ZHCSE52B September 2015 – May 2019 TPS57140-EP
PRODUCTION DATA.
- 1 特性
- 2 应用范围
- 3 说明
- 4 修订历史记录
- 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 Fixed Frequency PWM Control
- 7.3.2 Slope-Compensation Output Current
- 7.3.3 Bootstrap Voltage (Boot)
- 7.3.4 Low-Dropout Operation
- 7.3.5 Error Amplifier
- 7.3.6 Voltage Reference
- 7.3.7 Adjusting the Output Voltage
- 7.3.8 Enable and Adjusting UVLO
- 7.3.9 Slow-Start or Tracking Pin (SS/TR)
- 7.3.10 Overload Recovery Circuit
- 7.3.11 Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
- 7.3.12 Overcurrent Protection and Frequency Shift
- 7.3.13 Selecting the Switching Frequency
- 7.3.14 How to Interface to RT/CLK Pin
- 7.3.15 Power Good (PWRGD Pin)
- 7.3.16 Overvoltage Transient Protection (OVTP)
- 7.3.17 Thermal Shutdown
- 7.3.18 Small-Signal Model for Loop Response
- 7.3.19 Simple Small-Signal Model for Peak-Current-Mode Control
- 7.3.20 Small-Signal Model for Frequency Compensation
- 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 Selecting the Switching Frequency
- 8.2.2.2 Output Inductor Selection (LO)
- 8.2.2.3 Output Capacitor
- 8.2.2.4 Catch Diode
- 8.2.2.5 Input Capacitor
- 8.2.2.6 Slow-Start Capacitor
- 8.2.2.7 Bootstrap Capacitor Selection
- 8.2.2.8 UVLO Set Point
- 8.2.2.9 Output Voltage and Feedback Resistors Selection
- 8.2.2.10 Compensation
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文档支持
- 12机械、封装和可订购信息
7.3.18 Small-Signal Model for Loop Response
Figure 39 shows an equivalent model for the TPS57140-EP control loop which the designer can model in a circuit-simulation program to check frequency response and dynamic load response. The error amplifier is a transconductance amplifier with a gmEA of 97 μS. The designer can model the error amplifier using an ideal voltage-controlled current source. Resistor Ro and capacitor Co model the open-loop gain and frequency response of the amplifier. The 1-mV ac voltage source between nodes a and b effectively breaks the control loop for the frequency-response measurements. Plotting c / a shows the small-signal response of the frequency compensation. Plotting a / b shows the small-signal response of the overall loop. The designer can check the dynamic loop response in a time-domain analysis by replacing RL with a current source having the appropriate load-step amplitude and step rate. This equivalent model is only valid for CCM designs.
Figure 39. Small-Signal Model for Loop Response