Datasheet

Configuration

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5 Configuration

This EVM can be set at a configuration of the user's choice. Please refer to the following specific

configuration setting sections

5.1 Switching Frequency Selection

The switching frequency can be set by the TONSEL pin using JP1 on the EVM. The default setting is

245 kHz for CH1 and 305 kHz for CH2.

Table 2. Switching Frequency Selection

SWITCHING FREQUENCY (kHz)

TONSEL

CONNECTION

CH1 CH2

GND (SLOW) 200 250

VREF (MED1) 245 305

VREG3 (MED2) 300 375

VREG5 (FAST) 365 460

5.2 Operation Mode Selection

Operation mode can be set by the SKIPSEL pin using JP2 on the EVM. The default setting on the EVM is

auto-skip mode.

Table 3. Operation Mode Selection

SKIPSEL CONNECTION OPERATION MODE

GND PWM only

VREF Auto skip

VREG5 Out-of-Audio™

5.3 VCLK ON/OFF Selection

The VCLK drive for the charge-pump can be disabled by pulling down EN0 with 620 kΩ of resistance

using S1 on the EVM.

Table 4. VLCK Control

END CONNECTION VCLK

OPEN ENABLED

Pull down to GND with 620 kΩ DISABLED

6 Physical Layouts

This section provides the board layout and assembly drawings for the EVM, that include the top layer

(Figure 7), the bottom layer (Figure 8), and inner layer views (Figure 9 and Figure 10) of the EVM.

High Performance Synchronous Buck EVM Using the TPS51125A SLUU408–FEBRUARY 2010

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