ZHCSLU2C December 2021 – August 2024 LM63440-Q1 , LM63460-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 Input Voltage Range (VIN1, VIN2)
- 7.3.2 Output Voltage Setpoint (FB)
- 7.3.3 Precision Enable and Input Voltage UVLO (EN/SYNC)
- 7.3.4 Frequency Synchronization (EN/SYNC)
- 7.3.5 Clock Locking
- 7.3.6 Adjustable Switching Frequency (RT)
- 7.3.7 Power-Good Monitor (PGOOD)
- 7.3.8 Bias Supply Regulator (VCC, BIAS)
- 7.3.9 Bootstrap Voltage and UVLO (CBOOT)
- 7.3.10 Spread Spectrum
- 7.3.11 Soft Start and Recovery From Dropout
- 7.3.12 Overcurrent and Short-Circuit Protection
- 7.3.13 Thermal Shutdown
- 7.3.14 Input Supply Current
- 7.4 Device Functional Modes
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Applications
- 8.2.1 Design 1 – Automotive Synchronous 6A Buck Regulator at 2.1MHz
- 8.2.2
Design 2 – Automotive Synchronous 4A Buck Regulator at 2.1MHz
- 8.2.2.1 Design Requirements
- 8.2.2.2
Detailed Design Procedure
- 8.2.2.2.1 Custom Design With WEBENCH® Tools
- 8.2.2.2.2 Setting the Output Voltage
- 8.2.2.2.3 Choosing the Switching Frequency
- 8.2.2.2.4 Inductor Selection
- 8.2.2.2.5 Output Capacitor Selection
- 8.2.2.2.6 Input Capacitor Selection
- 8.2.2.2.7 Bootstrap Capacitor
- 8.2.2.2.8 VCC Capacitor
- 8.2.2.2.9 BIAS Power Connection
- 8.2.2.2.10 Feedforward Network
- 8.2.2.2.11 Input Voltage UVLO
- 8.2.2.3 Application Curves
- 8.2.3 Design 3 – Automotive Synchronous 6A Buck Regulator at 400kHz
- 8.3 Power Supply Recommendations
- 8.4 Layout
- 9 Device and Documentation Support
- 10Revision History
- 11Mechanical, Packaging, and Orderable Information
7.3.2 Output Voltage Setpoint (FB)
While dependent on switching frequency and load current levels, the LM634x0-Q1 is generally capable of providing an output voltage in the range of 1V to a maximum of slightly less than the input voltage. Define the output voltage setpoint with feedback resistors designated as RFBT and RFBB as shown in Figure 7-1.
The LM634X0-Q1 uses a 1V reference voltage, and the internal error amplifier regulates the FB voltage to be equal to the reference voltage. Use Equation 1 to determine RFBB for a desired output voltage setpoint and a given value of RFBT.
While RFBT is generally in the range of 10kΩ to 1MΩ, use a value of 100kΩ for improved noise immunity (relative to higher resistances such as 1MΩ) and reduced current consumption (compared to lower resistance values).