Slope Compensation Module Example

Last modified by Microchip on 2023/11/09 09:03

Using a PIC16F753 in a simple boost converter circuit, the SLPCCON0 and SLCCON1 registers need to be set up to use the Slope Compensation (SC) module.

Slope compensation schematic

The SC module is enabled by setting the SCxEN bit to 1.

The SC module will react to the falling threshold signal from the output of the Operational Amplifier (op amp) so the SCxPOL bit is set to 0.

The output connection of the SC module is connected to the Comparator 1 input so the SCxTSS bits are set to 10h.

The input connection to the SC module is the output of the op amp, which is the same as the SLPC1IN selection so the SCxINS bit is set to 0.

When the circuit is using an R3 value of 1Ω for current sense resistor and the peak current is 1A, then the peak current expressed as a voltage (VREF) is 1V. If the PWM signal is running at 1 MHz, then the period is 1 µs. Therefore, the desired slope is 0.5V/µs as seen in the accompanying equation.

Slope compensation equation

According to the SCxISET bits chart, 0.5 V/µs correlates directly to the SCxISET value of 6h, so that value is stored in the SCxISET bits of the SLPCCON1 register. Since this is a direct correlation we can set the range setting to SCxRNG = 0.