UC28023

UC28025

SLUS557B − MARCH 2003 − REVISED APRIL 2004

ECONOMY HIGHSPEED PWM CONTROLLER

1

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FEATURES

or Voltage Mode (with Feed-Forward) Control

Methods

Range

Suppression

APPLICATIONS

Current Mode, or Average Current Mode

Control Methods

Designs

DESCRIPTION

The UC28023 and UC28025 are fixed-frequency

PWM controllers optimized for high-frequency

switched-mode power supply applications. The

UC28023 is a single output PWM for single-ended

topologies

while

the

UC28025

offers

dual

alternating outputs for double-ended and full

bridge topologies.

Targeted for cost effective solutions with minimal

external

components,

UC2802x

include

an

oscillator, a temperature compensated reference,

a wide band width error amplifier, a high-speed

current-sense

comparator

and

high-current

active-high totem-pole outputs to directly drive

external MOSFETs.

Protection circuitry includes a current limit

comparator

with

a

1-V

threshold,

a

TTL

compatible shutdown port, and a soft-start pin

which will double as a maximum duty cycle clamp.

The logic is fully latched to provide jitter free

operation and prohibit multiple pulses at an

output. An undervoltage lockout section with

800 mV of hysteresis assures low start-up

current. During undervoltage lockout, the outputs

are high impedance. Particular care was given to

minimizing

propagation

delays

through

the

comparators and logic circuitry while maximizing

bandwidth and slew rate of the error amplifier.

Devices are available in the industrial temperature

range of −40

°C to 105°C. Package offerings are

16-pin SOICW (DW), or 16-pin PDIP (N)

packages.

ORDERING INFORMATION

TA = TJ

OUTPUT

EXTERNAL CURRENT

PACKAGED DEVICES

TA = TJ

OUTPUT

CONFIGURATION

EXTERNAL CURRENT

LIMIT REFERENCE

PDIP-16 (N)

SOICW−16 (DW)

−40

°C to 105°C

Single

Yes

UC28023N

UC28023DW

−40

°C to 105°C

Dual Alternating

No

UC28025N

UC28025DW

(1) The DW package are also available taped and reeled. Add an R suffix to the device type (i.e., UC28023DWR (2,000 devices per reel).

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

 2004, Texas Instruments Incorporated