Texas Instruments AN-1975 LMP8640 User Manual

1

Introduction

This evaluation board shows a bidirectional high-side current sense made using LMP8640 (LMP8645) and
optional differential amplifier in order to have a single output.
2

Connectors

2.1

Power Supply

There are two banana plugs labeled GND and V
plug labeled VCC_Amp is used to power an optional operational amplifier that makes the difference
between the outputs of the two LMP8640 (LMP8645).
2.2

Signal Connectors

There are five connectors for signals.
IN It connects the non inverting input of U1 and inverting input of U2.
LOAD It connects the non inverting input of U2 and inverting input of U1.
The device U1 is able to sense the current when it flows in the shunt resistor from the LOAD pin to the IN
pin. The device U2 is able to sense the current when it flows in the shunt resistor from IN pin to LOAD pin.
OUT+ Output of device U2, the voltage at this pin is related to the current that flows from the IN pin to the LOAD pin.
OUT- Output of device U1, the voltage at this pin is related to the current that flows from the LOAD pin to the IN pin.
OUT Optional Output of the difference amplifier that makes the difference between OUT+ and OUT-
3

Hardware Setup

3.1

Power Supply Setup

• High side current sense LMP8640 (LMP8645)
– Connect a supply voltage in the range between 2.7 V and 12 V to the V
• Optional difference amplifier
– Connect a supply according to the specs of the amplifier to the VCC_Amp and GND turrets.
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SNOA546C – November 2009 – Revised April 2013
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AN-1975 LMP8640/LMP8645 Evaluation Board
Table 1. Input signals
Table 2. Output signals
Copyright © 2009–2013, Texas Instruments Incorporated
SNOA546C – November 2009 – Revised April 2013
to power the evaluation board. Moreover, a banana
CC
AN-1975 LMP8640/LMP8645 Evaluation Board
User's Guide
and GND turrets.
CC
1