ZHCSO65B January 2023 – January 2024 LMR38020-Q1
PRODUCTION DATA
- 1
- 1 特性
- 2 应用
- 3 说明
- 4 Device Comparison Table
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 Fixed Frequency Peak Current Mode Control
- 7.3.2 Adjustable Output Voltage
- 7.3.3 Enable
- 7.3.4 Switching Frequency and Synchronization (RT/SYNC)
- 7.3.5 Power-Good Flag Output
- 7.3.6 Minimum On Time, Minimum Off Time, and Frequency Foldback
- 7.3.7 Bootstrap Voltage
- 7.3.8 Overcurrent and Short Circuit Protection
- 7.3.9 Soft Start
- 7.3.10 Thermal Shutdown
- 7.4 Device Functional Modes
- 8 Application and Implementation
- 9 Device and Documentation Support
- 10Revision History
- 11Mechanical, Packaging, and Orderable Information
7.3.3 Enable
The voltage on the EN pin controls the ON or OFF operation of the LMR38020-Q1. A voltage below 0.95 V shuts the device down, while a voltage above 1.4 V is required to start the converter. The EN pin is an input and cannot be left open or floating. The simplest way to enable the operation of the LMR38020-Q1 is to connect the EN to VIN. This allows self-start-up of the LMR38020-Q1 when VIN is within the operating range.
Many applications benefit from the employment of an enable divider RENT and RENB (Figure 7-3) to establish a precision system UVLO level for the converter. System UVLO can be used for supplies operating from utility power as well as battery power. System UVLO can be used for sequencing, making sure the user has reliable operation or supply protection, such as a battery discharge level. An external logic signal can also be used to drive EN input for system sequencing and protection. Note that the EN pin voltage must never be higher than VIN + 0.3 V.
Figure 7-3 System UVLO by Enable Divider