Infineon AUIR3241STR High-Side Switch: Datasheet, Application Circuit, and Design Guide

The Infineon AUIR3241STR is a robust and intelligent high-side power switch designed to drive a wide range of resistive, inductive, and capacitive loads. Engineered with the proprietary SMART7 technology, this device integrates advanced protection and diagnostic features, making it an ideal solution for demanding automotive and industrial applications such as driving solenoids, valves, lamps, and motors.

Datasheet Overview and Key Features

The datasheet for the AUIR3241STR reveals a highly integrated component housed in a PG-DSO-8-47 (DPAK) package, which offers excellent thermal performance. Its core electrical characteristics include a 40V load supply voltage capability and a continuous output current of up to 1.7A. The device operates from a low-voltage logic supply (VCC) from 5.5V to 28V, making it compatible with standard microcontrollers and logic circuits.

Key features that set this switch apart are its comprehensive suite of integrated protections:

Over-Current Protection (OCL): The device features cycle-by-cycle current limiting to protect itself and the load during short-circuit events.

Over-Temperature Protection (OTSD): An internal temperature sensor shuts down the output if the junction temperature exceeds a critical threshold, restarting automatically upon cooling.

Over-Voltage Protection (CLAMP): An integrated active clamp handles inductive load turn-off by dissipating the energy, protecting the switch from voltage spikes.

Load Current Feedback: A proportional (IPROPI) current sense pin provides a ground-referenced analog voltage signal proportional to the load current, enabling sophisticated diagnostics and closed-loop control without the need for a external shunt resistor.

Loss of Ground and Loss of VCC Protection: The device remains safe and controlled even in the event of faulty wiring conditions.

Typical Application Circuit

The implementation of the AUIR3241STR is remarkably straightforward, requiring very few external components. A standard application circuit consists of:

1. The AUIR3241STR IC.

2. A microcontroller (MCU) that provides the input control signal (IN) and monitors the current feedback (IPROPI).

3. A decoupling capacitor (typically 100nF) placed close to the VCC and GND pins.

4. The load (e.g., a solenoid, lamp, small motor) connected between the OUT pin and ground.

5. An optional capacitor on the IPROPI pin to filter the analog feedback signal.

The MCU drives the IN pin high (typically > 3.3V) to turn the switch on and low to turn it off. The status of the load and the health of the system can be continuously monitored by reading the analog voltage on the IPROPI pin.

Essential Design Guide and Considerations

To ensure reliable operation, several design aspects must be considered:

Thermal Management: Although the integrated protections are robust, the package's power dissipation must be calculated. The maximum sustainable current is often limited by the allowable temperature rise of the junction. Proper PCB layout with a sufficient copper area for the DPAK tab is critical to act as a heat sink.

Inductive Load Handling: The internal active clamp is designed to manage most inductive kickback. However, for highly inductive loads, verifying the energy dissipation against the device's capabilities is necessary.

Current Sense Calibration: The IPROPI gain (KILIS) is specified in the datasheet. The system's microcontroller ADC must be calibrated to accurately convert the IPROPI voltage into load current values for diagnostics.

EMC Considerations: Good PCB layout practices are essential. This includes keeping high-current paths short and tight, placing the decoupling capacitor as close as possible to the VCC and GND pins, and separating analog (IPROPI) and digital (IN) traces.

ICGOOODFIND

The Infineon AUIR3241STR stands out as an exceptionally reliable and feature-rich high-side switch. Its integration of robust protection mechanisms, precise diagnostic feedback via the IPROPI pin, and minimal external component requirement significantly simplifies design complexity, reduces board space, and enhances system reliability. It is a superior choice for designers seeking to build advanced, fault-resistant power control systems in harsh electrical environments.

Keywords: High-Side Switch, SMART7 Technology, Over-Current Protection, Current Sense Feedback (IPROPI), Automotive Grade.