Texas Instruments TL494CN, TL494CJ, TL494CDR, TL494CD, TL494MJB Datasheet

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TL494

PULSE-WIDTH-MODULATION CONTROL CIRCUITS

SLVS074B – JANUARY 1983 – REVISED JULY 1999

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

D, N, NS, OR PW PACKAGE

FEEDBACK

1IN+ 1IN–

DTC

CT RT

GND

(TOP VIEW)

1 2 3 4 5 6 7 8

2IN+

2IN–

15 14

REF

OUTPUT CTRL

Reference Supply With 5% Tolerance

Circuit Architecture Allows Easy Synchronization

description

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.

FUNCTION TABLE

INPUT TO

OUTPUT CTRL

VI = GND Single-ended or parallel output

VI = V

ref

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

OUTPUT FUNCTION

Normal push-pull operation

PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

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TL494 PULSE-WIDTH-MODULATION CONTROL CIRCUITS

SLVS074B – JANUARY 1983 – REVISED JULY 1999

AVAILABLE OPTIONS

PACKAGED DEVICES

0°C to 70°C TL494CD TL494CN TL494CNS TL494CPW TL494Y –40°C to 85°C TL494ID TL494IN — — —

The D, NS, and PW packages are available taped and reeled. Add the suffix R to device type (e.g., TL494CDR). Chip forms are tested at 25°C.

functional block diagram

≈ 0.1 V

DTC

SMALL

OUTLINE

(D)

Oscillator

Dead-Time Control

Comparator

PLASTIC

DIP

(N)

OUTLINE

SMALL

(NS)

SHRINK

SMALL

OUTLINE

(PW)

OUTPUT CTRL

(see Function Table)

CHIP

FORM

(Y)

1IN+ 1IN–

2IN+ 2IN–

FEEDBACK

1 2

16 15

Error Amplifier 1

+ –

Error Amplifier 2

+ –

PWM

Comparator

0.7 mA

Pulse-Steering

Flip-Flop

Reference Regulator

11 10

REF

GND

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Package thermal impedance, θ

(see Notes 2 and 3)

°C

UNIT

Operating free-air temperature, T

°C

TL494

PULSE-WIDTH-MODULATION CONTROL CIRCUITS

SLVS074B – JANUARY 1983 – REVISED JULY 1999

absolute maximum ratings over operating free-air temperature range (unless otherwise noted)

TL494 UNIT

Supply voltage, VCC (see Note 1) 41 V Amplifier input voltage, V Collector output voltage, V Collector output current, I

Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds D, N, or PW package 260 °C Storage temperature range, T

†

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), ambient temperature is PD = (TJ(max) – TA)/

3. The package thermal impedance is calculated in accordance with JESD 51, except for through-hole packages, which use a trace length of zero.

D package 73

stg

, and TA. The maximum allowable power dissipation at any allowable

. Operating at the absolute maximum TJ of 150°C can impact reliability.

N package 88 NS package 64 PW package 108

VCC+0.3 V

41 V

250 mA

–65 to 150 °C

recommended operating conditions

TL494

MIN MAX

Supply voltage, V Amplifier input voltage, V Collector output voltage, V Collector output current (each transistor) 200 mA Current into feedback terminal 0.3 mA Oscillator frequency, f Timing capacitor , C Timing resistor , R

osc

TL494C 0 70 TL494I –40 85

7 40 V

–0.3 VCC–2 V

40 V

1 300 kHz

0.47 10000 nF

1.8 500 kΩ

†

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