ZHCSO27B May 2021 – December 2022 TPS7H4002-SP
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 VIN and Power VIN Pins (VIN and PVIN)
- 7.3.2 Voltage Reference
- 7.3.3 Adjusting the Output Voltage
- 7.3.4 Safe Start-Up Into Prebiased Outputs
- 7.3.5 Error Amplifier
- 7.3.6 Slope Compensation
- 7.3.7 Enable and Adjust UVLO
- 7.3.8 Adjustable Switching Frequency and Synchronization (SYNC)
- 7.3.9 Slow Start (SS/TR)
- 7.3.10 Power Good (PWRGD)
- 7.3.11 Sequencing (SS/TR)
- 7.3.12 Output Overvoltage Protection (OVP)
- 7.3.13 Overcurrent Protection
- 7.3.14 Thermal Shutdown
- 7.3.15 Turn-On Behavior
- 7.3.16 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 Operating Frequency
- 8.2.2.2 Output Inductor Selection
- 8.2.2.3 Output Capacitor Selection
- 8.2.2.4 Output Schottky Diode
- 8.2.2.5 Slow Start Capacitor Selection
- 8.2.2.6 Undervoltage Lockout (UVLO) Set Point
- 8.2.2.7 Output Voltage Feedback Resistor Selection
- 8.2.2.8 Compensation Component Selection
- 8.2.3 Parallel Operation
- 8.2.4 Application Curve
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
7.3.9 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. Equation 5 shows the calculations for the slow-start time (tSS, 10% to 90%) and slow-start capacitor (CSS). The voltage reference (VREF) is 0.807 V and the slow-start charge current (ISS) is 2.5 μA.
When any of the following 3 scenarios occur; the input UVLO is triggered, the EN pin is pulled below 1.05 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.