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55mΩ, 3A High-Side Power Switches with Flag

EVB_RT9742AGJ5F

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The RT9742A integrates an over-current protection circuit, a short fold back circuit, a thermal shutdown circuit and an under-voltage lockout circuit for overall protection. Besides, a flag output is vailable to indicate fault conditions to the local USB controller. Furthermore, the chip also integrates an embedded delay function to prevent miss-operation from happening due to inrush-current. The RT9742A is an ideal solution for USB power supply and can support flexible applications since it is available in TSOT-23-5 (FC) package.

Purpose

The RT9742A is a cost-effective, low-voltage, single N-MOSFET high-side Power Switch IC for USB application. This document explains the function and use of the RT9742A evaluation board (EVB), and provides information to enable operation, modification of the evaluation board and circuit to suit individual requirements.


Introduction

General Product Information

The RT9742A integrates an over-current protection circuit, a short fold back circuit, a thermal shutdown circuit and an under-voltage lockout circuit for overall protection. Besides, a flag output is vailable to indicate fault conditions to the local USB controller. Furthermore, the chip also integrates an embedded delay function to prevent miss-operation from happening due to inrush-current. The RT9742A is an ideal solution for USB power supply and can support flexible applications since it is available in TSOT-23-5 (FC) package.


Product Feature

  • 55mΩ (typ.) N-MOSFET Switch
  • Operating Range : 2.7V to 6V
  • Reverse Blocking Current
  • Under Voltage Lockout
  • Deglitched Fault Report (FLG)
  • Thermal Protection with Fold-back
  • Over Current Protection
  • Short Circuit Protection
  • UL Approved−E219878 Technical Document Image Preview
  • Nemko Approved-NO87949

 

Key Performance Summary Table

Key Features

Evaluation Board Number : PCB050_V1

Input Voltage Range

2.7V to 6V

Max Output Current

3A

Default Output Voltage

5V @ VIN = 5V

Default Marking & Package Type

RT9742AGJ5F, TSOT-23-5 (FC)



Bench Test Setup Conditions

Headers Description and Placement

Technical Document Image Preview

Please carefully inspect the EVB IC and external components, comparing them to the following Bill of Materials, to ensure that all components are installed and undamaged. If any components are missing or damaged during transportation, please contact the distributor or send e-mail to evb_service@richtek.com



Test Points

The EVB is provided with the test points and pin names listed in the table below.

Test point/

Pin name

Signal

Comment (expected waveforms or voltage levels on test points)

VIN

Input voltage

Power input. Support 2.7V to 6V Input Voltage.

EN

Enable test point

High = Enable. Apply a voltage exceeds than enable logic high voltage (2V) for chip enable.

GND

Ground

Ground.

VOUT

Output voltage

Output voltage pin. Probe this pin to observe the output voltage waveform.

/FLG

Fault FLAG Output

FLAG output indicator pin. FLAG is a low active output. Once the over current, short circuit, and over temperature occurring, it will indicate “LOW” after 10ms delay time.



Power-up & Measurement Procedure

1. Connecting input power (2.7V < VIN < 6V) and input ground to VIN and GND test pins respectively.

2. Connecting positive end and negative terminals of load to VOUT and GND test pins respectively.

3. There is a 3-pin header “EN” for enable control. To use a jumper at “HI” option to tie EN test pin to input power VIN for enabling the device. Inversely, to use a jumper at “LO” option to tie EN test pin and ground GND for disabling the device.

4. Connecting an external load up to 5A to the VOUT and GND terminals and verify the over current protection and FLAG indication.


Schematic, Bill of Materials & Board Layout

EVB Schematic Diagram

Technical Document Image Preview



Bill of Materials

Reference

Qty

Part Number

Description

Package

Manufacture

U1

1

RT9742AGJ5F

Power Switch with Flag

TSOT-23-5 (FC)

RICHTEK

CIN

1

10µF/10V/X7R/0805

C-0805

COUT

1

0.1μF/50V/X7R/0805

C-0805

C1, C2

2

NC

J1

1

SIP-3P

SIP-3P

R1

1

10kΩ/0603

R-0603

R3

1

100kΩ/0603

R-0603

R2

1

NC

GP1, GP2, GP3, GP4

4

VIN, GND, VOUT, GND (Gold Pin)

SIP-1P

TP1, TP2, TP3

3

VIN-S, VOUT-S, /FLG (Test Pin)

SIP-1P



PCB Layout

Technical Document Image Preview

Top View

Technical Document Image Preview

Bottom View

Title Last Update Share Download
Evaluation Board User Guide 2015/10/27
Bill of Materials 2015/10/30
Gerber File 2015/10/27
Schematic 2015/10/27
RT9742

70mΩ/55mΩ, 3A/2.5A/2A/1.5A/1A/0.5A 高端功率开关

RT9742

RT9742 是用于 USB 应用的低成本、低压高端功率开关,同时具备低导通电阻和低电流消耗的特性。
它集成了过流保护电路、短路折返电路、热关机保护电路和欠压锁定电路以实现所有的保护功能,还集成了延时功能以防止冲击电流所造成的误操作。它是 USB 电源应用的理想选择,也同时支持其它灵活的应用,其封装为 TSOT-23-5、TSOT-23-5 (FC)与SOT-23-3。

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