ZHCSHW4A December 2017 – January 2019 TPS23523
PRODUCTION DATA.
- 1 特性
- 2 应用
- 3 说明
- 4 修订历史记录
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Parameter Measurement Information
- 8 Detailed Description
-
9 Application and Implementation
- 9.1 Application Information
- 9.2
Typical Application
- 9.2.1 Design Requirements
- 9.2.2
Detailed Design Procedure
- 9.2.2.1 Selecting RSNS
- 9.2.2.2 Selecting Soft Start Setting: CSS and CSS,VEE
- 9.2.2.3 Selecting VDS Switch Over Threshold
- 9.2.2.4 Timer Selection
- 9.2.2.5 MOSFET Selection and SOA Checks
- 9.2.2.6 Input Cap, Input TVS, and OR-ing FET selection
- 9.2.2.7 EMI Filter Consideration
- 9.2.2.8 Undervoltage and Overvoltage Settings
- 9.2.2.9 Choosing RVCC and CVCC
- 9.2.2.10 Power Good Interface to Downstream DC/DC
- 9.2.3 Application Curves
- 10Power Supply Recommendations
- 11Layout
- 12器件和文档支持
- 13机械、封装和可订购信息
9.2.2.4 Timer Selection
The timer determines how long the hot swap can be in current limit before timing out and can be programmed using CTMR. In general a longer time out (TTO) improves ability to ride through voltage steps, brown outs, and other transients. However, a larger setting can also expose the MOSFET to more stress, because it takes longer for the FET to shut down during fault conditions. If there are no specific voltage step or transient requirements, 2 ms is a good starting point. Use the equation below to compute the target CTMR. Choose the next available capacitor value of 15 nF, which results in a 2.25 ms time out.
Equation 16. 