ZHCSLW5A October 2019 – November 2020 LMR50410-Q1
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Device Comparison Table
- 6 Pin Configuration and Functions
- 7 Specifications
- 8 Detailed Description
-
9 Application and Implementation
- 9.1 Application Information
- 9.2
Typical Application
- 9.2.1 Design Requirements
- 9.2.2
Detailed Design Procedure
- 9.2.2.1 Custom Design With WEBENCH® Tools
- 9.2.2.2 Output Voltage Set-Point
- 9.2.2.3 Switching Frequency
- 9.2.2.4 Inductor Selection
- 9.2.2.5 Output Capacitor Selection
- 9.2.2.6 Input Capacitor Selection
- 9.2.2.7 Bootstrap Capacitor
- 9.2.2.8 Undervoltage Lockout Set-Point
- 9.2.2.9 Maximum Ambient Temperature
- 9.2.3 Application Curves
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
9.2.2.8 Undervoltage Lockout Set-Point
The system undervoltage lockout (UVLO) is adjusted using the external voltage divider network of RENT and RENB. The UVLO has two thresholds, one for power up when the input voltage is rising and one for power down or brown outs when the input voltage is falling. Equation 13 can be used to determine the VIN UVLO level.
The EN rising threshold (VENH) for LMR50410-Q1 is set to be 1.23 V (typical). Choose a value of 200 kΩ for RENB to minimize input current from the supply. If the desired VIN UVLO level is at 6.0 V, then the value of RENT can be calculated using Equation 14:
The above equation yields a value of 775.6 kΩ, a standard value of 768 kΩ is selected. The resulting falling UVLO threshold, equals 5.3 V, can be calculated by Equation 15 where EN hysteresis voltage, VEN_HYS, is 0.13 V (typical).
