Test Setup and Procedure
7
SNVU592D – July 2018 – Revised April 2020
Copyright © 2018–2020, Texas Instruments Incorporated
LM5180-Q1 Single-Output EVM User's Guide
5.2
Test Equipment
Voltage Source:
The input voltage source V
IN
must be a 0–65-V variable DC source capable of supplying
0.5 A.
Multimeters:
•
Voltmeter 1:
Input voltage at VIN+ to VIN–. Set the voltmeter to an input impedance of 100 M
Ω
.
•
Voltmeter 2:
Output voltage at VOUT+ to VOUT–. Set the voltmeter to an input impedance of 100 M
Ω
.
•
Ammeter 1:
Input current. Set the ammeter to 1-second aperture time.
•
Ammeter 2:
Output current. Set the 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 1 Adc at 5 V. For a no-load input current measurement, disconnect the electronic
load as it can 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 an electronic load to VOUT+ and VOUT– connections. Set the load to constant-resistance
mode or constant-current mode at 0 A before applying input voltage.
•
Connect voltmeter 2 at VOUT+ and VOUT– connection points to measure the output voltage.
•
Connect ammeter 2 to measure the output current.
5.4
Test Procedure
5.4.1
Line and Load Regulation, Efficiency
•
Set up the EVM as described above.
•
Set load to constant resistance or constant current mode and to sink 10 mA.
•
Increase input source from 0 V to 24 V; use voltmeter 1 to measure the input voltage.
•
Increase the current limit of the input supply to 0.5 A.
•
Using voltmeter 2 to measure the output voltage, V
OUT
, vary the load current from 10 mA to 1 A DC;
V
OUT
should remain within the load regulation specification.
•
Set the load current to 0.5 A (50% rated load) and vary the input source voltage from 10 V to 65 V;
V
OUT
must remain within the line regulation specification.
•
Decrease load to 0 A. Decrease input source voltage to 0 V.
