9/–0.5 1.6 LSB
Offset error
(3)
–3 ±0.8 3 LSB
ppmFS/°C
(
Offset error drift 0.75
4)
Gain error
(5)
–8 ±2 8 LSB
Gain error drift 1.2 ppm/°C
Noise 0.33 LSB
At FFCh output code with
Power-supply rejection –87 dB
250mV
PP
and 480Hz ripple on AVDD
Crosstalk on channel 0 with channel 0 permanently selected,
Isolation
2kHz full-scale sine wave on channel 1, all other channels –110 dB
crosstalk
grounded
Crosstalk
Crosstalk on channel 0, 2kHz full-scale sine wave on channel 1,
Memory crosstalk all other channels grounded, device scans channel 0 and –81 dB
channel 1 alternately
SAMPLING DYNAMICS
Conversion time At 20MHz SCLK, DVDD = 2.7V to 5.25V 750 ns
Acquisition time AVDD = 2.7V to 5.25V 250 ns
Maximum throughput rate At 20MHz SCLK, DVDD = 2.7V to 5.25V 1 1 MSPS
Aperture delay 13 ns
Step response 250 ns
(1) Ideal input span; does not include gain or offset error.
(2) LSB means least significant bit.
(3) Measured relative to an ideal full-scale input.
(4) ppmFS/°C is drift measured in parts per million of full-scale range per degree centigrade.
(5) Does not include reference drift.
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