Texas Instruments Evaluation Board for LMP8640 LMP8640HV-HEVAL/NOPB LMP8640HV-HEVAL/NOPB 데이터 시트
제품 코드
LMP8640HV-HEVAL/NOPB
V
/
V
Rg
Gain =
k
5
:
+IN
-IN
OUT
V-
V+
RG
-
+
A
-
+
SOURCE
V
DMM1
DMM2
Rsns
+IN
-IN
OUT
V-
V+
RG
-
+
VCC
ohmic
LOAD
LOAD
Rg1
Rg2
VCC
IN
LOAD
Using the Evaluation Board
4
Using the Evaluation Board
4.1
Input and Output Signals
The evaluation board allows you to measure a bidirectional current, so the IN and LOAD banana
connectors can act either as the Source or LOAD pin. If the current flows from the IN pin to the LOAD pin,
a simple way to test the performance of the LMP8640 (LMP8645) is shown in
connectors can act either as the Source or LOAD pin. If the current flows from the IN pin to the LOAD pin,
a simple way to test the performance of the LMP8640 (LMP8645) is shown in
.
Figure 1. LMP8640 (LMP8645) Measurement Setup
The DMM1 is configured as a voltmeter, which measures the output of the LMP8640 (LMP8645), while the
DMM2 is configured as an Ammeter, which measures the current that flows in the LOAD. The source is a
voltage supply that makes sure to set a voltage in the range of -2 V to +46 V for LMP8640 (LMP8645) or -
2 V to +76 V for LMP8640HV (LMP8645HV).
DMM2 is configured as an Ammeter, which measures the current that flows in the LOAD. The source is a
voltage supply that makes sure to set a voltage in the range of -2 V to +46 V for LMP8640 (LMP8645) or -
2 V to +76 V for LMP8640HV (LMP8645HV).
4.2
Gain Selection of LMP8645
The evaluation board is provided with a shunt resistor Rsns (10 m
Ω
, @ 1%, 1W), while two gain resistors
Rg1 and Rg2 (10 k
Ω
, @1%) ensure a gain of 2 V/V for each current sense. The Gain is evaluated
according to formula in
:
(3)
The gain resistor must be chosen such that the max output voltage does not exceed the LMP8645 max
output voltage rating for a given common mode voltage (further details in the Datasheet).
output voltage rating for a given common mode voltage (further details in the Datasheet).
4.3
Single Output
In the applications where a single measurement of a bidirectional current sense is needed is possible to
populate the evaluation board with two amplifiers and some resistors (see
populate the evaluation board with two amplifiers and some resistors (see
For instance, in the following configuration:
R1 = R2 = R3 = R4 = 10 k
Ω
,
R5 = R6 =10 k
Ω
OUT = V
REF
+(OUT
+
-OUT
-
)
V
REF
= 0.5*Vcc_Amp.
3
SNOA546C – November 2009 – Revised April 2013
AN-1975 LMP8640/LMP8645 Evaluation Board
Copyright © 2009–2013, Texas Instruments Incorporated