TL494 Datasheet, PDF (1/6 Pages) Motorola, Inc – SWITCHMODE PULSE WIDTH MODULATION CONTROL CIRCUIT

Pulse-Width-Modulation Control Circuits
TL494
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,5%
● Circuit Architecture Allows Easy Synchronization
Error
AMP 1
NONINV
INPUT
INV INPUT
FEEDBACK
DEAD-TIME
CONTROL
CT
RT
GND
C1
SOP16/DIP16
(TOP VIEW)
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
NONINV
INPUT
INV INPUT
Error
AMP 2
REF OUT
OUTPUT
CONTROL
Vcc
C2
E2
E1
DESCRIPTION
The TL494 incorporate on a single monolithic chip all the functions
required in the construction of a pulse-width-modulation control,
these devices offer the systems engineer the flexibility to tailor
ORDERING INFORMATION
the power supply control circuitry to his application.
Device
Package
The TL494 contains an error amplifier, an on-chip adjustable
TL494D
16 SOP
oscillator, a dead-time control comparator, pulse-steering control
TL494N
18 DIP
flip-flop, a 5-volt, 5% precision regulator, and output-control circuit.
The error amplifier exhibits a common-mode voltage range from -0.3 volts to Vcc -2 volts. The dead-time control
comparator has a fixed offset that provides approximately 5% dead time when externally altered. The on-chip
oscillator may be bypassed by terminating R_T (pin 6) to the reference output and providing a sawtooth in put to
CT (pin 5), or it may be used to drive the common circuits in synchronous multiple-rail power supplies. The
uncommited output transistors provide either common-emitter or emitter-follower output capability. Each Device
provides for push-pull or single-ended output operation, which may be selected through the output-control funct
-ion. The architecture of these devices prohibits the possibility of either output being pulsed twice during push
-pull operation.
Functional Block Diagram
R_T
C_T
DEAD
TIME
CONTROL
0.1V
OSCILLATOR
DEAD-TIME CONTROL COMPARATOR
NONINVERTING INPUT
INVERTING INPUT
ERROR AMPLIFIER
+
1
-
NONINVERTING INPUT
INVERTING INPUT
ERROR AMPLIFIER
+
2
-
PWM COMPARATOR
FEEDBACK
OUTPUT CONTROL
C1
PULSE-STEERING FLIP-FLOP
REFERENCE
Q1
C1
E1
Q2
C2
E2
Vcc
Vref
GND
Mar. 2006-Rev06
145
HTC