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Application Hint:

Temperature drift of the output carrier frequency can be cancelled by measuring both a PWM period and the on-time

of PWM (Duty) at the same time. Since both periods vary in the same direction, computing the ratio between these

values at each PWM period gives consistent measurement of the current feedback over the temperature drift.

Vin+= -260mV

Vs = 0V

Vin+= +260mV

Vs = 0V

Duty=91%

Duty=9%

Carrier Frequency =

130kHz

PO

PO

Timing Waveforms

Figure 1 Output waveform