ZHCSTL7I February 2007 – November 2023 LM5116
PRODUCTION DATA
- 1
- 1 特性
- 2 應用
- 3 說明
- 4 Pin Configuration and Functions
- 5 Specifications
- 6 Detailed Description
-
7 Application and Implementation
- 7.1 Application Information
- 7.2
Typical Application
- 7.2.1 Design Requirements
- 7.2.2
Detailed Design Procedure
- 7.2.2.1 Custom Design with WEBENCH? Tools
- 7.2.2.2 Timing Resistor
- 7.2.2.3 Output Inductor
- 7.2.2.4 Current Sense Resistor
- 7.2.2.5 Ramp Capacitor
- 7.2.2.6 Output Capacitors
- 7.2.2.7 Input Capacitors
- 7.2.2.8 VCC Capacitor
- 7.2.2.9 Bootstrap Capacitor
- 7.2.2.10 Soft Start Capacitor
- 7.2.2.11 Output Voltage Divider
- 7.2.2.12 UVLO Divider
- 7.2.2.13 MOSFETs
- 7.2.2.14 MOSFET Snubber
- 7.2.2.15 Error Amplifier Compensation
- 7.2.2.16 Comprehensive Equations
- 7.2.3 Application Curves
- 7.3 Power Supply Recommendations
- 7.4 Layout
- 8 Device and Documentation Support
- 9 Revision History
- 10Mechanical, Packaging, and Orderable Information
7.2.2.5 Ramp Capacitor
With the inductor and sense resistor value selected, the value of the ramp capacitor (CRAMP) necessary for the emulation ramp circuit is:
Equation 33.
where
- L is the value of the output inductor in Henrys
- gm is the ramp generator transconductance (5 μA/V)
- A is the current sense amplifier gain (10 V/V)
For the 5-V output design example, the ramp capacitor is calculated as:
Equation 14.
The next lowest standard value of 270 pF was selected for CRAMP. TI recommends a COG-type capacitor with 5% or better tolerance.