Infineon AUIR3240STR High-Side Switch: Datasheet, Application Circuit, and Design Guide
The Infineon AUIR3240STR is a robust and intelligent high-side power switch designed to drive a wide range of resistive and inductive loads, such as solenoids, valves, motors, and lamps, in the harsh environment of automotive applications. This device integrates advanced protection and diagnostic features, making it a cornerstone for building reliable and efficient electronic control units (ECUs).
Datasheet Overview: Key Specifications and Features
The AUIR3240STR is built using Infineon's proprietary SMART7 technology. It is a protected single-channel high-side switch housed in a compact and thermally efficient D²PAK-7 (TO-263-7) surface-mount package. Its key electrical characteristics include:
Output Current: A continuous current capability of up to 11 A.
Load Voltage: Operates with a supply voltage (VS) from a typical 5.5V up to a maximum of 50 V, comfortably covering 12V and 24V automotive systems.
On-State Resistance (RDS(on)): A very low typical RDS(on) of 17 mΩ, which minimizes power dissipation and heat generation.
Control Interface: Features a 3.3V / 5V logic-level compatible input pin, allowing for direct connection to microcontrollers (MCUs) without the need for level-shifting circuitry.
Beyond its switching capabilities, the device is renowned for its comprehensive suite of integrated protection and diagnostic functions:
Over-Current Shutdown with Active Current Limiting: Protects the device and the load during short-circuit events.
Over-Temperature Shutdown: Turns the output off if the junction temperature exceeds the critical limit (typically 165°C) and automatically restarts once it has cooled down.
Over-Voltage Clamp: Protects the switch from voltage transients on the supply line (e.g., load dump).
Ground Loss and Supply Loss Protection: Ensures predictable behavior if the ground connection or supply voltage is interrupted.
Open Load Detection in Off-State: Diagnoses a missing load when the switch is commanded off.
Diagnostic Feedback: The status output pin provides a digital signal to the MCU, indicating fault conditions such as over-temperature or open load.
Application Circuit
The typical application circuit for the AUIR3240STR is remarkably simple, a testament to its high level of integration.
1. The input pin (IN) is connected directly to a GPIO pin of a microcontroller.
2. The output pin (OUT) is connected to the load.
3. The other terminal of the load is connected to ground.
4. A supply decoupling capacitor (e.g., 100 nF) should be placed as close as possible between the VS pin and ground.
5. For inductive loads, a flyback diode may be required in parallel with the load, though the internal architecture provides effective clamping for most transient events.
6. The status pin (ST) is connected to another GPIO on the MCU to read the diagnostic feedback.
Design Guide and Considerations
1. Thermal Management: Despite its low RDS(on), power dissipation (I² RDS(on)) is critical at high currents. The PCB layout must utilize a sufficient copper area connected to the device's tab to act as a heatsink. Thermal vias should be used to transfer heat to inner or bottom layers.
2. Inductive Load Clamping: The internal clamp handles most energy from inductive turn-off. However, for highly inductive loads, verify that the single-pulse avalanche energy rating is not exceeded.
3. Diagnostic Interpretation: The MCU software must correctly interpret the status pin. It is active-low and indicates a fault condition (e.g., over-temperature) only when the input is high and the output is off due to that fault.
4. Inrush Current: Loads like lamps have a very high inrush current (often 10x the steady-state current). The active current limiting feature of the AUIR3240STR manages this effectively, but the thermal design must account for this repeated stress.
5. EMC Compliance: Follow good EMC practices: use short and direct PCB traces for high-current paths, ensure a solid ground plane, and properly decouple the power supply.
The Infineon AUIR3240STR stands out as an exceptionally integrated and robust solution for high-side switching. Its combination of high current handling, low power loss, extensive built-in protection mechanisms, and precise diagnostic feedback significantly simplifies design, reduces component count, and enhances the overall reliability of automotive and industrial systems. It is an optimal choice for designers seeking to minimize system complexity while maximizing performance and safety.
Keywords:
1. High-Side Switch
2. SMART7 Technology
3. Over-Current Protection
4. Diagnostic Feedback
5. Automotive Grade
