SBAS418I – SEPTEMBER 2007 – REVISED MARCH 2015
5.2 Electrical Characteristics
Limit specifications at –40°C to +85°C. Typical specifications at +25°C, AVDD = +2.5V, AVSS = –2.5V, f
CLK
(1)
= 4.096MHz,
VREFP = +2.5V, VREFN = –2.5V, DVDD = +3.3V, CAPN – CAPP = 10nF, PGA = 1, and f
DATA
= 1000SPS, unless otherwise
noted.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
ANALOG INPUTS
Full-scale input voltage
V
IN
= (AINP – AINN)
±V
REF
/(2 × PGA)
V
Absolute input range
AINP or AINN
AVSS + 0.7
AVDD – 1.25
V
PGA input voltage noise density
5
nV/
√
Hz
Chop on
1
G
Ω
Differential input impedance
Chop off
100
G
Ω
Common-mode input impedance
100
M
Ω
Input bias current
1
nA
Crosstalk
f = 31.25Hz
–135
dB
MUX on-resistance
30
Ω
PGA OUTPUT (CAPP, CAPN)
Absolute output range
AVSS + 0.4
AVDD – 0.4
V
PGA differential output impedance
600
Ω
Output impedance tolerance
±10%
External bypass capacitance
10
100
nF
Modulator differential input impedance
55
k
Ω
AC PERFORMANCE
Signal-to-noise ratio
(2)
SNR
120
124
dB
PGA = 1...16
–122
–114
Total harmonic distortion
(3)
THD
PGA = 32
–117
–110
dB
PGA = 64
–115
Spurious-free dynamic
dB
SFDR
123
range
DC PERFORMANCE
Resolution
No missing codes
31
Bits
FIR filter mode
250
4000
SPS
Data rate
f
DATA
Sinc filter mode
8000
128,000
SPS
Integral nonlinearity (INL)
(4)
Differential input
0.00005
0.0004
% FSR
(5)
Offset error
50
200
μ
V
Offset error after calibration
(6)
Shorted input
1
μ
V
Offset drift
0.02
μ
V/°C
Gain error
(7)
–1.5%
–1.0%
–0.5%
Gain error after calibration
(6)
0.0002%
PGA = 1
2
ppm/°C
Gain drift
PGA = 16
9
ppm/°C
Gain matching
(8)
0.3%
0.8%
Common-mode rejection
f
CM
= 60Hz
(9)
95
110
dB
AVDD, AVSS
80
90
Power-supply rejection
f
PS
= 60Hz
(9)
dB
DVDD
90
115
(1)
f
CLK
= system clock.
(2)
V
IN
= 20mV
DC
/PGA; see
(3)
V
IN
= 31.25Hz, –0.5dBFS.
(4)
Best-fit method.
(5)
FSR: Full-scale range = ±V
REF
/(2 × PGA).
(6)
Calibration accuracy is on the level of noise reduced by 4 (calibration averages 16 readings).
(7)
The PGA output impedance and the modulator input impedance results in –1% systematic gain error.
(8)
Gain match relative to PGA = 1.
(9)
f
CM
is the input common-mode frequency. f
PS
is the power-supply frequency.
Copyright © 2007–2015, Texas Instruments Incorporated
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