PJ494

PJ494 Switchmode Pulse Width Modulation Control Circuit he PJ494 incorporates on a single monolithic chip all the functions required in the construction of a pulsewidth-modulation control circuit. Designed primarily for power supply control, these devices offer the systems engineer the flexibility to tailor the power supply control circuitry to his application. The PJ494 contains an error amplifier, an on-chip adjustable oscillator, a deed-time control comparator, pulse-steering control flip-flop, a 5-volt, 5% precision regulator, and outputcontrol circuits. The error amplifier exhibits a common-mode voltage from –0.3 volts to Vcc –2 volts. The dead-time control comparator has a fixed offset that provides T approximately 5% dead time when externally altered. The onchip oscillatory be bypassed by terminating RT (pin 6) to the reference output and providing a sawtooth input to CT (PIN 5), or it may be used to drive the common circuits in synchronous multiple-rail power supplies. The uncommited output transistor provide either common-emitter or emitterfollower output capability. Each device provides for push-pull or single-ended output operation, which may be selected through the output-control function. The architecture of these devices prohibits the possibility of either output being pulsed twice during push-pull operation. FEATURES Complete PWM Power Control Circuitry Uncommitted Outputs for 200mA Sink or Source Current Output Control Selects Single-Ended or...