ZHCSLU8A September 2020 – October 2020 TPS51397A
PRODUCTION DATA
- 1 特性
- 2 應用
- 3 說明
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Detailed Description
- 8 Application and Implementation
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
7.3.2 Soft Start
The TPS51397A has an internal 1.2-ms soft start. An external SS pin is provided for setting higher soft-start time if needed. When the EN pin becomes high, the soft-start function begins ramping up the reference voltage to the PWM comparator.
If the application needs a higher soft-start time, it 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 2:
where
- VREF is 0.6 V and ISS is 5 μA