ZHCSB48B May 2013 – January 2019 TPS55330
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 Selecting the Switching Frequency (R4)
- 8.2.2.3 Determining the Duty Cycle
- 8.2.2.4 Selecting the Inductor (L1)
- 8.2.2.5 Computing the Maximum Output Current
- 8.2.2.6 Selecting the Output Capacitor (C8-C10)
- 8.2.2.7 Selecting the Input Capacitors (C2, C7)
- 8.2.2.8 Setting Output Voltage (R1, R2)
- 8.2.2.9 Setting the Soft-start Time (C7)
- 8.2.2.10 Selecting the Schottky Diode (D1)
- 8.2.2.11 Compensating the Control Loop (R3, C4, C5)
- 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
8.2.2.5 Computing the Maximum Output Current
The over-current limit for the integrated power MOSFET limits the maximum input current and thus the maximum input power for a given input voltage. Maximum output power is less than maximum input power due to power conversion losses. Therefore, the current limit setting, input voltage, output voltage and efficiency can all change maximum current output (IOUTmax). The current limit clamps the peak inductor current, therefore the ripple has to be subtracted to derive maximum DC current. Decreasing the KIND or designing for a higher efficiency will increase the maximum output current. This can be evaluated with the chosen inductance or the chosen KIND. This should be evaluated with the minimum input voltage and minimum peak current limit (ILIM) of 5.25 A.
In this design with 2.9 V input boosted to 5 V output and a 2.2 μH inductor with an assumed the Schottky forward voltage of 0.5 V and estimated efficiency of 80%, the maximum output current is 2.25 A. With the 4.2 V input and increased estimated efficiency of 90%, the maximum output current increases to 3.68 A.