The VC terminal is switched to ground by the internal totem-pole source transistors on alternate oscillator cycles. In the design, driver outputs of the chip are grounded. 10K Trimpot RP2 is for duty cycle adjustment. Tinkerers should note that recommended value for CT is from 1n to 100n, and RT is 2K-150K. Important pins of the chip (as used here) is: Pin No.Īnd here, the oscillator frequency is: 1/CT(0.7xRT) ie. Latching PWM to prevent multiple pulses.Using the nifty SG3525 chip as the key component offers more flexibility and reliability because it has the following features: Operating voltage of the internal circuit is 9V DC by default but you can use DC supply inputs in other ranges without major alterations (refer official datasheet of the chip). Duty cycle of the PWM of this basic design (shown next) can be adjusted from 0 to 100% (+/- 5%), and the frequency scale is in KHz. Stand-alone PWM power driver presented here is, in fact, a high-current pulse width modulator designed around SG3525A/KA3525A to drive beefy brushed DC motors and/or powerful light emitting diodes. Why it’s time I fell love again with the nostalgic regulating pulse width modulating chip? Still, it’s available from many web-shops, and surprisingly it can be used as a poor man’s alternative to a tiny micro controller in a few fortunate situations! The SG3525A is a pulse width modulator integrated circuit designed to offer improved performance and lowered external parts count when used in designing all types of switching power supplies. Do you remember the feeling of building your own power electronics projects with a nifty analog chip? Something like DC-AC power inverter based on the SG3525?
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