TEXAS INSTRUMENTS TL494 Technical data

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1
2
3
4
5
6
7
8

16
15
14
13
12
11
10

9

1IN+
1IN−

FEEDBACK

DTC

CT
RT

GND

C1

2IN+
2IN−
REF
OUTPUT CTRL
V

CC

C2
E2
E1

D, DB, N, NS, OR PW PACKAGE

(TOP VIEW)

PULSE-WIDTH-MODULATION CONTROL CIRCUITS

SLVS074E – JANUARY 1983 – REVISED FEBRUARY 2005

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

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 V
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.

– 2 V. The dead-time control

CC

TL494

T

0 ° C to 70 ° C TL494CD TL494CN TL494CNS TL494CDB TL494CPW

–40 ° C to 85 ° C TL494ID TL494IN — — —

(1) The D, DB, NS, and PW packages are available taped and reeled. Add the suffix R to device type (e.g., TL494CDR).

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

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.

A

AVAILABLE OPTIONS

SMALL OUTLINE PLASTIC DIP SMALL OUTLINE

(D) (N) (NS)

PACKAGED DEVICES

(1)

SHRINK SMALL THIN SHRINK

OUTLINE SMALL OUTLINE

(DB) (PW)

Copyright © 1983–2005, Texas Instruments Incorporated

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GND

V

CC

Reference
Regulator

C1

Pulse-Steering

Flip-Flop

C1

1D

DTC

CT

RT

PWM

Comparator

+

−

Error Amplifier 1

≈ 0.1 V

Dead-Time Control

Comparator

Oscillator

OUTPUT CTRL

(see Function Table)

0.7 mA

E1

C2

E2

+

−

Error Amplifier 2

1IN+

1IN−

2IN+

2IN−

FEEDBACK

REF

6
5

4

1
2

16
15

3

13

8

9

11
10

12

14

7

Q1

Q2

≈ 0.7 V

TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS

SLVS074E – JANUARY 1983 – REVISED FEBRUARY 2005

INPUT TO

OUTPUT CTRL

FUNCTION TABLE

OUTPUT FUNCTION

VI= GND Single-ended or parallel output

VI= V

ref

Normal push-pull operation

FUNCTIONAL BLOCK DIAGRAM

2

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PULSE-WIDTH-MODULATION CONTROL CIRCUITS

SLVS074E – JANUARY 1983 – REVISED FEBRUARY 2005

Absolute Maximum Ratings

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

V

CC

V

I

V

O

I

O

θ

JA

Supply voltage
Amplifier input voltage V
Collector output voltage 41 V
Collector output current 250 mA

Package thermal impedance

Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 260 ° C

T

stg

Storage temperature range –65 150 ° C

(1) 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.
(2) All voltages are with respect to the network ground terminal.
(3) Maximum power disipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any allowable ambient

temperatire is PD= (TJ(max) – TA)/ θJA. Operating at the absolute maximum TJof 150 ° C can affect reliability.
(4) The package thermal impedance is calculated in accordance with JESD 51-7.

(2)

(1)

MIN MAX UNIT

CC

D package 73
DB package 82

(3) (4)

N package 67 ° C/W
NS package 64
PW package 108

TL494

41 V

+ 0.3 V

Recommended Operating Conditions

V

CC

V

I

V

O

f

OSC

C

T

R

T

T

A

Supply voltage 7 40 V
Amplifier input voltage –0.3 V
Collector output voltage 40 V
Collector output current (each transistor) 200 mA
Current into feedback terminal 0.3 mA
Oscillator frequency 1 300 kHz
Timing capacitor 0.47 10000 nF
Timing resistor 1.8 500 k Ω

Operating free-air temperature ° C

MIN MAX UNIT

TL494C 0 70
TL494I –40 85

CC

– 2 V

3

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 



N

n1

(xn X)

2

N  1



TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS

SLVS074E – JANUARY 1983 – REVISED FEBRUARY 2005

Electrical Characteristics

over recommended operating free-air temperature range, V

Reference Section

PARAMETER TEST CONDITIONS

Output voltage (REF) IO= 1 mA 4.75 5 5.25 V
Input regulation V
Output regulation IO= 1 mA to 10 mA 1 15 mV
Output voltage change with temperature ∆ TA= MIN to MAX 2 10 mV/V
Short-circuit output current

(1) For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.
(2) All typical values, except for parameter changes with temperature, are at TA= 25 ° C.
(3) Duration of short circuit should not exceed one second.

(3)

Oscillator Section

CT= 0.01 µ F, RT= 12 k Ω (see Figure 1 )

PARAMETER TEST CONDITIONS

Frequency 10 kHz
Standard deviation of frequency
Frequency change with voltage V
Frequency change with temperature

(1) For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.
(2) All typical values, except for parameter changes with temperature, are at TA= 25 ° C.
(3) Standard deviation is a measure of the statistical distribution about the mean as derived from the formula:

(3)

(4)

All values of VCC, CT, RT, and TAconstant 100 Hz/kHz

= 7 V to 40 V, TA= 25 ° C 1 Hz/kHz

CC

∆ TA= MIN to MAX 10 Hz/kHz

= 15 V, f = 10 kHz (unless otherwise noted)

CC

(1)

= 7 V to 40 V 2 25 mV

CC

REF = 0 V 25 mA

(1)

TL494C, TL494I

MIN TYP

TL494C, TL494I

MIN TYP

(2)

MAX

(2)

MAX

UNIT

UNIT

(4) Temperature coefficient of timing capacitor and timing resistor are not taken into account.

