ZHCSFM7C October 2016 – August 2023 TPS568215
PRODUCTION DATA
- 1
- 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 PWM Operation and D-CAP3 Control Mode
- 7.3.2 Eco-mode Control
- 7.3.3 4.7 V LDO and External Bias
- 7.3.4 MODE Selection
- 7.3.5 Soft Start and Pre-biased Soft Start
- 7.3.6 Enable and Adjustable UVLO
- 7.3.7 Power Good
- 7.3.8 Overcurrent Protection and Undervoltage Protection
- 7.3.9 Out-of-Bounds Operation
- 7.3.10 UVLO Protection
- 7.3.11 Thermal Shutdown
- 7.3.12 Output Voltage Discharge
- 7.4 Device Functional Modes
- 8 Application and Implementation
- 9 Device and Documentation Support
- 10Mechanical, Packaging, and Orderable Information
7.3.5 Soft Start and Pre-biased Soft Start
The TPS568215 has an adjustable soft-start time that can be set by connecting a capacitor on SS pin. When the EN pin becomes high, the soft-start charge current (ISS) begins charging the external capacitor (CSS) connected between SS and AGND. The devices tracks the lower of the internal soft-start voltage or the external soft-start voltage as the reference. The equation for the soft-start time (TSS) is shown in Equation 3:
where
- VREF is 0.6 V and ISS is 6 µA
If the output capacitor is pre-biased at startup, the device initiates switching and starts ramping up only after the internal reference voltage becomes greater than the feedback voltage VFB. This scheme ensures that the converters ramp up smoothly into regulation point.