ZHCSGO2H September 2003 – November 2018 LM5007
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 Detailed Description
-
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 Custom Design With WEBENCH® Tools
- 8.2.2.2 Custom Design With Excel Quickstart Tool
- 8.2.2.3 Feedback Resistors, RFB1 and RFB2
- 8.2.2.4 Switching Frequency Selection, RON
- 8.2.2.5 Buck Inductor, L1
- 8.2.2.6 Output Capacitor, COUT
- 8.2.2.7 Type I Ripple Circuit, RC
- 8.2.2.8 Input Capacitor, CIN
- 8.2.2.9 Current Limit, RCL
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文档支持
- 12机械、封装和可订购信息
8.2.2.8 Input Capacitor, CIN
The input capacitor should be large enough to limit the input voltage ripple that can be calculated using Equation 14.
The input ripple reaches its maximum at D = 0.5. Targeting a ΔVCIN = 0.5 V at using a duty cycle of D = 0.5 results in CIN = 0.526 µF. A standard value of 1 µF is selected. The input capacitor should be rated for the maximum input voltage under all conditions. A 100-V, X7R type capacitor is selected for this design. The input capacitor should be placed close to the VIN pin and the anode of the diode (D1) as it supplies high-frequency switching current.
Also place a 0.1-µF bypass capacitor (CBYP) very close to VIN and RTN pins of the IC to reduce switching power loop parasitic inductance and mitigate SW node overshoot and ringing.