ZHCS547K January 2010 – February 2018 LM27402
PRODUCTION DATA.
- 1 特性
- 2 應用
- 3 說明
- 4 修訂歷史記錄
- 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 Wide Input Voltage Range
- 7.3.2 UVLO
- 7.3.3 Precision Enable
- 7.3.4 Soft-Start and Voltage Tracking
- 7.3.5 Output Voltage Setpoint and Accuracy
- 7.3.6 Voltage-Mode Control
- 7.3.7 Power Good
- 7.3.8 Inductor-DCR-Based Overcurrent Protection
- 7.3.9 Current Sensing
- 7.3.10 Power MOSFET Gate Drivers
- 7.3.11 Pre-Bias Start-up
- 7.4 Device Functional Modes
-
8 Application and Implementation
- 8.1
Application Information
- 8.1.1 Converter Design
- 8.1.2 Inductor Selection (L)
- 8.1.3 Output Capacitor Selection (COUT)
- 8.1.4 Input Capacitor Selection (CIN)
- 8.1.5 Using Precision Enable
- 8.1.6 Setting the Soft-Start Time
- 8.1.7 Tracking
- 8.1.8 Setting the Switching Frequency
- 8.1.9 Setting the Current Limit Threshold
- 8.1.10 Control Loop Compensation
- 8.1.11 MOSFET Gate Drivers
- 8.1.12 Power Loss and Efficiency Calculations
- 8.2 Typical Applications
- 8.1
Application Information
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文檔支持
- 12機械、封裝和可訂購信息
封裝選項
機械數據 (封裝 | 引腳)
散熱焊盤機械數據 (封裝 | 引腳)
訂購信息
8.1.2 Inductor Selection (L)
The inductor value is determined based on the operating frequency, load current, ripple current, and duty ratio. The selected inductor must have a saturation current rating greater than the peak current limit of the LM27402. To optimize the performance, the inductance is typically selected such that the ripple current, ΔIL, is between 20% and 40% of the rated output current. Figure 27 illustrates the switch voltage and inductor ripple current waveforms. Once the nominal input voltage, output voltage, operating frequency, and desired ripple current are known, the minimum inductance value can be calculated by Equation 2:
Figure 27. Switch Voltage and Inductor Current Waveforms
The peak inductor current at maximum load, IOUT + ΔIL / 2, should be kept adequately below the peak current limit setpoint of the device.