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The TL494 incorporates all the functions required in the construction of a pulse-width-modulation (PWM) control circuit on a single chip. Designed primarily for power-supply control, this device 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 exhibit a common-mode voltage range from 0.3 V to VCC 2 V. The dead-time control comparator has a fixed offset that provides 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 provide either common-emitter or emitter-follower output capability. The TL494 provides for push-pull or single-ended output operation, which can be selected through the output-control function. The architecture of this device prohibits the possibility of either output being pulsed twice during push-pull operation.
The TL494C is characterized for operation from 0°C to 70°C. The TL494I is characterized for operation from 40°C to 85°C.
TL494CD Maximum Ratings
TL494
UNIT
Supply voltage, VCC (see Note 1)
41
V
Amplifier input voltage, VI
VCC+0.3
V
Collector output voltage, VO
41
V
Collector output current, IO
250
mA
Package thermal impedance qJA (see Notes 2 and 3)
D package
73
°C
N package
88
NS package
64
PW package
108
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds
D, N, or PW package
260
°C
Storage temperature range, Tstg
65 to 150
°C
† Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTES: 1. All voltage values, except differential voltages, are with respect to the network ground terminal. 2. Maximum power dissipation is a function of TJ(max), qJA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD = (TJ(max) TA)/qJA. Operating at the absolute maximum TJ of 150°C can impact reliability. 3. The package thermal impedance is calculated in accordance with JESD 51, except for through-hole packages, which use a trace length of zero.
TL494CD Features
· Complete PWM Power Control Circuitry · Uncommitted Outputs for 200-mA Sink or Source Current · Output Control Selects Single-Ended or Push-Pull Operation · Internal Circuitry Prohibits Double Pulse at Either Output · Variable Dead Time Provides Control Over Total Range · Internal Regulator Provides a Stable 5-V Reference Supply With 5% Tolerance · Circuit Architecture Allows Easy Synchronization