ZHCSFE2A August 2016 – November 2017 LM5161-Q1
PRODUCTION DATA.
- 1 特性
- 2 應(yīng)用
- 3 說(shuō)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 Control Circuit
- 7.3.2 VCC Regulator
- 7.3.3 Regulation Comparator
- 7.3.4 Soft-Start
- 7.3.5 Error Transconductance (GM) Amplifier
- 7.3.6 On-Time Generator
- 7.3.7 Current Limit
- 7.3.8 N-Channel Buck Switch and Driver
- 7.3.9 Synchronous Rectifier
- 7.3.10 Enable / Undervoltage Lockout (EN/UVLO)
- 7.3.11 Thermal Protection
- 7.3.12 Ripple Configuration
- 7.4 Device Functional Modes
-
8 Applications and Implementation
- 8.1 Application Information
- 8.2
Typical Applications
- 8.2.1
LM5161-Q1 Synchronous Buck (15-V to 95-V Input, 12-V Output, 1-A Load)
- 8.2.1.1 Design Requirements
- 8.2.1.2
Detailed Design Procedure
- 8.2.1.2.1 Custom Design With WEBENCH® Tools
- 8.2.1.2.2 Output Resistor Divider Selection
- 8.2.1.2.3 Frequency Selection
- 8.2.1.2.4 Inductor Selection
- 8.2.1.2.5 Output Capacitor Selection
- 8.2.1.2.6 Series Ripple Resistor - RESR (FPWM = 1)
- 8.2.1.2.7 VCC and Bootstrap Capacitor
- 8.2.1.2.8 Input Capacitor Selection
- 8.2.1.2.9 Soft-Start Capacitor Selection
- 8.2.1.2.10 EN/UVLO Resistor Selection
- 8.2.1.3 Application Curves
- 8.2.2 LM5161-Q1 Isolated Fly-Buck (36-V to 72-V Input, 12-V, 12-W Isolated Output)
- 8.2.1
LM5161-Q1 Synchronous Buck (15-V to 95-V Input, 12-V Output, 1-A Load)
- 8.3 Do's and Don'ts
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文檔支持
- 12機(jī)械、封裝和可訂購(gòu)信息
封裝選項(xiàng)
機(jī)械數(shù)據(jù) (封裝 | 引腳)
- PWP|14
散熱焊盤機(jī)械數(shù)據(jù) (封裝 | 引腳)
- PWP|14
訂購(gòu)信息
7.3.6 On-Time Generator
The ON-time of the LM5161-Q1 high-side FET is determined by the RON resistor and is inversely proportional to the input voltage (VIN). The inverse relationship with VIN results in a nearly constant frequency as VIN is varied. The ON-time can be calculated from Equation 3 with RON expressed in ohms.
To set a specific continuous conduction mode switching frequency (FSW expressed in Hz), the RON resistor is determined from Equation 4:
RON must be selected for a minimum on-time (at maximum VIN) greater than 150 ns for proper operation. This minimum ON-time requirement limits the maximum switching frequency of applications with relatively high VIN and low VOUT.