Datasheet

XTR108
3
SBOS187C
www.ti.com
ELECTRICAL CHARACTERISTICS (Cont.)
Boldface limits apply over the specified temperature range, T
A
= –40°C to +85°C.
At T
A
= +25°C, V
PS
= 24V, and Supertex DN2540 external depletion-mode FET transistor, unless otherwise noted, all voltages measured with respect to I
RET
pin.
XTR108EA
PARAMETER CONDITIONS MIN TYP MAX UNITS
PGA (Cont.)
Input Impedance: Differential 30 || 6 GΩ || pF
Input Impedance: Common-Mode 50 || 20 GΩ || pF
Voltage Noise, 0.1Hz to 10Hz 6 µVp-p
PGA Gain
Gain Range Steps 6.25, 12.5, 25, 50, 100, 200, 400 6.25 400 V/V
Initial Error Gain = 6.25, 12.5, 25, 50 ±0.5 ±2.5 %
G = 100, 200 ±0.5 ±3%
G = 400 ±0.8 ±3.5 %
vs Temperature ±30 ppm/°C
Output Voltage Range
(5)
R
LOAD
= 6.34kΩ to I
RET
0.2 4.5 V
Typical Operating Range for 4-20mA XTR Output 0.5 to 2.5 V
Capacitive Drive 200 pF
Short-Circuit Current +6/–9mA
ZERO OFFSET DACS
Zero-Code Output Level V
CM
= 1V, V
IN
= 0V
RTO
(6)
of Current Amplifier R
V/I
= 6.34kΩ 4.116 mA
RTO
(6)
of PGA 522 mV
Coarse DAC, 256 Steps 7 Bits + Sign
Adjustment Range Relative to Zero-Code Level
RTO
(6)
of Current Amplifier –3.77 to +3.77 mA
RTO
(6)
of PGA –470 to +470 mV
Step Size
RTO
(6)
of Current Amplifier 0.029 mA
RTO
(6)
of PGA 3.7 mV
Linearity ±0.5 LSB
Fine DAC, 256 Steps Relative to Zero-Code Level 7 Bits + Sign
Adjustment Range
RTO
(6)
of Current Amplifier –236 to +236 µA
RTO
(6)
of PGA –29.4 to +29.4 mV
Step Size
RTO
(6)
of Current Amplifier 0.0018 mA
RTO
(6)
of PGA 0.23 mV
Linearity ±1LSB
Noise, RTO
(6)
f = 0.1Hz to 10Hz 1.1 µAp-p
CURRENT AMPLIFIER
Current Gain 49 50 51 A/A
Current Gain Drift 10 ppm/°C
CURRENT SOURCES, I
REF1
AND I
REF2
Zero-Code Output Level, Each R
SET
= 12.1kΩ 480 493 510 µA
Coarse DAC, 256 Steps 7 Bits + Sign
Adjustment Range
(7)
–195 to +195 µA
Step Size 1.54 µA
Fine DAC, 256 Steps 7 Bits + Sign
Adjustment Range
(7)
–12.2 to +12.2 µA
Step Size 96 nA
Linearity
Coarse ±0.2 LSB
Fine ±0.5 LSB
vs Temperature ±35 ppm/°C
Matching ±0.2 %
vs Temperature ±10 ppm/°C
Compliance Voltage, Positive
(5)
V
S
– 2V
S
– 1.5 V
Output Impedance 100 MΩ
Current Noise f = 0.1Hz to 10Hz 0.015 µAp-p
LINEARIZATION DAC
Linearization Range, 256 Steps 8 Bits
Max Linearization Coefficient ∆I
REF
/∆V
IN
, R
LIN
= 15.8kΩ 0.99 µA/mV
Step Size 3.9 nA/mV
SUB-REGULATOR, V
S
Supply Voltage for XTR
Voltage 4.8 5.1 5.4 V
vs Temperature ±50 ppm/°C
vs Loop-Supply Voltage V
LOOP
= 7.5V to 24V ±0.03 mV/V