ZHCSB84F November 2011 – November 2021 TPS62130 , TPS62130A , TPS62131 , TPS62132 , TPS62133
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Device Comparison Table
- 6 Pin Configuration and Functions
- 7 Specifications
- 8 Detailed Description
- 9 Application and Implementation
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
9.2.2.2.2.3 Soft-Start Capacitor
A capacitance connected between the SS/TR pin and AGND allows a user-programmable start-up slope of the output voltage. A constant current source supports 2.5 µA to charge the external capacitance. The capacitor required for a given soft-start ramp time for the output voltage is given by:
where
- CSS is the capacitance (F) required at the SS/TR pin.
- tSS is the desired soft-start ramp time (s).
DC Bias effect: High capacitance ceramic capacitors have a DC Bias effect, which will have a strong influence on the final effective capacitance. Therefore the right capacitor value has to be chosen carefully. Package size and voltage rating in combination with dielectric material are responsible for differences between the rated capacitor value and the effective capacitance.