ZHCSD91B January 2015 – January 2022 TPS65251-1 , TPS65251-2 , TPS65251-3
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 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 Adjustable Switching Frequency
- 7.3.2 Synchronization
- 7.3.3 Out-of-Phase Operation
- 7.3.4 Delayed Start-Up
- 7.3.5 Soft-Start Time
- 7.3.6 Adjusting the Output Voltage
- 7.3.7 Input Capacitor
- 7.3.8 Bootstrap Capacitor
- 7.3.9 Error Amplifier
- 7.3.10 Slope Compensation
- 7.3.11 Power Good
- 7.3.12 3.3-V and 6.5-V LDO Regulators
- 7.3.13 Current Limit Protection
- 7.3.14 Overvoltage Transient Protection (OVP)
- 7.3.15 Thermal Shutdown
- 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
- 8.2.2.1 Loop Compensation Circuit
- 8.2.2.2 Selecting the Switching Frequency
- 8.2.2.3 Output Inductor Selection
- 8.2.2.4 Output Capacitor
- 8.2.2.5 Input Capacitor
- 8.2.2.6 Soft-Start Capacitor
- 8.2.2.7 Bootstrap Capacitor Selection
- 8.2.2.8 Adjustable Current Limiting Resistor Selection
- 8.2.2.9 Output Voltage and Feedback Resistors Selection
- 8.2.2.10 Compensation
- 8.2.2.11 3.3-V and 6.5-V LDO Regulators
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
8.2.2.10 Compensation
A type-II compensation circuit is adequate for the converter to have a phase margin between 60 and 90 degrees. The following equations show the procedure of designing a peak current mode control dc/dc converter.
The compensation design takes the following steps:
- Set up the anticipated cross-over frequency. In this example, the anticipated cross-over frequency (fc) is 65 kHz. The power stage gain (gmPS ) is 10 A/V and the GM amplifier gain (gM ) is 130 µA/V.
Equation 25.
- Place compensation zero at low frequency to boost the phase margin at the crossover frequency. From the procedures above, the compensation network includes a 20-kΩ resistor (R12) and a 4700-pF capacitor (C1).
- An additional pole can be added to attenuate high frequency noise.
From the procedures above, the compensation network includes a 20-kΩ resistor (R12) and a 4700-pF capacitor (C14).