TLS1242 Datasheet, PDF (1/13 Pages) Texas Instruments – CURRENT-MODE PWM CONTROLLER WITH POWER-FACTOR CORRECTOR

D Single-Chip Solution for High-Power-Factor
Switching Power Supply
D Current-Mode PWM Controller
D Fixed-Frequency Average-Current
Power-Factor Corrector (PFC)
Synchronized with PWM Controller
D Full Range ac Operation
D Low Start-Up Current
D Pulse-by-Pulse Current Limiting for PFC
D Undervoltage Lockout with Hysteresis
D Internally Trimmed Bandgap Reference
D External Synchronous Pin
D Overvoltage Protection for PFC
D Upper 8 Pins Configuration Same as
UC3842
TLS1242, TLS1244
CURRENT-MODE PWM CONTROLLER
WITH POWER-FACTOR CORRECTOR
SLVS161 – MAY 1997
N OR DW PACKAGE
(TOP VIEW)
COMP 1
FB 2
ISENS1 3
CT 4
RT 5
GND 6
ISENS2 7
CAO 8
MULT 9
SYNC ¹⁰
20 REF
19 V_CC
18 OUT1
17 PGND
16 OUT2
15 PKLIM
14 IAC
13 RMS
12 AO
11 _VSENSE
description
The TLS1242 and TLS1244 are designed as optimal high-power-factor switching power supply systems with
minimum external components. The current-mode PWM controller and the fixed-frequency average-current
power-factor corrector (PFC) of each device are combined into a 20-pin DIP package. Internally implemented
circuits include: undervoltage lockout (UVLO), featuring a low start-up current; a precision reference that can
be trimmed for accuracy at the error amplifier input; a multiplier; two PWM comparators; overvoltage protection
(OVP); and two totem-pole output stages designed to source or sink current. The output stage is suitable for
driving n-channel MOSFETs, and is low when in the off state.
The fixed-frequency average-current-mode power-factor-correction controller circuit is synchronized with a
current-mode PWM controller internally. Fixed-frequency power-factor correction helps prevent problems in
frequency-sensitive applications such as video monitor, telecom, RF transmitters, and medical imaging. The
synchronization of the PFC with the PWM controller helps reduce EMI problems as well.
The pin assignment of both the TLS1242 and the TLS1244 is intended to accommodate the UC3842/3844 as
well, if PFC is not required in the application. The upper pins (1, 2, 3, 4, 17, 18, 19 and 20) have the same pin
assignment as the UC3842, making the current-mode SPS application more flexible.
The PWM portion of the TLS1242 can operate to duty cycle approaching 100%. A duty cycle range of 0 to 50%
is obtained using the TLS1244.
The TLS1242 and TLS1244 are characterized for operation from 0°C to 70°C.
PRODUCT PREVIEW information concerns products in the formative or
design phase of development. Characteristic data and other
specifications are design goals. Texas Instruments reserves the right to
change or discontinue these products without notice.
Copyright © 1997, Texas Instruments Incorporated
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