AS384X Datasheet, PDF(1/20 Page) List of Unclassifed Manufacturers

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AS384X Datasheet, PDF (1/20 Pages) List of Unclassifed Manufacturers – Current Mode Controller

SEMICONDUCTOR

AS384x

Current Mode Controller

Features

Â¥ 2.5 V bandgap reference trimmed to

1.0% and temperature-compensated

Â¥ Standard temperature range extended

to 105Â¡C

Â¥ AS3842/3 oscillations trimmed for

precision duty cycle clamp

Â¥ AS3844/5 have exact 50% max duty

cycle clamp

Â¥ Advanced oscillator design simplifies

synchronization

Â¥ Improved specs on UVLO and

hysteresis provide more predictable

start-up and shutdown

Â¥ Improved 5 V regulator provides better

AC noise immunity

Â¥ Guaranteed performance with current

sense pulled below ground

Description

The AS3842 family of control ICs provide pin-for-pin replacement of the

industry standard UC3842 series of devices. The devices are

redesigned to provide significantly improved tolerances in power sup-

ply manufacturing. The 2.5 V reference has been trimmed to 1.0%

tolerance. The oscillator discharge current is trimmed to provide guar-

anteed duty cycle clamping rather than specified discharge current.

The circuit is more completely specified to guarantee all parameters

impacting power supply manufacturing tolerances.

In addition, the oscillator and flip-flop sections have been enhanced to

provide additional performance. The RT/CT pin now doubles as a syn-

chronization input that can be easily driven from open collector/open

drain logic outputs. This sync input is a high impedance input and can

easily be used for externally clocked systems. The new flip-flop topol-

ogy allows the duty cycle on the AS3844/5 to be guaranteed between

49 and 50%. The AS3843/5 requires less than 0.5 mA of start-up cur-

rent over the full temperature range.

Pin Configuration Ã Top view

PDIP (N)

8L SOIC (D8)

14L SOIC (D14)

COMP 1

VFB 2

ISENSE 3

RT/CT 4

8 VREG

7 VCC

6 OUT

5 GND

COMP 1

VFB 2

ISENSE 3

RT/CT 4

Ordering Information

Circuit Type:

Current Mode Controller (See Table A)

Package Style

D8 = 8 Pin Plastic SOIC

D14 = 14 Pin Plastic SOIC

N = 8 Pin Plastic DIP

AS384X D8 13

8 VREG

7 VCC

6 OUT

5 GND

COMP 1

NC 2

VFB 3

NC 4

ISENSE 5

NC 6

RT/CT 7

14 VREG

13 NC

12 VCC

11 VC

10 OUT

9 PWR G

8 GND

Packaging Option:

T = Tube

13 = Tape and Reel (13" Reel Dia)

Table A

Model

AS3842

AS3843

AS3844

AS3845

VCC(min)

7.6

VCC(on)

8.4

Duty Cycle

Typ.

97%

49.5%

ICC

0.5 mA

0.3 mA

0.5 mA

0.3 mA

ASTEC Semiconductor

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