Slope Compensation Module Example

Using a PIC16F753 in a simple boost converter circuit, the SLPCCON0 and SLCCON1 registers need to be setup to use the slope compensation.


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

The SC module will react to the a falling threshold signal from the output of the 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 10.

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 1 ohm for current sense resistor and the peak current is 1 amp, then the peak current expressed as a voltage (VREF) is 1 volt. If the PWM signal is running at 1 MHz, then the period is 1 microsecond. Therefore, the desired slope is 0.5 Volts / microsecond as seen in the equation below:


According to the SCxISET bits chart, the 0.5v/usec correlates directly to the SCxISET value of 6 hex, 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.

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