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Texas Instruments
Texas Instruments

TL3844D Datasheet

CURRENT-MODE PWM CONTROLLERS


TL3844D Datasheet Preview


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
SLVS038E – JANUARY 1989 – REVISED DECEMBER 1999
D PACKAGE
(TOP VIEW)
COMP
NC
VFB
NC
ISENSE
NC
RT/CT
1
2
3
4
5
6
7
14 REF
13 NC
12 VCC
11 VC
10 OUTPUT
9 GND
8 POWER GROUND
NC – No internal connection
D-8 OR P PACKAGE
(TOP VIEW)
COMP
VFB
ISENSE
RT/CT
1
2
3
4
8 REF
7 VCC
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 (which 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.
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
Copyright © 1999, Texas Instruments Incorporated
1
Page 1

TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
SLVS038E – JANUARY 1989 – REVISED DECEMBER 1999
AVAILABLE OPTIONS
PACKAGED DEVICES
CHIP FORM
TA
SMALL OUTLINE SMALL OUTLINE PLASTIC DIP
(Y)
(D)
(D-8)
(P)
0°C to 70°C
TL3842D
TL3843D
TL3844D
TL3845D
TL3842D-8
TL3843D-8
TL3844D-8
TL3845D-8
TL3842P
TL3843P
TL3844P
TL3845P
TL3842Y
TL3843Y
TL3844Y
TL3845Y
–40°C to 85°C
TL2842D
TL2843D
TL2844D
TL2845D
TL2842D-8
TL2843D-8
TL2844D-8
TL2845D-8
TL2842P
TL2843P
TL2844P
TL2845P
The D and D-8 packages are available taped and reeled. Add the suffix R to the device type (i.e.,
TL3842DR or TL3842DR-8). Chip forms are tested at 25°C.
functional block diagram
VCC 12
34 V NOM
GND 9
–+
UVLO
5-V REF
EN
7
RT/CT
OSC
Vref
Good
Logic
T
3
VFB
COMP 1
ISENSE 5
Error
Amplifier
+
2R
R
S
R
1V
Current-
Sense
Comparator
The toggle flip-flop is present only in TL2844, TL2845, TL3844, and TL3845.
Pin numbers shown are for the D Package.
Internal
Bias
PWM
Latch
14 REF
11
VC
10 OUTPUT
8 POWER
GROUND
2 POST OFFICE BOX 655303 DALLAS, TEXAS 75265
Page 2

TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
SLVS038E – JANUARY 1989 – REVISED DECEMBER 1999
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage (see Note 1) (ICC < 30 mA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Self limiting
Analog input voltage range, VI (VFB and ISENSE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6.3 V
Output voltage, VO (OUTPUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 V
Input voltage, VI, (VC, D package only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 V
Supply current, ICC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 mA
Output current, IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1 A
Error amplifier output sink current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mA
Package thermal impedance, θJA (see Notes 2 and 3): D package . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86°C/W
D-8 package . . . . . . . . . . . . . . . . . . . . . . . . . . 97°C/W
P package . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85°C/W
Virtual junction temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 150°C
Output energy (capacitive load) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 µJ
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 affect device reliability.
NOTES:
1. All voltages are with respect to the device GND 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.
recommended operating conditions
Supply voltage, VCC and VC‡
Input voltage, VI, RT/CT
Input voltage, VI, VFB and ISENSE
Output voltage, VO, OUTPUT
Output voltage, VO, POWER GROUND‡
Supply current, externally limited, ICC
Average output current, IO
Reference output current, IO(ref)
Oscillator frequency, fosc
Operating virtual junction temperature, TJ
Operating free-air temperature, TA
‡ These recommended voltages for VC and POWER GROUND apply only to the D package.
TL284x
TL384x
MIN NOM MAX UNIT
30 V
0 5.5 V
0 5.5 V
0 30 V
–0.1 1 V
25 mA
200 mA
–20 mA
100 500 kHz
0 125 °C
–40 85
°C
0 70
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
3
Page 3
Part Number TL3844D
Manufactur Texas Instruments
Description CURRENT-MODE PWM CONTROLLERS
Total Page 12 Pages
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