2.3.2 PS Pin Configuration and Switching Frequency Setting:

In parallel operation, the PS pin is used to define both the switching-frequency and phase configuration. For this design, the Host module PS setting determines the switching frequency, while the Client module PS setting defines its phase relationship with respect to the Host device for interleaved operation.

  • U1 Host: PS (pin 11) connected to GND through R23 = 0Ω
  • U2 Client: PS (pin 11) connected to GND through R37 = 1.13 kΩ

This configuration sets the Client module to 180° phase shift relative to the Host module, as required for two-module interleaving. The aforementioned PS pin configuration sets the switching frequency per phase to 625 kHz and the output voltage to 0.8V.

Alternate phase and switching-frequency settings may be selected per Tables 2-3 (PS Resistor Values and Functions) and 2-4 (Switching Frequencies and Output Voltages) of the MCPF1525M06 datasheet.

Note:

When the PS pin resistor is set to 0Ω, the switching frequency is selected based on the configured output-voltage range. After setting the VOUT_COMMAND to desired output voltage, cycle the EN signal low and then high to reinitialize the device and apply the correct switching-frequency setting as defined in Table 2-4 (Switching Frequencies and Output Voltages) of the MCPF1525M06 datasheet.

If a hardware feedback resistor divider is used, include the divider gain when calculating the required VOUT_COMMAND, since the command sets the FB regulation voltage and not VOUT directly.