UC2846 PWM Controller Datasheet

UC2846 Datasheet, PDF, Equivalent


Part Number

UC2846

Description

Current Mode PWM Controller

Manufacture

etcTI

Total Page 23 Pages
Datasheet
Download UC2846 Datasheet


UC2846
Product
Folder
Sample &
Buy
Technical
Documents
Tools &
Software
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UC1846, UC1847, UC2846
UC2847, UC3846, UC3847
SLUS352C – JANUARY 1997 – REVISED DECEMBER 2015
UCx846/7 Current Mode PWM Controller
1 Features
1 Automatic Feedforward Compensation
• Programmable Pulse-by-Pulse Current Limiting
• Automatic Symmetry Correction in Push-Pull
Configuration
• Enhanced Load Response Characteristics
• Parallel Operation Capability for Modular Power
Systems
• Differential Current Sense Amplifier with Wide
Common Mode Range
• Double-Pulse Suppression
• 500-mA (Peak) Totem-pole Outputs
• ±1% Band Gap Reference
• Undervoltage Lockout
• Soft-Start Capability
• Shutdown Terminal
• 500-kHz Operation
2 Applications
• Telecommunication Power Converters
• Industrial Power Converters
3 Description
The UC1846/7 family of control devices provides all
of the necessary features to implement fixed-
frequency, current-mode control schemes while
maintaining a minimum external parts count. The
superior performance of this technique can be
measured in improved line regulation, enhanced load
response characteristics, and a simpler, easier-to-
design control loop. Topological advantages include
inherent pulse-by-pulse current limiting capability,
automatic symmetry correction for push-pull
converters, and the ability to parallel power modules
while maintaining equal current sharing.
Protection circuitry includes built-in undervoltage
lockout and programmable current limit, in addition to
soft-start capability. A shutdown function is also
available, which can initiate either a complete
shutdown with automatic restart or latch the supply
off.
Other features include fully-latched operation, double-
pulse suppression, deadline adjust capability, and a
±1% trimmed band gap reference.
The UC1846 features low outputs in the OFF state,
while the UCx847 features high outputs in the OFF
state.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
UC1846
LCCC (20)
CDIP (16)
8.89 mm × 8.89 mm
6.92 mm × 19.56 mm
PLCC (20)
8.96 mm × 8.96 mm
UC2846, UC3846 SOIC (16)
7.5 mm × 10.3 mm
PDIP (16)
6.35 mm × 19.3 mm
SOIC (16)
UC2847, UC3847
PDIP (16)
7.5 mm × 10.3 mm
6.35 mm × 19.3 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
VIN
100µF
Block Diagram
.1µF
.5k
.005µF
3.2k
3.2k
15
2 VREF
VIN
VC 13
9
RT
AOUT 11
8
CT
C/S+
UCX846
5
+E/A
BOUT
4
14
6
-E/A
3
C/S-
180Ÿ
2W
.05µF
68Ÿ
1k
68Ÿ 1k
.05µF
.0015
7 COMP
CS/SS 1
68k SH-DN GND
16 12
1.5k
1k
VREF
2N4150
1N4245
2N4150
1N4245
.5Q
UES1402
200µH
VO
UES1402
300µF
3.6k
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.

UC2846
UC1846, UC1847, UC2846
UC2847, UC3846, UC3847
SLUS352C – JANUARY 1997 – REVISED DECEMBER 2015
www.ti.com
Table of Contents
1 Features .................................................................. 1
2 Applications ........................................................... 1
3 Description ............................................................. 1
4 Revision History..................................................... 2
5 Pin Configuration and Functions ......................... 3
6 Specifications......................................................... 4
6.1 Absolute Maximum Ratings ...................................... 4
6.2 ESD Ratings.............................................................. 4
6.3 Recommended Operating Conditions....................... 4
6.4 Thermal Information .................................................. 4
6.5 Electrical Characteristics........................................... 5
6.6 Typical Characteristics .............................................. 7
7 Detailed Description .............................................. 8
7.1 Overview ................................................................... 8
7.2 Functional Block Diagram ......................................... 8
7.3 Feature Description................................................... 8
7.4 Device Functional Modes........................................ 10
8 Application and Implementation ........................ 11
8.1 Application Information............................................ 11
8.2 Typical Application ................................................. 11
9 Power Supply Recommendations...................... 15
10 Layout................................................................... 16
10.1 Layout Guidelines ................................................. 16
10.2 Layout Example .................................................... 16
11 Device and Documentation Support ................. 17
11.1 Related Links ........................................................ 17
11.2 Community Resources.......................................... 17
11.3 Trademarks ........................................................... 17
11.4 Electrostatic Discharge Caution ............................ 17
11.5 Glossary ................................................................ 17
12 Mechanical, Packaging, and Orderable
Information ........................................................... 17
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (July 2010) to Revision C
Page
• Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section. ................................................................................................. 1
• Removed soldering temperature ........................................................................................................................................... 4
Changes from Revision A (February 2002) to Revision B
Page
• Updated Block Diagram. ........................................................................................................................................................ 1
2 Submit Documentation Feedback
Copyright © 1997–2015, Texas Instruments Incorporated
Product Folder Links: UC1846 UC1847 UC2846 UC2847 UC3846 UC3847


Features Product Folder Sample & Buy Technical Documents Tools & Software Support & Community UC1846, UC1847, UC2846 UC284 7, UC3846, UC3847 SLUS352C – JANUARY 1997 – REVISED DECEMBER 2015 UCx846/7 Current Mode PWM Controller 1 Feature s •1 Automatic Feedforward Compensati on • Programmable Pulse-by-Pulse Curr ent Limiting • Automatic Symmetry Cor rection in Push-Pull Configuration • Enhanced Load Response Characteristics • Parallel Operation Capability for M odular Power Systems • Differential C urrent Sense Amplifier with Wide Common Mode Range • Double-Pulse Suppressio n • 500-mA (Peak) Totem-pole Outputs • ±1% Band Gap Reference • Undervo ltage Lockout • Soft-Start Capability • Shutdown Terminal • 500-kHz Oper ation 2 Applications • Telecommunicat ion Power Converters • Industrial Pow er Converters 3 Description The UC1846 /7 family of control devices provides a ll of the necessary features to impleme nt fixedfrequency, current-mode control schemes while maintaining a minimum external parts count. .
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