ZHCSMU1G October 2020 – May 2024 LMR43610-Q1 , LMR43620-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 Enable, Start-Up, and Shutdown
- 7.3.2 External CLK SYNC (with MODE/SYNC)
- 7.3.3 Adjustable Switching Frequency (with RT)
- 7.3.4 Power-Good Output Operation
- 7.3.5 Internal LDO, VCC, and VOUT/FB Input
- 7.3.6 Bootstrap Voltage and VBOOT-UVLO (BOOT Terminal)
- 7.3.7 Output Voltage Selection
- 7.3.8 Spread Spectrum
- 7.3.9 Soft Start and Recovery from Dropout
- 7.3.10 Current Limit and Short Circuit
- 7.3.11 Thermal Shutdown
- 7.3.12 Input Supply Current
- 7.4 Device Functional Modes
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Application
- 8.2.1 Design Requirements
- 8.2.2 Detailed Design Procedure
- 8.2.3 Application Curves
- 8.3 Best Design Practices
- 8.4 Power Supply Recommendations
- 8.5 Layout
- 9 Device and Documentation Support
- 10Revision History
- 11Mechanical, Packaging, and Orderable Information
7.4.3.2.1 Diode Emulation
Diode emulation prevents reverse current through the inductor which requires a lower frequency needed to regulate given a fixed peak inductor current. Diode emulation also limits ripple current as frequency is reduced. With a fixed peak current, as output current is reduced to zero, frequency must be reduced to near zero to maintain regulation.
The LMR436x0-Q1 has a minimum peak inductor current setting (see IPEAKMIN in Electrical Characteristics) while in auto mode. After current is reduced to a low value with fixed input voltage, on time is constant. Regulation is then achieved by adjusting frequency. This mode of operation is called PFM mode regulation.