Test Setup and Procedure
9
SNVU623B – October 2018 – Revised April 2020
Copyright © 2018–2020, Texas Instruments Incorporated
LM5143-Q1 EVM User's Guide
Table 4. EVM Signal Connections
LABEL
DESCRIPTION
VCC
Bias supply connection for the gate drivers
VDDA
Bias supply connection for the analog circuits
DEMB/SYNCIN
Synchronization input
SYNCOUT
Synchronization output
PG1, PG2
Power Good indicators
SS1, SS2
Soft-start/tracking signal inputs
EN1, EN2
ENABLE inputs – tie to GND to disable the respective channel
PGND
Power GND connection
AGND
Analog GND connection
5.2
Test Equipment
Voltage Source:
Use an input voltage source capable of supplying 0–36-V and 12 A.
Multimeters:
•
Voltmeter 1:
Input voltage at VIN+ to VIN–. Set voltmeter to an input impedance of 100 M
Ω
.
•
Voltmeter 2:
Output voltage at VOUT1 to GND. Set voltmeter to an input impedance of 100 M
Ω
.
•
Voltmeter 3:
Output voltage at VOUT2 to GND. Set voltmeter to an input impedance of 100 M
Ω
.
•
Ammeter 1:
Input current. Set ammeter to 1-second aperture time.
•
Ammeter 2:
Output current for channel 1. Set ammeter to 1-second aperture time.
•
Ammeter 2:
Output current for channel 2. Set ammeter to 1-second aperture time.
Electronic Load:
The load must be an electronic constant-resistance (CR) or constant-current (CC) mode
load capable of 0 Adc to 10 Adc at 12 V. For a no-load input current measurement, disconnect the
electronic load as it may draw a small residual current.
Oscilloscope:
With the scope set to 20-MHz bandwidth and AC coupling, measure the output voltage
ripple directly across an output capacitor with a short ground lead normally provided with the scope probe.
Place the oscilloscope probe tip on the positive terminal of the output capacitor, holding the ground barrel
of the probe through the ground lead to the negative terminal of the capacitor. TI does not recommend
using a long-leaded ground connection because this can induce additional noise given a large ground
loop. To measure other waveforms, adjust the oscilloscope as needed.
Safety:
Always use caution when touching any circuits that may be live or energized.
5.3
Recommended Test Setup
5.3.1
Input Connections
•
Prior to connecting the DC input source, set the current limit of the input supply to 0.1 A maximum.
Ensure the input source is initially set to 0 V and connected to the VIN+ and VIN– connection points as
shown in
. An additional input bulk capacitor is recommended to provide damping if long input
lines are used.
•
Connect voltmeter 1 at VIN+ and VIN– connection points to measure the input voltage.
•
Connect ammeter 1 to measure the input current and set to at least 1-second aperture time.
5.3.2
Output Connections
•
Connect electronic loads to VOUT1 and VOUT2 connections. Set the loads to constant-resistance
mode or constant-current mode at 0 A before applying input voltage.
•
Connect voltmeter 2 at VOUT1 and GND connections to measure the output voltage of channel 1.
•
Connect voltmeter 3 at VOUT2 and GND connections to measure the output voltage of channel 2.
•
Connect ammeter 2 and ammeter 3 to measure the output currents.
