TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS
SLVS074C – JANUARY 1983 – REVISED DECEMBER 2001
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
D
Complete PWM Power Control Circuitry
D
Uncommitted Outputs for 200-mA Sink or
Source Current
D
Output Control Selects Single-Ended or
Push-Pull Operation
D
Internal Circuitry Prohibits Double Pulse at
Either Output
D
Variable Dead Time Provides Control Over
Total Range
D
Internal Regulator Provides a Stable 5-V
Reference Supply With 5% Tolerance
D
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 OUTPUT FUNCTION
VI = GND Single-ended or parallel output
VI = Vref Normal push-pull operation
Copyright 2001, Texas Instruments Incorporated
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.
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.
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
VCC
C2
E2
E1
D, N, NS, OR PW PACKAGE
(TOP VIEW)
TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS
SLVS074C – JANUARY 1983 – REVISED DECEMBER 2001
2POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
AVAILABLE OPTIONS
PACKAGED DEVICES
TASMALL
OUTLINE
(D)
PLASTIC
DIP
(N)
SMALL
OUTLINE
(NS)
SHRINK
SMALL
OUTLINE
(PW)
0°C to 70°C TL494CD TL494CN TL494CNS TL494CPW
–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).
functional block diagram
GND
VCC
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
TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS
SLVS074C – JANUARY 1983 – REVISED DECEMBER 2001
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)†
Supply voltage, VCC (see Note 1) 41 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Amplifier input voltage, VI V
CC + 0.3 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Collector output voltage, VO 41 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Collector output current, IO 250 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Package thermal impedance, θJA (see Note 2 and 3): D package 73°C/W. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
N package 67°C/W. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
NS package 64°C/W. . . . . . . . . . . . . . . . . . . . . . . . . . . .
PW package 108°C/W. . . . . . . . . . . . . . . . . . . . . . . . . .
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 260°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, Tstg –65°C 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 af fect device reliability.
NOTES: 1. All voltage values are with respect to the network ground terminal.
2. Maximum power dissipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any allowable
ambient temperature is PD = (TJ(max) – TA)/θJA. Operating at the absolute maximum TJ of 150°C can impact reliability.
3. The package thermal impedance is calculated in accordance with JESD 51-7.
recommended operating conditions
MIN MAX UNIT
VCC Supply voltage 7 40 V
VIAmplifier input voltage –0.3 VCC–2 V
VOCollector output voltage 40 V
Collector output current (each transistor) 200 mA
Current into feedback terminal 0.3 mA
fosc Oscillator frequency 1 300 kHz
CTT iming capacitor 0.47 10000 nF
RTTiming resistor 1.8 500 kΩ
TA
O
p
erating free-air tem
p
erature
TL494C 0 70 °
C
TA
O erating
free
-
air
tem erature
TL494I –40 85
°C
TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS
SLVS074C – JANUARY 1983 – REVISED DECEMBER 2001
4POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
electrical characteristics over recommended operating free-air temperature range, VCC = 15 V,
f = 10 kHz (unless otherwise noted)
reference section
PARAMETER
TEST CONDITIONS†
TL494C, TL494I
UNIT
PARAMETER
TEST
CONDITIONS†
MIN TYP‡MAX
UNIT
Output voltage (REF) IO = 1 mA 4.75 5 5.25 V
Input regulation VCC = 7 V to 40 V 2 25 mV
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§REF = 0 V 25 mA
†For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.
‡All typical values, except for parameter changes with temperature, are at TA = 25°C.
§Duration of the short circuit should not exceed one second.
oscillator section, CT = 0.01 µF, RT = 12 kΩ (see Figure 1)
PARAMETER
TEST CONDITIONS†
TL494, TL494I
UNIT
PARAMETER
TEST
CONDITIONS†
MIN TYP‡MAX
UNIT
Frequency 10 kHz
Standard deviation of frequencyAll values of VCC, CT, RT, and TA constant 100 Hz/kHz
Frequency change with voltage VCC = 7 V to 40 V, TA = 25°C 1 Hz/kHz
Frequency change with temperature#∆TA = MIN to MAX 10 Hz/kHz
†For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.
‡All typical values, except for parameter changes with temperature, are at TA = 25°C.
Standard deviation is a measure of the statistical distribution about the mean as derived from the formula:
s
+
ȍ
N
n
+
1(xn
*
X)2
N
*
1
Ǹ
#Temperature coef ficient of timing capacitor and timing resistor are not taken into account.
error-amplifier section (see Figure 2)
TEST CONDITIONS
TL494, TL494I
UNIT
TEST
CONDITIONS
MIN TYP‡MAX
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 µA
Common-mode input voltage range VCC = 7 V to 40 V –0.3 to
VCC–2V
Open-loop voltage amplification ∆VO = 3 V, RL = 2 kΩ, VO = 0.5 V to 3.5 V 70 95 dB
Unity-gain bandwidth VO = 0.5 V to 3.5 V, RL = 2 kΩ800 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
‡All typical values, except for parameter changes with temperature, are at TA = 25°C.
TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS
SLVS074C – JANUARY 1983 – REVISED DECEMBER 2001
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
electrical characteristics over recommended operating free-air temperature range, VCC = 15 V,
f = 10 kHz (unless otherwise noted)
output section
PARAMETER TEST CONDITIONS MIN TYP†MAX UNIT
Collector off-state current VCE = 40 V, VCC = 40 V 2 100 µA
Emitter off-state current VCC = VC = 40 V, VE = 0 –100 µA
Common emitter VE = 0, IC = 200 mA 1.1 1.3
V
-
Emitter follower VO(C1 or C2) = 15 V, IE = –200 mA 1.5 2.5
V
Output control input current VI = Vref 3.5 mA
†All typical values except for temperature coefficient are at TA = 25°C.
dead-time control section (see Figure 1)
PARAMETER TEST CONDITIONS MIN TYP†MAX UNIT
Input bias current (DEAD-TIME CTRL) VI = 0 to 5.25 V –2–10 µA
Maximum duty cycle, each output VI (DEAD-TIME CTRL) = 0, CT = 0.01 µF, RT = 12 kΩ45%
In
p
ut threshold voltage (DEAD TIME CTRL)
Zero duty cycle 3 3.3
V
Input
threshold
voltage
(DEAD
-
TIME
CTRL)
Maximum duty cycle 0
V
†All typical values except for temperature coefficient are at TA = 25°C.
PWM comparator section (see Figure 1)
PARAMETER TEST CONDITIONS MIN TYP†MAX UNIT
Input threshold voltage (FEEDBACK) Zero duty cycle 4 4.5 V
Input sink current (FEEDBACK) V (FEEDBACK) = 0.7 V 0.3 0.7 mA
†All typical values except for temperature coefficient are at TA = 25°C.
total device
PARAMETER TEST CONDITIONS MIN TYP†MAX UNIT
Standby su
pp
ly current
RT=V f
All other in
p
uts and out
p
uts o
p
en
VCC = 15 V 6 10
mA
Standby
supply
current
RT
=
V
ref,
All
other
inputs
and
outputs
open
VCC = 40 V 9 15
mA
Average supply current VI (DEAD-TIME CTRL) = 2 V, See Figure 1 7.5 mA
†All typical values except for temperature coefficient are at TA = 25°C.
switching characteristics, TA = 25°C
PARAMETER TEST CONDITIONS MIN TYP†MAX UNIT
Rise time
Common emitter configuration
See Figure 3
100 200 ns
Fall time
Common
-
emitter
configuration
,
See
Figure
3
25 100 ns
Rise time
Emitter follower configuration
See Figure 4
100 200 ns
Fall time
Emitter
-
follower
configuration
,
See
Figure
4
40 100 ns
†All typical values except for temperature coefficient are at TA = 25°C.
TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS
SLVS074C – JANUARY 1983 – REVISED DECEMBER 2001
6POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
Test
Inputs DTC
FEEDBACK
RT
CT
GND
50 kΩ
12 kΩ
0.01 µF
VCC
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+
VCC
VCC
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 WAVEFORMS
Duty Cycle
Error
Amplifiers
7
14
12
8
9
11
10
4
3
6
5
1
2
16
15
13
1IN–
2IN–
2IN+
Figure 1. Operational Test Circuit and Waveforms
TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS
SLVS074C – JANUARY 1983 – REVISED DECEMBER 2001
7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
+
–
+
–
VI
Vref
FEEDBACK
Amplifier Under Test
Other Amplifier
Figure 2. Amplifier Characteristics
Output
Each Output
Circuit
68 Ω
2 W
15 V
CL = 15 pF
(See Note A)
90%
10%
90%
10%
tftr
TEST CIRCUIT OUTPUT VOLTAGE WAVEFORM
NOTE A: CL includes probe and jig capacitance.
Figure 3. Common-Emitter Configuration
Output
Each Output
Circuit
68 Ω
2 W
15 V
CL = 15 pF
(See Note A)
90%
10%
90%
10%
tf
tr
TEST CIRCUIT OUTPUT VOLTAGE WAVEFORM
NOTE A: CL includes probe and jig capacitance.
Figure 4. Emitter-Follower Configuration
TL494
PULSE-WIDTH-MODULATION CONTROL CIRCUITS
SLVS074C – JANUARY 1983 – REVISED DECEMBER 2001
8POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TYPICAL CHARACTERISTICS
Df = 1%
†
40
10
100
1 k 4 k 10 k 40 k 100 k 400 k 1 M
f – Oscillator Frequency and Frequency Variation – Hz
OSCILLATOR FREQUENCY AND
FREQUENCY VARIATION†
vs
TIMING RESISTANCE
400
1 k
4 k
10 k
40 k
100 k
RT – Timing Resistance – Ω
0.1 µF
–2% –1%
0% 0.01 µF
0.001 µF
VCC = 15 V
TA = 25°C
CT = 1 µF
†Frequency variation (∆f) is the change in oscillator frequency that occurs over the full temperature range.
Figure 5
10
0
100
20
1 10 100 1 M
A – Amplifier V oltage Amplification – dB
30
f – Frequency – Hz
AMPLIFIER VOLTAGE AMPLIFICATION
vs
FREQUENCY
1 k
VCC = 15 V
∆VO = 3 V
TA = 25°C
10 k
40
50
60
70
80
90
100 k
Figure 6
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Copyright 2001, Texas Instruments Incorporated