Error-Amplifier Section

See Figure 2

V

–0.3 to

CC

TL494C, TL494I

MIN TYP

– 2

(1)

MAX

PARAMETER TEST CONDITIONS UNIT

Input offset voltage VO(FEEDBACK) = 2.5 V 2 10 mV
Input offset current VO(FEEDBACK) = 2.5 V 25 250 nA
Input bias current VO(FEEDBACK) = 2.5 V 0.2 1 µ A

Common-mode input voltage range V
Open-loop voltage amplification ∆ VO= 3 V, VO= 0.5 V to 3.5 V, RL= 2 k Ω 70 95 dB

Unity-gain bandwidth VO= 0.5 V to 3.5 V, RL= 2 k Ω 800 kHz
Common-mode rejection ratio ∆ VO= 40 V, TA= 25 ° C 65 80 dB
Output sink current (FEEDBACK) VID= –15 mV to –5 V, V (FEEDBACK) = 0.7 V 0.3 0.7 mA
Output source current (FEEDBACK) VID= 15 mV to 5 V, V (FEEDBACK) = 3.5 V –2 mA

(1) All typical values, except for parameter changes with temperature, are at TA= 25 ° C.

4

= 7 V to 40 V V

CC

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PULSE-WIDTH-MODULATION CONTROL CIRCUITS

SLVS074E – JANUARY 1983 – REVISED FEBRUARY 2005

Electrical Characteristics

over recommended operating free-air temperature range, V

Output Section

PARAMETER TEST CONDITIONS MIN TYP

Collector off-state current V
Emitter off-state current V

Collector-emitter saturation voltage V

Output control input current VI= V

(1) All typical values, except for temperature coefficient, are at TA= 25 ° C.

Common emitter VE= 0, IC= 200 mA 1.1 1.3
Emitter follower V

= 40 V, V

CE

= VC= 40 V, VE= 0 –100 µ A

CC

O(C1 or C2)

Dead-Time Control Section

See Figure 1

PARAMETER TEST CONDITIONS MIN TYP

Input bias current (DEAD-TIME CTRL) VI= 0 to 5.25 V –2 –10 µ A
Maximum duty cycle, each output 45 %

Input threshold voltage (DEAD-TIME CTRL) V

(1) All typical values, except for temperature coefficient, are at TA= 25 ° C.

VI(DEAD-TIME CTRL) = 0, CT= 0.01 µ F,
RT= 12 k Ω

Zero duty cycle 3 3.3
Maximum duty cycle 0

= 15 V, f = 10 kHz (unless otherwise noted)

CC

= 40 V 2 100 µ A

CC

= 15 V, IE= –200 mA 1.5 2.5

ref

(1)

MAX UNIT

3.5 mA

(1)

MAX UNIT

TL494

PWM Comparator Section

See Figure 1

PARAMETER TEST CONDITIONS MIN TYP

Input threshold voltage (FEEDBACK) Zero duty cyle 4 4.5 V
Input sink current (FEEDBACK) V (FEEDBACK) = 0.7 V 0.3 0.7 mA

(1) All typical values, except for temperature coefficient, are at TA= 25 ° C.

(1)

MAX UNIT

Total Device

PARAMETER TEST CONDITIONS MIN TYP

V

= 15 V 6 10

Standby supply current mA

Average supply current VI(DEAD-TIME CTRL) = 2 V, See Figure 1 7.5 mA

(1) All typical values, except for temperature coefficient, are at TA= 25 ° C.

RT= V
All other inputs and outputs open

,

ref

CC

V

= 40 V 9 15

CC

(1)

MAX UNIT

Switching Characteristics

TA= 25 ° C

PARAMETER TEST CONDITIONS MIN TYP

Rise time 100 200 ns
Fall time 25 100 ns
Rise time 100 200 ns
Fall time 40 100 ns

Common-emitter configuration, See Figure 3

Emitter-follower configuration, See Figure 4

(1)

MAX UNIT

(1) All typical values, except for temperature coefficient, are at TA= 25 ° C.

5

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Test

Inputs

DTC
FEEDBACK

RT
CT

GND

50 kΩ

12 kΩ

0.01 µF

V

CC

REF

OUTPUT
CTRL

E2

C2

E1

C1

Output 1

Output 2

150 Ω
2 W

150 Ω
2 W

VCC = 15 V

TEST CIRCUIT

1IN+

V

CC

V

CC

0 V

0 V

Voltage

at C1

Voltage

at C2

Voltage

at CT

DTC

FEEDBACK

0 V

0.7 V
0%

MAX

0%

Threshold Voltage

Threshold Voltage

VOLTAGE WA VEFORMS

Duty Cycle

Error
Amplifiers

7

14

12

8
9

11

10

4
3

6

5

1
2
16
15

13

1IN−

2IN−

2IN+

TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS

SLVS074E – JANUARY 1983 – REVISED FEBRUARY 2005

PARAMETER MEASUREMENT INFORMATION

6

Figure 1. Operational Test Circuit and Waveforms