ZHCSLU1B October 2022 – August 2024 LM64440-Q1 , LM64460-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)
- 7.3.4 MODE/SYNC Operation
- 7.3.5 Clock Locking
- 7.3.6 Power-Good Monitor (PGOOD)
- 7.3.7 Bias Supply Regulator (VCC, BIAS)
- 7.3.8 Bootstrap Voltage and UVLO (CBOOT)
- 7.3.9 Spread Spectrum
- 7.3.10 Soft Start and Recovery From Dropout
- 7.3.11 Overcurrent and Short-Circuit Protection
- 7.3.12 Thermal Shutdown
- 7.3.13 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
- 8.3 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 LM644x0-Q1 is generally capable of providing an output voltage in the range of 1V to a maximum of slightly less than the input voltage. If the LM64460-Q1 converter is a fixed 3.3V or 5V output option, simply connect FB to the output at the point of regulation. With an adjustable output voltage version, define the output voltage setpoint with feedback resistors designated as RFBT and RFBB as shown in Figure 7-1.
Adjustable versions of the converter use 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).