ZHCSJF8F December 2008 – April 2019 TPS61175
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 Determining the Duty Cycle
- 8.2.2.3 Selecting the Inductor
- 8.2.2.4 Computing the Maximum Output Current
- 8.2.2.5 Setting Output Voltage
- 8.2.2.6 Setting the Switching Frequency
- 8.2.2.7 Setting the Soft-Start Time
- 8.2.2.8 Selecting the Schottky Diode
- 8.2.2.9 Selecting the Input and Output Capacitors
- 8.2.2.10 Compensating the Small Signal Control Loop
- 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
8.2.2.4 Computing the Maximum Output Current
The over-current limit for the integrated power FET 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 the maximum current output (IOUT(MAX)). The current limit clamps the peak inductor current, therefore the ripple has to be subtracted to derive maximum DC current.
where
- ILIM = overcurrent limit
- ηest= efficiency estimate based on similar applications or computed above
For instance, when VIN = 12 V is boosted to VOUT = 24 V, the inductor is 10 µH, the Schottky forward voltage is 0.4 V, and the switching frequency is 1.2 MHz; then the maximum output current is 1.2 A in typical condition, assuming 90% efficiency and a %RPL = 20%.