Datasheet

ADS1255
ADS1256
SBAS288K JUNE 2003 REVISED SEPTEMBER 2013
www.ti.com
3
ELECTRICAL CHARACTERISTICS
All specifications at 40°C to +85°C, AVDD = +5V, DVDD = +1.8V, f
CLKIN
= 7.68MHz, PGA = 1, and V
REF
= +2.5V, unless otherwise noted.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Analog Inputs
Full-scale input voltage (AIN
P
AIN
N
) ±2V
REF
/PGA V
Absolute input voltage
Buffer off AGND 0.1 AVDD + 0.1 V
Absolute input voltage
(AIN0-7, AINCOM to AGND)
Buffer on AGND AVDD 2.0 V
Programmable gain amplifier 1 64
Buffer off, PGA = 1, 2, 4, 8, 16 150/PGA kΩ
Differential input impedance
Buffer off, PGA = 32, 64 4.7 kΩ
pp
Buffer on, f
DATA
50Hz
(1)
80 MΩ
SDCS[1:0] = 01 0.5 μA
Sensor detect current sources
SDCS[1:0] = 10 2 μA
SDCS[1:0] = 11 10 μA
System Performance
Resolution 24 Bit
No missing codes All data rates and PGA settings 24 Bit
Data rate (f
DATA
) f
CLKIN
= 7.68MHz 2.5 30,000 SPS
(2)
Integral nonlinearity
Differential input, PGA = 1 ±0.0003 ±0.0010 %FSR
(3)
I
ntegra
l
non
li
near
i
ty
Differential input, PGA = 64 ±0.0007 %FSR
Offset error After calibration On the level of the noise
Offset drift
PGA = 1 ±100 nV/°C
Off
set
d
r
if
t
PGA = 64 ±4 nV/°C
Gain error
After calibration, PGA = 1, Buffer on ±0.005 %
G
a
i
n
error
After calibration, PGA = 64, Buffer on ±0.03 %
Gain drift
PGA = 1 ±0.8 ppm/°C
G
a
i
n
d
r
if
t
PGA = 64 ±0.8 ppm/°C
Common-mode rejection f
CM
(4)
= 60Hz, f
DATA
= 30kSPS
(5)
95 110 dB
Noise See Noise Performance Tables
AVDD power-supply rejection ±5% Δ in AVDD 60 70 dB
DVDD power-supply rejection ±10% Δ in DVDD 100 dB
Voltage Reference Inputs
Reference input voltage (V
REF
) V
REF
VREFP VREFN 0.5 2.5 2.6 V
Negative reference input (VREFN)
Buffer off AGND 0.1 VREFP 0.5 V
N
egat
i
ve
re
f
erence
i
nput
(VREFN)
Buffer on
(6)
AGND VREFP 0.5 V
Positive reference input (VREFP)
Buffer off VREFN + 0.5 AVDD + 0.1 V
P
os
i
t
i
ve
re
f
erence
i
nput
(VREFP)
Buffer on
(6)
VREFN + 0.5 AVDD 2.0 V
Voltage reference impedance f
CLKIN
= 7.68MHz 18.5 kΩ
Digital Input/Output
V
IH
DIN, SCLK, XTAL1/CLKIN,
SYNC/PDWN, CS, RESET
0.8 DVDD 5.25 V
V
IH
D0/CLKOUT, D1, D2, D3 0.8 DVDD DVDD V
V
IL
DGND 0.2 DVDD V
V
OH
I
OH
= 5mA 0.8 DVDD V
V
OL
I
OL
= 5mA 0.2 DVDD V
Input hysteresis 0.5 V
Input leakage 0 < V
DIGITAL
INPUT
< DVDD ±10 μA
Master clock rate
External crystal between XTAL1 and
XTAL2
2 7.68 10 MHz
Master clock rate
External oscillator driving CLKIN 0.1 7.68 10 MHz