ZHCSAK8J December 2003 – June 2022 TPS40054 , TPS40055 , TPS40057
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 Setting the Switching Frequency (Programming the Clock Oscillator)
- 7.3.2 Programming The Ramp Generator Circuit
- 7.3.3 UVLO Operation
- 7.3.4 BP5 and BP10 Internal Voltage Regulators
- 7.3.5 Programming Soft Start
- 7.3.6 Programming Current Limit
- 7.3.7 Synchronizing to an External Supply
- 7.3.8 Loop Compensation
- 7.4 Device Functional Modes
-
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 Calculate Maximum and Minimum Duty Cycles
- 8.2.2.2 Select Switching Frequency
- 8.2.2.3 Select ΔI
- 8.2.2.4 Calculate the High-Side MOSFET Power Losses
- 8.2.2.5 Calculate Synchronous Rectifier Losses
- 8.2.2.6 Calculate the Inductor Value
- 8.2.2.7 Set the Switching Frequency
- 8.2.2.8 Program the Ramp Generator Circuit
- 8.2.2.9 Calculate the Output Capacitance (CO)
- 8.2.2.10 Calculate the Soft-Start Capacitor (CSS/SD)
- 8.2.2.11 Calculate the Current Limit Resistor (RILIM)
- 8.2.2.12 Calculate Loop Compensation Values
- 8.2.2.13 Calculate the Boost and BP10V Bypass Capacitance
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
8.1.3 Calculating the Boost and BP10 Bypass Capacitor
The BOOST capacitance provides a local, low impedance source for the high-side driver. The BOOST capacitor must be a good quality, high-frequency capacitor. The size of the bypass capacitor depends on the total gate charge of the MOSFET and the amount of droop allowed on the bypass capacitor. The BOOST capacitance is described in Equation 31.
The 10-V reference pin, BP10V provides energy for both the synchronous MOSFET and the high-side MOSFET through the BOOST capacitor. Neglecting any efficiency penalty, the BP10V capacitance is described in Equation 32.
