7

5

4

2

1

3

8

7

6

5

V

CC

Gnd

R

V

FB

Comp

C/S

V

REF

5.0 V

50 mA

V

C

Output

Pwr

Ground

PWM

Latch

5-V

REF

S/R

UVLO

34 V

2.5 V

Osc

Error

Amplifier

2R

R

1 V

Current

Sense

Comparator

Internal

Bias

V

Good

Logic

REF

S

R

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UC1842A-SP, UC1843A-SP, UC1844A-SP

SLUS872D – JANUARY 2009 – REVISED MAY 2015

UC184xA-SP QML Class V, Current-Mode PWM Controller

1 Features

2 Applications

1

•

QML Class V (QMLV) Qualified, SMD 5962-86704

•

DC-DC Converters

•

•

Supports Various Topologies:

•

Optimized for Offline and DC-to-DC Converters

–

Flyback, Forward, Buck, Boost

•

Low Start-Up Current (<0.5 mA)

–

Push-Pull, Half-Bridge, Full Bridge With

External Interface Circuit

•

Trimmed Oscillator Discharge Current

•

Available in Military Temperature Range (–55°C to

•

Automatic Feed Forward Compensation

125°C)

•

Pulse-by-Pulse Current Limiting

•

Enhanced Load Response Characteristics

3 Description

•

Undervoltage Lockout (UVLO) With Hysteresis

The UC184xA family of control ICs is a pin-for-pin

•

Double-Pulse Suppression

compatible improved version of the UC184x family.

Providing the necessary features to control current-

•

High-Current Totem-Pole Output

mode switched-mode power supplies, this device has

•

Internally-Trimmed Bandgap Reference

the following improved features. Start up current is

•

500-kHz Operation

specified to be less than 0.5 mA. Oscillator discharge

is trimmed to 8.3 mA. During UVLO, the output stage

•

over 5 V.

The Device Comparison Table shows the difference

between members of this family. Reference the

individual product data sheets for ordering the

radiation-improved version if available.

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (NOM)

(1)

The LDR improved die is only available in the UC1843A-SP

UC1842A-SP

CDIP (8)

6.67 mm × 9.60 mm

(orderable as 5962-8670409VPA). Contact factory to request

UC1843A-SP

an LDR-improved version of the UC1842A-SP or UC1844A-

LCCC (20)

8.89 mm × 8.89 mm

UC1844A-SP

SP.

(2)

Radiation tolerance is a typical value based upon initial device

(1) For all available packages, see the orderable addendum at

qualification with dose rate = 10 mrad/s. Radiation lot

the end of the data sheet.

acceptance testing is available - contact factory for details.

4 Simplified Schematic

1

An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.