ZHCSOO7A August 2021 – November 2021 TPSM8A28 , TPSM8A29
PRODUCTION DATA
- 1 特性
- 2 應用
- 3 說明
- 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 Internal VCC LDO and Using External Bias on VCC Pin
- 7.3.2 Enable
- 7.3.3 Output Voltage Setting
- 7.3.4 Internal Fixed Soft Start and External Adjustable Soft Start
- 7.3.5 External REFIN for Output Voltage Tracking
- 7.3.6 Frequency and Operation Mode Selection
- 7.3.7 D-CAP3? Control
- 7.3.8 Low-Side FET Zero-Crossing
- 7.3.9 Current Sense and Positive Overcurrent Protection
- 7.3.10 Low-Side FET Negative Current Limit
- 7.3.11 Power Good
- 7.3.12 Overvoltage and Undervoltage Protection
- 7.3.13 Out-Of-Bounds (OOB) Operation
- 7.3.14 Output Voltage Discharge
- 7.3.15 UVLO Protection
- 7.3.16 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 Output Voltage Setting Point
- 8.2.2.2 Choose the Inductor
- 8.2.2.3 Set the Current Limit (TRIP)
- 8.2.2.4 Choose the Output Capacitor
- 8.2.2.5 Choose the Input Capacitors (CIN)
- 8.2.2.6 Soft-Start Capacitor (SS/REFIN Pin)
- 8.2.2.7 EN Pin Resistor Divider
- 8.2.2.8 VCC Bypass Capacitor
- 8.2.2.9 BOOT Capacitor
- 8.2.2.10 PGOOD Pullup Resistor
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
7.3.4 Internal Fixed Soft Start and External Adjustable Soft Start
The TPSM8A28 and TPSM8A29 power modules allow both internal fixed soft start and external adjustable soft start. The internal soft-start time is 1.5 ms. The soft-start time can be increased by adding a soft-start (SS) capacitor between the SS/REFIN and VSNS– pins. The total SS capacitor value can be determined by Equation 2. The device follows the longer SS ramp among the internal SS time and the SS time determined by the external SS capacitors.
The device does not require a capacitor from the SS/REFIN pin to AGND, so it is not recommended to place a capacitor from the SS/REFIN pin to AGND. If both CSS/REFIN-to-VSNS– and CSS/REFIN-to-AGND capacitors exist, place CSS/REFIN-to-VSNS– more closely to the shortest trace back to the VSNS– pin.
The SS/REFIN pin is discharged internally during the internal power-on delay to make sure the soft-start ramp always starts from zero.
