RT9742AGJ5F

Overview

The RT9742AGJ5F is a single-channel high-side power switch IC designed for USB applications. It features an N-MOSFET with a maximum on-resistance of 70 mΩ and a typical value of 55 mΩ. The device supports a continuous output current of 3 A, with fixed current limiting protection. It operates within a supply voltage range of 2.7 V to 6 V. Key electrical parameters include a maximum turn-on time of 2.1 ms and a quiescent current of 0.03 mA. The component is rated for operation between -40°C and +85°C ambient temperature.

Feature Summary

• Integrates comprehensive fault protection including over-current, short circuit fold-back, thermal shutdown, and under-voltage lockout.
• Provides a status flag output to indicate fault conditions to the local controller.
• Includes an embedded delay function to prevent misoperation caused by inrush currents.

Applications

• USB peripheral power switching
• Notebook PC power distribution
• High-side load switching

Procurement Notes

Verify the specific suffix GJ5F corresponds to the TSOT-23-5 (FC) package and tape & reel orientation. Confirm RoHS compliance status and moisture sensitivity level (MSL 3) requirements for your assembly process. Ensure the 3A current rating aligns with your system's peak load demands and thermal management capabilities.

Selection Notes

Select this part when a single-channel high-side switch with integrated protection and status reporting is required. The 3A current capability and low on-resistance make it suitable for powering moderate-load USB devices. Consider the TSOT-23-5 footprint constraints and the need for a flag signal for fault monitoring in your design.

Part Context

The RT9742 series comprises cost-effective, low-voltage power switches optimized for USB interfaces. Variants differ primarily in current ratings (0.5A to 3A) and package types (TSOT-23-5, SOT-23-3). The AGJ5F variant specifically denotes the 3A version in the fine-pitch TSOT-23-5 package.

Replacement Considerations

Other RT9742 variants with different current ratings or packages may serve as substitutes if electrical parameters are compatible. Verify pinout compatibility and thermal performance when replacing with lower-rated models.

FAQ

What is the purpose of the flag output?

The flag output indicates fault conditions, such as over-current or thermal shutdown, to the local USB controller.

How does the device handle inrush current?

An embedded delay function prevents misoperation that could occur due to inrush currents during turn-on.