CS3524A

CS3524A Voltage Mode PWM Control Circuit with 200 mA Output Drivers The CS3524A PWM control circuit retains the same versatile architecture of the industry standard CS3524 (SG3524) while adding substantial improvements. The CS3524 is pin−compatible with “non−A” versions, and in most applications can be directly interchanged. The CS3524A, however, eliminates many of the design restrictions which had previously required additional external circuitry. The CS3524A includes a precision 5.0 V reference trimmed to ±1% accuracy (eliminating the need for potentiometer adjustments), an error amplifier with an output voltage swing extending to 5.0 V, and a current sense amplifier useful in either the ground or power supply output lines. The uncommitted 60 V, 200 mA NPN output pair greatly enhances the output drive capability. The CS3524A features an undervoltage lockout circuit which disables all internal circuitry (except the reference) until the input voltage has risen to 8.0 V. This holds standby current low until turn−on, and greatly simplifies the design of low power, off−line supplies. The turn−on circuit has approximately 600 mV of hysteresis for jitter free activation. Other improvements include a PWM latch that insures freedom from multiple pulsing within a period, even in noisy environments; logic to eliminate double pulsing on a single output, a 200 ns external shutdown capability, and automatic thermal protection from excessive chip temperature. The oscillator circuit is us...