Texas Instruments TL3845DR-8, TL3845D-8, TL3845DR, TL3845D, TL3844Y Datasheet

TL284x, TL384x

CURRENT-MODE PWM CONTROLLERS

SLVS038E – JANUARY 1989 – REVISED DECEMBER 1999

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

COMP

ISENSE

NC – No internal connection

D PACKAGE

(TOP VIEW)

1
2

NC

3

VFB

4

NC

5
6

NC

RT/CT

7

D-8 OR P PACKAGE

(TOP VIEW)

REF

14
13

NC

12

V

CC

11

VC

10

OUTPUT

9

GND

8

POWER GROUND

Resistance

D

Designed to Be Interchangeable With
UC2842 and UC3842 Series

description

COMP

VFB

ISENSE

RT/CT

1
2
3
4

8
7
6
5

REF
V

CC

OUTPUT
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 (of f) 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.

Copyright  1999, Texas Instruments Incorporated

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

1

TL284x, TL384x

CHIP FORM

CURRENT-MODE PWM CONTROLLERS

SLVS038E – JANUARY 1989 – REVISED DECEMBER 1999

T

A

0°C to 70°C

–40°C to 85°C

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).

functional block diagram

12

V

CC

SMALL OUTLINE

(D)

TL3842D
TL3843D
TL3844D
TL3845D

TL2842D
TL2843D
TL2844D
TL2845D

Chip forms are tested at 25°C.

AVAILABLE OPTIONS

PACKAGED DEVICES

SMALL OUTLINE

(D-8)

TL3842D-8
TL3843D-8
TL3844D-8
TL3845D-8

TL2842D-8
TL2843D-8
TL2844D-8
TL2845D-8

PLASTIC DIP

(P)

TL3842P
TL3843P
TL3844P
TL3845P

TL2842P
TL2843P
TL2844P
TL2845P

(Y)

TL3842Y
TL3843Y
TL3844Y
TL3845Y

–
–
–
–

34 V NOM

9

GND

VFB

7

3

1

5

RT/CT

COMP

ISENSE

†

The toggle flip-flop is present only in TL2844, TL2845, TL3844, and TL3845.

Pin numbers shown are for the D Package.

–

OSC

Error

Amplifier

+
–

UVLO

+

2R

5-V REF

EN

R1 V

Current-

Comparator

V

ref

Good
Logic

Sense

14

REF

Internal

Bias

11

VC

10

OUTPUT

†

T

S

R

PWM
Latch

8

POWER
GROUND

2

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

O

T

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, V

(OUTPUT) 35 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

O

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, θ

(see Notes 2 and 3): D package 86°C/W. . . . . . . . . . . . . . . . . . . . . . . . . . . .

JA

D-8 package 97°C/W. . . . . . . . . . . . . . . . . . . . . . . . . .

P package 85°C/W. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Virtual junction temperature range, T

0°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

J

Output energy (capacitive load) 5 µJ. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Lead temperature, 1,6 mm (1/16 inch) from case for 10 seconds 260°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Storage temperature range, T

†

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),
ambient temperature is PD = (TJ(max) – TA)/

3. The package thermal impedance is calculated in accordance with JESD 51.

–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

stg

θ

, and TA. The maximum allowable power dissipation at any allowable

θ

JA

JA

. Operating at the absolute maximum TJ of 150°C can impact reliability.

recommended operating conditions

MIN NOM MAX UNIT

osc

O

O(ref)

‡

‡

CC

J

A

TL284x –40 85
TL384x

–0.1 1 V

100 500 kHz

0 125

0 70

Supply voltage, VCC and VC
Input voltage, VI, RT/CT 0 5.5 V
Input voltage, VI, VFB and ISENSE 0 5.5 V
Output voltage, VO, OUTPUT 0 30 V
Output voltage, VO, POWER GROUND
Supply current, externally limited, I
Average output current, I
Reference output current, I
Oscillator frequency, f
Operating virtual junction temperature, T

perating free-air temperature,

‡

These recommended voltages for VC and POWER GROUND apply only to the D package.

30 V

25 mA
200 mA
–20 mA

°C

°C

†

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

3

TL284x, TL384x

PARAMETER

TEST CONDITIONS

UNIT

PARAMETER

TEST CONDITIONS

UNIT

PARAMETER

TEST CONDITIONS

UNIT

CURRENT-MODE PWM CONTROLLERS

SLVS038E – JANUARY 1989 – REVISED DECEMBER 1999

electrical characteristics over recommended operating free-air temperature range, V
Note 4), R

= 10 kΩ, C

T

= 3.3 nF (unless otherwise specified)

T

= 15 V (see

CC

reference section

TL284x TL384x

MIN TYP†MAX MIN TYP†MAX

Output voltage IO = 1 mA, TA = 25°C 4.95 5 5.05 4.9 5 5.1 V
Line regulation VCC = 12 V to 25 V 6 20 6 20 mV
Load regulation IO = 1 mA to 20 mA 6 25 6 25 mV
Temperature coefficient

of output voltage
Output voltage

with worst-case variation
Output noise voltage f = 10 Hz to 10 kHz, TA = 25°C 50 50 µV
Output-voltage long-term drift After 1000 h at TA = 25°C 5 25 5 25 mV
Short-circuit output current –30 –100 –180 –30 –100 –180 mA

†

All typical values are at TA = 25°C.

NOTE 4: Adjust VCC above the start threshold before setting it to 15 V .

VCC = 12 V to 25 V, IO = 1 mA to 20 mA 4.9 5.1 4.82 5.18 V

0.2 0.4 0.2 0.4 mV/°C

oscillator section

TL284x TL384x

MIN TYP†MAX MIN TYP†MAX

Oscillator frequency (see Note 5) TA = 25°C 47 52 57 47 52 57 kHz
Frequency change with supply voltage VCC = 12 V to 25 V 2 10 2 10 Hz/kHz
Frequency change with temperature 50 50 Hz/kHz
Peak-to-peak amplitude at RT/CT 1.7 1.7 V

†

All typical values are at TA = 25°C.

NOTES: 4. Adjust VCC above the start threshold before setting it to 15 V .

5. Output frequency equals oscillator frequency for the TLx842 and TLx843. Output frequency is one-half oscillator frequency for the
TLx844 and TLx845.

error-amplifier section

TL284x TL384x

MIN TYP†MAX MIN TYP†MAX

Feedback input voltage COMP at 2.5 V 2.45 2.50 2.55 2.42 2.50 2.58 V
Input bias current –0.3 –1 –0.3 –2 µA
Open-loop voltage amplification VO = 2 V to 4 V 65 90 65 90 dB
Gain-bandwidth product 0.7 1 0.7 1 MHz
Supply-voltage rejection ratio VCC = 12 V to 25 V 60 70 60 70 dB
Output sink current VFB at 2.7 V, COMP at 1.1 V 2 6 2 6 mA
Output source current VFB at 2.3 V, COMP at 5 V –0.5 –0.8 –0.5 –0.8 mA
High-level output voltage VFB at 2.3 V, RL = 15 kΩ to GND 5 6 5 6 V
Low-level output voltage VFB at 2.7 V, RL = 15 kΩ to GND 0.7 1.1 0.7 1.1 V

†

All typical values are at TA = 25°C.

NOTE 4: Adjust VCC above the start threshold before setting it to 15 V .

4

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265