ZHCS547K January 2010 – February 2018 LM27402
PRODUCTION DATA.
- 1 特性
- 2 应用
- 3 说明
- 4 修订历史记录
- 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 Wide Input Voltage Range
- 7.3.2 UVLO
- 7.3.3 Precision Enable
- 7.3.4 Soft-Start and Voltage Tracking
- 7.3.5 Output Voltage Setpoint and Accuracy
- 7.3.6 Voltage-Mode Control
- 7.3.7 Power Good
- 7.3.8 Inductor-DCR-Based Overcurrent Protection
- 7.3.9 Current Sensing
- 7.3.10 Power MOSFET Gate Drivers
- 7.3.11 Pre-Bias Start-up
- 7.4 Device Functional Modes
-
8 Application and Implementation
- 8.1
Application Information
- 8.1.1 Converter Design
- 8.1.2 Inductor Selection (L)
- 8.1.3 Output Capacitor Selection (COUT)
- 8.1.4 Input Capacitor Selection (CIN)
- 8.1.5 Using Precision Enable
- 8.1.6 Setting the Soft-Start Time
- 8.1.7 Tracking
- 8.1.8 Setting the Switching Frequency
- 8.1.9 Setting the Current Limit Threshold
- 8.1.10 Control Loop Compensation
- 8.1.11 MOSFET Gate Drivers
- 8.1.12 Power Loss and Efficiency Calculations
- 8.2 Typical Applications
- 8.1
Application Information
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文档支持
- 12机械、封装和可订购信息
封装选项
机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息
7.3.11 Pre-Bias Start-up
In certain applications, the output may acquire a pre-bias voltage before the LM27402 is powered on or enabled. Pre-biased conditions are managed by preventing switching until the soft-start (SS/TRACK) voltage exceeds the feedback (FB) voltage. When VSS/TRACK exceeds VFB, the LM27402 begins to switch synchronously and regulate the output voltage.
Figure 24. Pre-Bias Start-up
Prohibiting switching during a pre-biased start-up condition prevents the output from forcing parasitic paths in the system application to conduct excessive current. The LM27402 does not switch if the output is pre-biased to a voltage higher than the nominally-set output voltage.