ZHCSNW4 October 2022 LM5012-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
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3
Feature Description
- 8.3.1 Control Architecture
- 8.3.2 Internal VCC Regulator and Bootstrap Capacitor
- 8.3.3 Regulation Comparator
- 8.3.4 Internal Soft Start
- 8.3.5 On-Time Generator
- 8.3.6 Current Limit
- 8.3.7 N-Channel Buck Switch and Driver
- 8.3.8 Schottky Diode Selection
- 8.3.9 Enable/Undervoltage Lockout (EN/UVLO)
- 8.3.10 Power Good (PGOOD)
- 8.3.11 Thermal Protection
- 8.4 Device Functional Modes
- 9 Application and Implementation
- 10Device and Documentation Support
- 11Mechanical, Packaging, and Orderable Information
8.3.3 Regulation Comparator
The feedback voltage at FB is compared to an internal 1.2-V reference. The LM5012-Q1 voltage regulation loop regulates the output voltage by maintaining the FB voltage equal to the internal reference voltage, VREF. A resistor divider programs the ratio from output voltage, VOUT, to FB.
For a target VOUT setpoint, use Equation 2 to calculate RFB2 based on the selected RFB1.
TI recommends selecting RFB1 in the range of 100 kΩ to 1 MΩ for most applications. A larger RFB1 consumes less DC current, which is mandatory if light-load efficiency is critical. RFB1 larger than 1 MΩ is not recommended as the feedback path becomes more susceptible to noise. Make sure to route the feedback trace away from the noisy area of the PCB and minimize the feedback node size. Route the feedback trace away from the noisy areas of the PCB and minimize the feedback node size. FB resistors, type 3 ripple injection resistors, or both must be kept close to the device pin.