ZHCSL10C March 2020 – June 2021 LM61440-Q1
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 说明（续）
- 6 Device Comparison Table
- 7 Pin Configuration and Functions
- 8 Specifications
-
9 Detailed Description
- 9.1 Overview
- 9.2 Functional Block Diagram
- 9.3
Feature Description
- 9.3.1 EN/SYNC Uses for Enable and VIN UVLO
- 9.3.2 EN/SYNC Pin Uses for Synchronization
- 9.3.3 Clock Locking
- 9.3.4 Adjustable Switching Frequency
- 9.3.5 PGOOD Output Operation
- 9.3.6 Internal LDO, VCC UVLO, and BIAS Input
- 9.3.7 Bootstrap Voltage and VCBOOT-UVLO (CBOOT Pin)
- 9.3.8 Adjustable SW Node Slew Rate
- 9.3.9 Spread Spectrum
- 9.3.10 Soft Start and Recovery From Dropout
- 9.3.11 Output Voltage Setting
- 9.3.12 Overcurrent and Short Circuit Protection
- 9.3.13 Thermal Shutdown
- 9.3.14 Input Supply Current
- 9.4 Device Functional Modes
-
10Application and Implementation
- 10.1 Application Information
- 10.2
Typical Application
- 10.2.1 Design Requirements
- 10.2.2
Detailed Design Procedure
- 10.2.2.1 Choosing the Switching Frequency
- 10.2.2.2 Setting the Output Voltage
- 10.2.2.3 Inductor Selection
- 10.2.2.4 Output Capacitor Selection
- 10.2.2.5 Input Capacitor Selection
- 10.2.2.6 BOOT Capacitor
- 10.2.2.7 BOOT Resistor
- 10.2.2.8 VCC
- 10.2.2.9 BIAS
- 10.2.2.10 CFF and RFF Selection
- 10.2.2.11 External UVLO
- 10.2.3 Application Curves
- 11Power Supply Recommendations
- 12Layout
- 13Device and Documentation Support
- 14Mechanical, Packaging, and Orderable Information
9.3.4 Adjustable Switching Frequency
A resistor tied from the device RT pin to AGND is used to set operating frequency. Use Equation 2 or refer to Figure 9-5 for resistor values. Note that a resistor value outside of the recommended range can cause the device to shut down. This prevents unintended operation if RT pin is shorted to ground or left open. Do not apply a pulsed signal to this pin to force synchronization. If synchronization is needed, refer to Section 9.3.2.
Figure 9-5 Setting Clock Frequency