HIGH-PERFORMANCE CURRENT-MODE PWM CONTROLLERS
www.ti.com
SLVS610A – AUGUST 2006 – REVISED SEPTEMBER 2006
FEATURES
•
•
•
•
•
•
•
•
Low Start-Up Current (<0.5 mA)
Trimmed Oscillator Discharge Current
Current Mode Operation to 500 kHz
Automatic Feed-Forward Compensation
Latching PWM for Cycle-by-Cycle Current
Limiting
Internally Trimmed Reference With
Undervoltage Lockout
High-Current Totem-Pole Output
Undervoltage Lockout With Hysteresis
Double-Pulse Suppression
D (SOIC) OR P (PDIP) PACKAGE
(TOP VIEW)
COMP
VFB
I
SENSE
R
T
/C
T
1
2
3
4
8
7
6
5
V
REF
V
CC
OUTPUT
GND
D (SOIC) PACKAGE
(TOP VIEW)
COMP
NC
VFB
NC
I
SENSE
NC
R
T
/C
T
1
2
3
4
5
6
7
14
13
12
11
10
9
8
V
REF
NC
V
CC
VC
OUTPUT
GND
POWER GROUND
NC − No internal connection
DESCRIPTION/ORDERING INFORMATION
The TL284xB and TL384xB 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. Internally implemented circuits include an undervoltage lockout (UVLO) and a precision
reference that is 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.
The TL284xB and TL384xB series are pin compatible with the standard TL284x and TL384x with the following
improvements. The start-up current is specified to be 0.5 mA (max), while the oscillator discharge current is
trimmed to 8.3 mA (typ). In addition, during undervoltage lockout conditions, the output has a maximum
saturation voltage of 1.2 V while sinking 10 mA (V
CC
= 5 V).
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 TLx842B and TLx844B devices make them ideally
suited to off-line applications. The corresponding typical thresholds for the TLx843B and TLx845B devices are
8.4 V (on) and 7.6 V (off). The TLx842B and TLx843B devices can operate to duty cycles approaching 100%. A
duty-cycle range of 0% to 50% is obtained by the TLx844B and TLx845B by the addition of an internal toggle
flip-flop, which blanks the output off every other clock cycle.The TL284xB-series devices are characterized for
operation from –40°C to 85°C. The TL384xB-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 the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2006, Texas Instruments Incorporated
TI [ TEXAS INSTRUMENTS ]
