6.2 Output Ripple Test
1. Use steps 1 to 6 of
2. Set up the scope as follows:
a. HORIZONTAL SWEEP: 2 μs/div
b. TRIGGER MODE: auto, rising edge
c. TRIGGER SOURCE: Ch1
d. CH1: 50 mV/div, AC coupled, bandwidth 20 MHz
3. Use the tip and barrel technique shown in
to probe VOUT1 and VOUT2 during test procedure.
6.3 Measuring Improved Light Load Efficiency
1. All jumper modifications should be done with no power applied to the EVM
2. SKIPSEL1 and SKIPSEL2 allow the user to select how the EVM operates when in light load.
describes each possible selection.
Table 6-1. SKIPSEL1 or SKIPSEL2 (jumpers JP1 and JP4) Selections
JUMPER LOCATION
MODE
DESCRIPTION
CCM (1 and 2 shorted)
CCM
EVM remains in continuous current mode
AS (3 and 4 shorted) default
Auto-skip
EVM enters auto skip mode at light load, audible noise may
be heard.
OOA_L (5 and 6 shorted)
OOA (< 400 kHz)
EVM enters skip mode with no audible noise
OOA_H (7 and 8 shorted)
OOA (> 400 kHz)
Not recommended
3. Once a mode has been selected, efficiency and regulation measurements may be retaken. Repeat steps 3
to 11 of
. The engineer should reduce the step current when the output is less than 1 A.
shows typical data for the various modes of operation
Test Procedure
SLUU381B – SEPTEMBER 2009 – REVISED FEBRUARY 2022
TPS51220A Buck Controller Evaluation Module User's Guide
9
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