Datasheet UC1846, UC1847, UC2846 UC2847, UC3846, UC3847 (Texas Instruments) - 10
| 制造商 | Texas Instruments |
| 描述 | UCx846/7 Current Mode PWM Controller |
| 页数 / 页 | 24 / 10 — UC1846,. UC1847. , UC2846. UC2847,. UC3846. , UC3847. www.ti.com. 7.4 … |
| 文件格式/大小 | PDF / 1.3 Mb |
| 文件语言 | 英语 |
UC1846,. UC1847. , UC2846. UC2847,. UC3846. , UC3847. www.ti.com. 7.4 Device Functional Modes. 7.4.1 Current Limit. 7.4.2 Shutdown
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UC1846, UC1847 , UC2846 UC2847, UC3846 , UC3847
SLUS352C – JANUARY 1997 – REVISED DECEMBER 2015
www.ti.com 7.4 Device Functional Modes 7.4.1 Current Limit
One of the most attractive features of a current-mode converter is the ability to limit peak-switch currents on a pulse-by-pulse basis by simply limiting the error voltage to a maximum value.
7.4.2 Shutdown
The shutdown circuit was designed to provide a fast acting general purpose shutdown port for use in implementing both protection circuitry and remote shutdown functions. The circuit may be divided into an input section consisting of a comparator with a 350-mV temperature compensated offset, and an output section consisting of a three transistor latch. Shutdown is accomplished by applying a signal greater than 350 mV to pin 16, causing the output latch to fire, and setting the PWM latch to provide an immediate signal to the outputs. 10 Submit Documentation Feedback Copyright © 1997–2015, Texas Instruments Incorporated Product Folder Links: UC1846 UC1847 UC2846 UC2847 UC3846 UC3847 Document Outline 1 Features 2 Applications 3 Description Table of Contents 4 Revision History 5 Pin Configuration and Functions 6 Specifications 6.1 Absolute Maximum Ratings 6.2 ESD Ratings 6.3 Recommended Operating Conditions 6.4 Thermal Information 6.5 Electrical Characteristics 6.6 Typical Characteristics 7 Detailed Description 7.1 Overview 7.2 Functional Block Diagram 7.3 Feature Description 7.3.1 Current Sense Amplifier 7.3.2 Oscillator 7.4 Device Functional Modes 7.4.1 Current Limit 7.4.2 Shutdown 8 Application and Implementation 8.1 Application Information 8.2 Typical Application 8.2.1 Design Requirements 8.2.2 Detailed Design Procedure 8.2.2.1 Design Switching Frequency 8.2.2.2 Error Amplifier Output Configuration 8.2.2.3 Parallel Operation Configuration 8.2.2.4 Design Pulse by Pulse Current Limit Threshold 8.2.2.5 Soft-Start and Shutdown, Restart Function Design 8.2.3 Application Curves 9 Power Supply Recommendations 10 Layout 10.1 Layout Guidelines 10.2 Layout Example 11 Device and Documentation Support 11.1 Related Links 11.2 Community Resources 11.3 Trademarks 11.4 Electrostatic Discharge Caution 11.5 Glossary 12 Mechanical, Packaging, and Orderable Information
SLUS352C – JANUARY 1997 – REVISED DECEMBER 2015
www.ti.com 7.4 Device Functional Modes 7.4.1 Current Limit
One of the most attractive features of a current-mode converter is the ability to limit peak-switch currents on a pulse-by-pulse basis by simply limiting the error voltage to a maximum value.
7.4.2 Shutdown
The shutdown circuit was designed to provide a fast acting general purpose shutdown port for use in implementing both protection circuitry and remote shutdown functions. The circuit may be divided into an input section consisting of a comparator with a 350-mV temperature compensated offset, and an output section consisting of a three transistor latch. Shutdown is accomplished by applying a signal greater than 350 mV to pin 16, causing the output latch to fire, and setting the PWM latch to provide an immediate signal to the outputs. 10 Submit Documentation Feedback Copyright © 1997–2015, Texas Instruments Incorporated Product Folder Links: UC1846 UC1847 UC2846 UC2847 UC3846 UC3847 Document Outline 1 Features 2 Applications 3 Description Table of Contents 4 Revision History 5 Pin Configuration and Functions 6 Specifications 6.1 Absolute Maximum Ratings 6.2 ESD Ratings 6.3 Recommended Operating Conditions 6.4 Thermal Information 6.5 Electrical Characteristics 6.6 Typical Characteristics 7 Detailed Description 7.1 Overview 7.2 Functional Block Diagram 7.3 Feature Description 7.3.1 Current Sense Amplifier 7.3.2 Oscillator 7.4 Device Functional Modes 7.4.1 Current Limit 7.4.2 Shutdown 8 Application and Implementation 8.1 Application Information 8.2 Typical Application 8.2.1 Design Requirements 8.2.2 Detailed Design Procedure 8.2.2.1 Design Switching Frequency 8.2.2.2 Error Amplifier Output Configuration 8.2.2.3 Parallel Operation Configuration 8.2.2.4 Design Pulse by Pulse Current Limit Threshold 8.2.2.5 Soft-Start and Shutdown, Restart Function Design 8.2.3 Application Curves 9 Power Supply Recommendations 10 Layout 10.1 Layout Guidelines 10.2 Layout Example 11 Device and Documentation Support 11.1 Related Links 11.2 Community Resources 11.3 Trademarks 11.4 Electrostatic Discharge Caution 11.5 Glossary 12 Mechanical, Packaging, and Orderable Information