Slope Compensation Module

The Slope Compensation (SC) module is designed to provide the necessary slope compensation for fixed frequency, continuous current, current mode switched power supplies. The SC module in a PIC® MCU device works by quickly discharging an internal capacitor at the beginning of each Pulse-Width Modulation (PWM) period of the switching power supply control signal. An internal current sink charges this capacitor at a programmable rate. As the capacitor charges, the capacitor voltage is subtracted from the current reference voltage, producing a linear voltage decay at the required rate.

slopecomp15.png
Block diagram of the SC circuit

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The PIC16F753 is an example of a PIC MCU device with slope compensation included.

The core of the SC module contains the following:

  • on-chip capacitor in series with the voltage source,
  • shorting switch across the capacitor,
  • calibrated current sink, and
  • one-shot pulse generator to ensure the switch is closed long enough to completely discharge the capacitor.

Connections

The input to the SC module can be connected to the following signals:

The output of the SC module can be connected to the follow signals:

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