ZHCSL48 April 2020 LM5181-Q1
PRODUCTION DATA.
- 1 特性
- 2 应用
- 3 说明
- 4 修订历史记录
- 5 说明 （续）
- 6 Pin Configuration and Functions
- 7 Specifications
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3
Feature Description
- 8.3.1 Integrated Power MOSFET
- 8.3.2 PSR Flyback Modes of Operation
- 8.3.3 Setting the Output Voltage
- 8.3.4 Control Loop Error Amplifier
- 8.3.5 Precision Enable
- 8.3.6 Configurable Soft Start
- 8.3.7 External Bias Supply
- 8.3.8 Minimum On-Time and Off-Time
- 8.3.9 Overcurrent Protection
- 8.3.10 Thermal Shutdown
- 8.4 Device Functional Modes
-
9 Application and Implementation
- 9.1 Application Information
- 9.2
Typical Applications
- 9.2.1
Design 1: Wide VIN, Low IQ PSR Flyback Converter Rated at 5 V, 0.5 A
- 9.2.1.1 Design Requirements
- 9.2.1.2
Detailed Design Procedure
- 9.2.1.2.1 Custom Design With WEBENCH® Tools
- 9.2.1.2.2 Custom Design With Excel Quickstart Tool
- 9.2.1.2.3 Flyback Transformer – T1
- 9.2.1.2.4 Flyback Diode – DFLY
- 9.2.1.2.5 Zener Clamp Circuit – DF, DCLAMP
- 9.2.1.2.6 Output Capacitor – COUT
- 9.2.1.2.7 Input Capacitor – CIN
- 9.2.1.2.8 Feedback Resistor – RFB
- 9.2.1.2.9 Thermal Compensation Resistor – RTC
- 9.2.1.2.10 UVLO Resistors – RUV1, RUV2
- 9.2.1.2.11 Soft-Start Capacitor – CSS
- 9.2.2 Application Curves
- 9.2.1
Design 1: Wide VIN, Low IQ PSR Flyback Converter Rated at 5 V, 0.5 A
- 10Power Supply Recommendations
- 11Layout
- 12器件和文档支持
- 13机械、封装和可订购信息
6 Pin Configuration and Functions
NGU Package
8-Pin WSON With Wettable Flanks
Top View
Pin Functions
| PIN | I/O(1) | DESCRIPTION | |
|---|---|---|---|
| NO. | NAME | ||
| 1 | SW | P | Switch node that is internally connected to the drain of the N-channel power MOSFET. Connect to the primary-side switching terminal of the flyback transformer. |
| 2 | FB | I | Primary-side feedback pin. Connect a resistor from FB to SW. The ratio of the FB resistor to the resistor at the RSET pin sets the output voltage. |
| 3 | VIN | P/I | Input supply connection. Source for internal bias regulators and input voltage sensing pin. Connect directly to the input supply of the converter with short, low impedance paths. |
| 4 | EN/UVLO | I | Enable input and undervoltage lockout (UVLO) programming pin. If the EN/UVLO voltage is below 1.1 V, the converter is in shutdown mode with all functions disabled. If the EN/UVLO voltage is greater than 1.1 V and below 1.5 V, the converter is in standby mode with the internal regulator operational and no switching. If the EN/UVLO voltage is above 1.5 V, the start-up sequence begins. |
| 5 | SS/BIAS | I | Soft start or bias input. Connect a capacitor from SS/BIAS to GND to adjust the output start-up time and input inrush current. If SS/BIAS is left open, the internal 6-ms soft-start timer is activated. Connect an external supply to SS/BIAS to supply bias to the internal voltage regulator and enable internal soft start. |
| 6 | TC | I | Temperature compensation pin. Tie a resistor from TC to RSET to compensate for the temperature coefficient of the forward voltage drop of the secondary diode, thus improving regulation at the secondary-side output. |
| 7 | RSET | I | Reference resistor tied to GND to set the reference current for FB. Connect a 12.1-kΩ resistor from RSET to GND. |
| 8 | GND | G | Analog and power ground. Ground connection of internal control circuits and power MOSFET. |
| - | DAP | G | Die attach pad. Connect to PCB ground plane. |
(1) P = Power, G = Ground, I = Input, O = Output.