ZHCSB50K December 2012 – May 2019 TPS50301-HT
PRODUCTION DATA.
- 1 特性
- 2 应用
- 3 说明
- 4 修订历史记录
- 5 说明 （续）
- 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 VIN and Power VIN Pins (VIN and PVIN)
- 8.3.2 PVIN vs Frequency
- 8.3.3 Voltage Reference
- 8.3.4 Adjusting the Output Voltage
- 8.3.5 Maximum Duty Cycle Limit
- 8.3.6 PVIN vs Frequency
- 8.3.7 Safe Start-Up into Prebiased Outputs
- 8.3.8 Error Amplifier
- 8.3.9 Slope Compensation
- 8.3.10 Enable and Adjust UVLO
- 8.3.11 Adjustable Switching Frequency and Synchronization (SYNC)
- 8.3.12 Slow Start (SS/TR)
- 8.3.13 Power Good (PWRGD)
- 8.3.14 Bootstrap Voltage (BOOT) and Low Dropout Operation
- 8.3.15 Sequencing (SS/TR)
- 8.3.16 Output Overvoltage Protection (OVP)
- 8.3.17 Overcurrent Protection
- 8.3.18 TPS50301-HT Thermal Shutdown
- 8.3.19 Turn-On Behavior
- 8.3.20 Small Signal Model for Loop Response
- 8.3.21 Simple Small Signal Model for Peak Current Mode Control
- 8.3.22 Small Signal Model for Frequency Compensation
- 8.4 Device Functional Modes
-
9 Application and Implementation
- 9.1 Application Information
- 9.2
Typical Application
- 9.2.1 Design Requirements
- 9.2.2
Detailed Design Procedure
- 9.2.2.1 Custom Design With WEBENCH® Tools
- 9.2.2.2 Operating Frequency
- 9.2.2.3 Output Inductor Selection
- 9.2.2.4 Output Capacitor Selection
- 9.2.2.5 Input Capacitor Selection
- 9.2.2.6 Slow Start Capacitor Selection
- 9.2.2.7 Bootstrap Capacitor Selection
- 9.2.2.8 Undervoltage Lockout (UVLO) Set Point
- 9.2.2.9 Output Voltage Feedback Resistor Selection
- 9.2.2.10 Compensation Component Selection
- 9.2.3 Parallel Operation
- 9.2.4 Application Curve
- 10Power Supply Recommendations
- 11Layout
- 12器件和文档支持
- 13机械、封装和可订购信息
8.3.12 Slow Start (SS/TR)
The device uses the lower voltage of the internal voltage reference or the SS/TR pin voltage as the reference voltage and regulates the output accordingly. A capacitor on the SS/TR pin to ground implements a slow-start time. The device has an internal pullup current source of 5 mA that charges the external slow-start capacitor. Equation 7 shows the calculations for the slow-start time (Tss, 10% to 90%) and slow-start capacitor (Css). The voltage reference (Vref) is 0.795 V and the slow-start charge current (Iss) is 2.5 μA.
When the input UVLO is triggered, the EN pin is pulled below 1.032 V, or a thermal shutdown event occurs the device stops switching and enters low current operation. At the subsequent power-up, when the shutdown condition is removed, the device does not start switching until it has discharged its SS/TR pin to ground ensuring proper soft-start behavior.