TL284X_07 Datasheet, PDF (1/18 Pages) Texas Instruments – CURRENT-MODE PWM CONTROLLERS

TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
D Optimized for Off-Line and dc-to-dc
Converters
D Low Start-Up Current (<1 mA)
D Automatic Feed-Forward Compensation
D Pulse-by-Pulse Current Limiting
D Enhanced Load-Response Characteristics
D Undervoltage Lockout With Hysteresis
D Double-Pulse Suppression
D High-Current Totem-Pole Output
D Internally Trimmed Bandgap Reference
D 500-kHz Operation
D Error Amplifier With Low Output
Resistance
D Designed to Be Interchangeable With
UC2842 and UC3842 Series
description/ordering information
SLVS038F – JANUARY 1989 – REVISED FEBRUARY 2003
D PACKAGE
(TOP VIEW)
COMP 1
NC 2
VFB 3
NC 4
ISENSE 5
NC 6
RT/CT ⁷
14 REF
13 NC
12 V_CC
11 VC
10 OUTPUT
9 GND
8 POWER GROUND
NC – No internal connection
D-8 OR P PACKAGE
(TOP VIEW)
COMP 1
VFB 2
ISENSE 3
RT/CT 4
8 REF
7 V_CC
6 OUTPUT
5 GND
The TL284x and TL384x series of control
integrated circuits provide the features that are
necessary to implement off-line or dc-to-dc fixed-frequency current-mode control schemes, with a minimum
number of external components. Some of the internally implemented circuits are an undervoltage lockout
(UVLO), featuring a start-up current of less than 1 mA, and a precision reference trimmed for accuracy at the
error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation
(PWM) comparator (that also provides current-limit control), and a totem-pole output stage designed to source
or sink high-peak current. The output stage, suitable for driving N-channel MOSFETs, is low when it is in the
off state.
Major differences between members of these series are the UVLO thresholds and maximum duty-cycle ranges.
Typical UVLO thresholds of 16 V (on) and 10 V (off) on the TLx842 and TLx844 devices make them ideally suited
to off-line applications. The corresponding typical thresholds for the TLx843 and TLx845 devices are 8.4 V (on)
and 7.6 V (off). The TLx842 and TLx843 devices can operate to duty cycles approaching 100%. A duty-cycle
range of 0 to 50% is obtained by the TLx844 and TLx845 by the addition of an internal toggle flip-flop, which
blanks the output off every other clock cycle.
The TL284x-series devices are characterized for operation from –40°C to 85°C. The TL384x-series devices are
characterized for operation from 0°C to 70°C.
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.
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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