LMP8601 Evaluation Board
User's Manual
National Semiconductor
Application Note 1940
BeB Hennink
February 6, 2009
Introduction
The LMP8601 Current Sense evaluation Board is designed
to evaluate the LMP8601, 60V Common Mode, Bidirectional
Precision Current Sensing Amplifier. This board has a
LMP8601 part mounted on the PCB together with the required
de-coupling capacitor, power supply connections, Input and
Output connectors and a 3 pin header for connecting the off-
set pin to either GND or V
S
.
30089701
FIGURE 1. The LMP8601 Evaluation Board
General Description
The LMP8601 and LMP8601Q are fixed 20x gain precision
amplifiers. The part amplifies and filters small differential sig-
nals in the presence of high common mode voltages. The
input common mode voltage range is −22V to +60V when
operating from a single 5V supply. With 3.3V supply, the input
common mode voltage range is from −4V to +27V. The
LMP8601 and LMP8601Q are members of the Linear Mono-
litic Precision (LMP
®
) family and are ideal parts for unidirec-
tional and bidirectional current sensing applications. All
parameter values of the part that are shown in the tables of
the LMP8601 data sheet are 100% tested and all bold values
are also 100% tested over temperature.
The part has a precise gain of 20x which is adequate in most
targeted applications to drive an ADC to its full scale value.
The fixed gain is achieved in two separate stages, a pream-
plifier with a gain of 10x and an output stage buffer amplifier
with a gain of 2x. The connection between the two stages of
the signal path is brought out on two pins to enable the pos-
sibility to create an additional filter network around the output
buffer amplifier. These pins can also be used for alternative
configurations with different gain as described in the applica-
tions section of the data sheet .
The mid-rail offset adjustment pin enables the user to use
these devices for bidirectional single supply voltage current
sensing. The output signal is bidirectional and mid-rail refer-
enced when this pin is connected to the positive supply rail.
With the offset pin connected to ground, the output signal is
unidirectional and ground-referenced .
The LMP8601Q incorporates enhanced manufacturing and
support processes for the automotive market, including defect
detection methodologies. Reliability qualification is compliant
with the requirements and temperature grades defined in the
AEC Q100 standard
LMP8601 Operating Conditions
•
Temperature Range
−40°C to 125°C
•
Power Supply Voltage
3.0V
≤
V
S
≤
5.5V
•
CMVR at V
S
= 3.3V
−4V to 27V
•
CMVR at V
S
= 5.0V
−22V to 60V
© 2009 National Semiconductor Corporation
300897
www.national.com
LMP8601 Evaluation Board User's Manual
AN-1940