LMP8271 Datasheet, PDF (1/5 Pages) National Semiconductor (TI) – High Common Mode, Gain of 20, Bidirectional Precision Voltage Difference Amplifiers

PRELIMINARY
January 2005
LMP8271, LMP8276
High Common Mode, Gain of 20, Bidirectional Precision
Voltage Difference Amplifiers
General Description
The LMP™8271, LMP8276 are fixed gain differential ampli-
fiers with a -2V to 27V input common mode voltage range
and a supply voltage range of 4.5V to 5.5V. The LMP8271,
LMP8276 are precision amplifiers which will detect, amplify
and filter small differential signals in the presence of high
common mode voltages. The gain is fixed at 20 and is
adequate to drive an ADC to full scale in most cases. This
fixed gain is achieved in two separate stages, a pre-amplifier
with gain of +10 and a second stage amplifier with a gain of
+2. The internal signal path is brought out on two pins that
provide a connection for a filter network.
The LMP8271, LMP8276 will function with reduced specifi-
cations over the extended common mode input voltage
range of -5 to 36 Volts. This feature makes the device
suitable for applications with load dump in automotive sys-
tems.
The midrail offset adjustment pin enables the user to utilize
this device for bidirectional current sensing. This is achieved
by adjusting an externally set voltage reference. Accurate
bidirectional load current measurements are achieved when
monitoring the output with respect to this reference voltage
Features
n Bidirectional Current Sense Capability
n Typical Values, TA = 25˚C
n Input Offset Voltage
1mV max
n TCVos (LMP8271)
15µV/˚C max
n TCVos (LMP8276)
30µV/˚C max
n CMRR
80dB Min
n Extended CMVR
-5V to 36V
n Output Voltage Swing
Rail to Rail
n Bandwidth
80KHz
n Operating Temperature Range (Ambient) -40˚C to 125˚C
n Operating Temperature Range (bare die) -40˚C to 150˚C
n Supply Voltage
4.5V to 5.5V
n Supply Current
1mA
Applications
n Fuel Injection Control
n Low Side Driver Configuration Current Sensing
n Power Management Systems
Typical Application
Typical Application: Low side Current Sensing
LMP™ is a trademark of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation DS201308
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