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UC1844A-SP Datasheet Preview

UC1844A-SP Datasheet

current-mode PWM controller

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UC1842A-SP, UC1844A-SP

SLUS872E – JANUARY 2009 – REVISED FEBRUARY 2019

UC184xA-SP QML class V, current-mode PWM controller

1 Features

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

• Rad-Tolerant: 30-krad(Si) TID (1) (2)

• Optimized for Offline and DC-to-DC Converters

• Low Start-Up Current (< 0.5 mA)

• Trimmed Oscillator Discharge Current

• Automatic Feed Forward Compensation

• Pulse-by-Pulse Current Limiting

• Enhanced Load Response Characteristics

• Undervoltage Lockout (UVLO) With Hysteresis

• Double-Pulse Suppression

• High-Current Totem-Pole Output

• Internally-Trimmed Bandgap Reference

• 500-kHz Operation

• Low RO Error Amplifier

2 Applications

• DC-DC Converters

• Supports Various Topologies:

– Flyback, Forward, Buck, Boost

– Push-Pull, Half-Bridge, Full-Bridge With

External Interface Circuit

• Available in Military Temperature Range (–55°C to

125°C)

3 Description

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

compatible improved version of the UC184x family.

Providing the necessary characteristics to control

current-mode switched-mode power supplies, this

device has improved features. Start-up current is

specified to be less than 0.5 mA and oscillator

discharge is trimmed to 8.3 mA. During UVLO, the

output stage can sink at least 10 mA at less than 1.2

V for VCC 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.

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

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

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

SP.

(2) Radiation tolerance is a typical value based upon initial device

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

acceptance testing is available - contact factory for details.

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (NOM)

UC1842A-SP

UC1844A-SP

CDIP (8)

LCCC (20)

6.67 mm × 9.60 mm

8.89 mm × 8.89 mm

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

the end of the data sheet.

Simplified Schematic

VCC 7

Gnd 5

RT/CT 4

VFB 2

Comp 1

C/S 3

34 V

UVLO

S/R

5-V

REF

2.5 V

Osc

Error

Amplifier

VREF

Good

Logic

Internal

Bias

2R S

R 1V

R PWM

Latch

Current

Sense

Comparator

8 VREF

5.0 V

50 mA

7 VC

6 Output

5 Pwr

Ground

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.

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UC1844A-SP Datasheet Preview

UC1844A-SP Datasheet

current-mode PWM controller

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UC1842A-SP, UC1844A-SP

SLUS872E – JANUARY 2009 – REVISED FEBRUARY 2019

www.ti.com

Table of Contents

1 Features .................................................................. 1

2 Applications ........................................................... 1

3 Description ............................................................. 1

4 Revision History..................................................... 2

5 Device Comparison Table..................................... 3

6 Pin Configuration and Functions ......................... 3

7 Specifications......................................................... 4

7.1 Absolute Maximum Ratings ...................................... 4

7.2 ESD Ratings.............................................................. 4

7.3 Recommended Operating Conditions....................... 4

7.4 Thermal Information .................................................. 4

7.5 Electrical Characteristics........................................... 5

7.6 Electrical Characteristics (Radiation-Improved

Devices) ..................................................................... 7

7.7 Typical Characteristics .............................................. 8

8 Detailed Description .............................................. 9

8.1 Overview ................................................................... 9

8.2 Functional Block Diagram ......................................... 9

8.3 Feature Description................................................... 9

8.4 Device Functional Modes........................................ 14

9 Application and Implementation ........................ 15

9.1 Application Information............................................ 15

9.2 Typical Application .................................................. 15

10 Power Supply Recommendations ..................... 23

11 Layout................................................................... 23

11.1 Layout Guidelines ................................................. 23

11.2 Layout Example .................................................... 24

12 Device and Documentation Support ................. 25

12.1 Related Links ........................................................ 25

12.2 Receiving Notification of Documentation Updates 25

12.3 Community Resources.......................................... 25

12.4 Trademarks ........................................................... 25

12.5 Electrostatic Discharge Caution ............................ 25

12.6 Glossary ................................................................ 25

13 Mechanical, Packaging, and Orderable

Information ........................................................... 25

4 Revision History

Changes from Revision D (May 2015) to Revision E

Page

• Removed UC1843A-SP part from this data sheet.................................................................................................................. 1

• Changed the Pin Configuration images.................................................................................................................................. 3

• Changed CT (pF) To: CT (µF) in Equation 1........................................................................................................................ 17

Changes from Revision C (March 2015) to Revision D

Page

• Updated features to remove radiation hardness assurance................................................................................................... 1

• Updated table notes for Electrical Characteristics ................................................................................................................. 5

• Updated table note in Electrical Characteristics (Radiation-Improved Devices) ................................................................... 7

• Corrected minimum discharge current in Electrical Characteristics (Radiation-Improved Devices) ..................................... 7

• Corrected input voltage unit to V and MIN and MAX values ................................................................................................. 7

• Decreased set point variation over temperature from ±10% to ±2% ................................................................................... 13

Changes from Revision B (October 2013) to Revision C

Page

• Added ESD Ratings table, Typical Characteristics, Detailed Description, Application and Implementation, Power

Supply Recommendations, Layout, and Device and Documentation Support sections ........................................................ 1

• Removed UC1845A-SP part from this data sheet.................................................................................................................. 1

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UC1844A-SP Datasheet

current-mode PWM controller

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current-mode PWM controller

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