UC2844AD1 STMicroelectronics, UC2844AD1 Datasheet

Switching Converters, Regulators & Controllers RO 511-UC2844BD 9/04

UC2844AD1

Manufacturer Part Number

UC2844AD1

Description

Switching Converters, Regulators & Controllers RO 511-UC2844BD 9/04

Manufacturer

STMicroelectronics

Datasheets

1.UC2844AD1.pdf (16 pages)

2.UC2844AD1.pdf (15 pages)

Specifications of UC2844AD1

Mounting Style

SMD/SMT

Package / Case

SO-8

Lead Free Status / Rohs Status

Lead free / RoHS Compliant

Available stocks

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Bonase Electronics (HK) Co., Limited

Part Number:

UC2844AD1

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UC2844AD1

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UC2844AD1013TR

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UC2844AD13TR-2

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Download datasheet (172Kb)

The UC384xA family of control ICs provides the

necessary features to implement off-line or DC to

DC fixed frequency current mode control schemes

with a minimal external parts count. Internally im-

plemented circuits include a trimmed oscillator for

precise DUTY CYCLE CONTROL under voltage

lockout featuring start-up current less than 0.5mA,

a precision reference trimmed for accuracy at the

error amp input, logic to insure latched operation,

a PWM comparator which also provides current

limit control, and a totem pole output stage de-

signed to source or sink high peak current. The

output stage, suitable for driving N-Channel MOS-

FETs, is low in the off-state.

Figure 2. Block Diagram (toggle flip flop used only in UC3844A and UC3845A)

May 2004

HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER

TRIMMED OSCILLATOR DISCHARGE

CURRENT

CURRENT MODE OPERATION TO 500kHz

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

LOW START-UP CURRENT (< 0.5mA)

DOUBLE PULSE SUPPRESSION

FEATURES

DESCRIPTION

CURRENT

GROUND

SENSE

COMP

RT/CT

VFB

34V

ERROR AMP.

OSC

2.50V

UVLO

S/R

REF

VREF GOOD

LOGIC

Differences between members of this family are

the under-voltage lockout thresholds and maxi-

mum duty cycle ranges. The UC3842A and

UC3844A have UVLO thresholds of 16V (on) and

10V (off), ideally suited off-line applications The

corresponding thresholds for the UC3843A and

UC3845A are 8.5 V and 7.9V. The UC3842A and

UC3843A can operate to duty cycles approaching

100%. A range of the zero to < 50 % is obtained by

the UC3844A and UC3845A by the addition of an

internal toggle flip flop which blanks the output off

every other clock cycle.

Figure 1. Package

Table 1. Order Codes

COMPARATOR

UC2842AD1; UC3842AD1;

UC2843AD1; UC3843AD1;

UC2844AD1; UC3844AD1;

UC2845AD1; UC3845AD1

UC2842AN; UC3842AN;

UC2843AN; UC3843AN;

UC2844AN; UC3844AN;

UC2845AN; UC3845AN

CURRENT

SENSE

INTERNAL

BIAS

Part Number

LATCH

PWM

DIP-8

D95IN331

5V 50mA

OUTPUT

VREF

NOT FOR NEW DESIGN

UC284XA

UC384XA

SO-8

Package

DIP-8

SO-8

REV. 5

1/16

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