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Test Procedure

6.2 Output Ripple Test

1. Use steps 1 to 6 of section Section 6.1 to start output.

2. Set up the scope as follows:

(a) HORIZONTAL SWEEP: 2 μs/div.

(b) TRIGGER MODE: auto, rising edge

(d) CH1: 50 mV/div, AC coupled, bandwidth 20 MHz

3. Use “Tip & Barrel” technique shown in Figure 3 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. Table 3

describes each possible selection.

Table 3. SKIPSEL1 or SKIPSEL2 (jumpers JP1 and JP4) Selections

JUMPER LOCATION MODE DESCRIPTION

CCM (1 and 2 shorted) CCM EVM remains in continuous current mode

EVM enters auto skip mode at light load, audible noise

AS (3 and 4 shorted) default Auto-skip

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 section Section 6.1. The engineer should reduce the step current when the output is

less than 1 A. Section 7 shows typical data for the various modes of operation

SLUU381A–September 2009–Revised May 2011 High Performance Dual Output Synchronous Buck EVM

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