Datasheet
ADS7945
ADS7946
www.ti.com
SBAS539B –JUNE 2011– REVISED SEPTEMBER 2011
ELECTRICAL CHARACTERISTICS: ADS7946 (Single-Ended)
Minimum/maximum specifications at T
A
= –40°C to +125°C, AVDD = 2.7 V to 5.25 V, DVDD = 1.65 V to AVDD,
and f
SAMPLE
= 2 MSPS, unless otherwise noted.
Typical specifications at T
A
= +25°C, AVDD = 5 V, DVDD = 1.8 V, and f
SAMPLE
= 2 MSPS.
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
ANALOG INPUT
Full-scale input span
(1)
AINx – AINxGND 0 V
REF
V
AIN0, AIN1 –0.2 AVDD + 0.2 V
Absolute input range
AIN0GND, AIN1GND –0.2 0.2 V
Input capacitance
(2)
32 pF
Input leakage current At +125°C 1.5 nA
SYSTEM PERFORMANCE
Resolution 14 Bits
No missing codes 14 Bits
Integral linearity –2.5 ±1.25 2.5 LSB
(3)
Differential linearity –1 ±0.8 2.0 LSB
Offset error
(4)
–4 ±1.5 4 LSB
Gain error –4 ±1.5 4 LSB
Transition noise 25 µV
RMS
Power-supply rejection With 500 Hz sine wave on AVDD 60 dB
SAMPLING DYNAMICS
Conversion time 16 SCLK
Acquisition time 80 ns
Maximum sample rate (throughput rate) 40 MHz SCLK with a 16-clock frame 2 MSPS
Aperture delay
(5)
10 ns
Aperture jitter
(5)
10 ps
Step response
(5)(2)
80 ns
DYNAMIC CHARACTERISTICS
Total harmonic distortion (THD)
(6)
20 kHz, V
REF
= 4.0 V –85 dB
20 kHz, V
REF
= 4.0 V 79 82 dB
Signal-to-noise ratio (SNR)
100 kHz, V
REF
= 4.0 V 80 dB
Signal-to-noise and distortion ratio (SINAD) 20 kHz, V
REF
= 4.0 V 78.8 dB
Spurious-free dynamic range (SFDR) 20 kHz, V
REF
= 4.0 V 86 dB
Full-power bandwidth
(7)
At –3 dB 15 MHz
DIGITAL INPUT/OUTPUT
Logic family CMOS
V
IH
0.7DVDD V
V
IL
0.3DVDD V
Logic level
V
OH
SDO load 20 pF 0.8DVDD V
V
OL
SDO load 20 pF 0.2DVDD V
Input leakage current I
IH
, I
IL
0 < V
IN
< DVDD ±20 nA
External reference 2.5 AVDD V
(1) Ideal input span; does not include gain or offset error.
(2) Refer to Figure 76 for sampling circuit details.
(3) LSB means least significant bit.
(4) Measured relative to an ideal full-scale input.
(5) Ensured by simulation.
(6) Calculated on the first nine harmonics of the input frequency.
(7) Indicates signal bandwidth for undersampling applications.
Copyright © 2011, Texas Instruments Incorporated Submit Documentation Feedback 5
Product Folder Link(s): ADS7945 ADS7946