TL494 Pulsewidth Modulation Controller
The TL494 possesses all of the functions required to construct a pulse-width-modulation (PWM) control
circuit on a single chip. Designed from the outset for power-supply control, this chip offers the flexibility to tailor the
power-supply control circuitry to a specific application.
The TL494 contains two error amplifiers, an on-chip adjustable oscillator, a dead-time control (DTC) comparator,
a pulse-steering control flip-flop, a 5-V, 5%-precision regulator, and output-control circuits.
The error amplifiers display a common-mode voltage range from –0.3 V to VCC – 2 V. The dead-time control
comparator has a fixed offset that gives approximately 5% dead time. The on-chip oscillator can be bypassed
by terminating RT to the reference output and providing a sawtooth input to CT, or it can drive the common
circuits in synchronous multiple-rail power supplies.
The uncommitted output transistors allow for either common-emitter or emitter-follower output capability. The
TL494 provides for push-pull or single-ended output operation, which can be chosen through the output-control
function. The architecture of this device alleviates the possibility of either output being pulsed twice during
push-pull operation.