The **TLE7239SL** is an 8-channel low-side power switch designed primarily for automotive applications. It belongs to Infineon’s **SPIDER (SPI Driver for Enhanced Relay control)** family. It is specifically engineered to drive relays, LEDs, and small motors via a Serial Peripheral Interface (SPI). --- ### 1. Key Technical Specifications | Parameter | Value/Description | | :--- | :--- | | **Channels** | 8 Low-Side Switches | | **Supply Voltage ($V_{bb}$)** | 4.5V to 28V | | **Logic Supply ($V_{dd}$)** | 3.0V to 5.5V | | **Drain-Source ON-Resistance ($R_{DS(on)}$)** | Typ. 0.8 $\Omega$ per channel | | **Nominal Load Current** | 350 mA per channel | | **Interface** | 16-bit SPI (Serial Peripheral Interface) | | **Package** | PG-SSOP-24 (Compact Surface Mount) | --- ### 2. Core Functional Blocks #### A. SPI Interface The device is controlled through a standard 16-bit SPI. This allows for: * **Command Input:** Turning individual channels ON or OFF. * **Status Output:** Reading diagnostic data (Open Load, Short Circuit, Over-temperature). * **Daisy Chain:** Multiple TLE7239SL chips can be linked in series to save MCU pins. #### B. Output Stage (Low-Side) The outputs are N-channel MOSFETs. When a channel is activated, it pulls the load to ground (GND). It includes an integrated **Clamping Structure** to protect against inductive kicks when driving relays. #### C. Protection & Diagnostics The TLE7239SL is "protected," meaning it includes hardware logic to prevent chip failure: * **Overload/Short Circuit Protection:** Limits current or shuts down the channel if a short is detected. * **Over-temperature Shutdown:** Global or channel-specific thermal protection. * **Open Load Detection:** Can sense if a bulb or relay is disconnected while in the OFF state. --- ### 3. Pin Configuration Overview | Pin Name | Function | | :--- | :--- | | **OUT0 - OUT7** | Drain connections of the 8 power MOSFETs. | | **IN0 / IN1** | Direct input pins for PWM control (bypassing SPI latency for 2 channels). | | **CSN, SCK, SI, SO** | Standard SPI communication pins (Chip Select, Clock, Input, Output). | | **RESN** | Reset pin (Active Low) to clear all registers. | | **LHI** | Limp Home Input (Enables specific channels during MCU failure). | --- ### 4. Typical Application Circuit The TLE7239SL acts as the bridge between a low-power Microcontroller (MCU) and high-power automotive loads. ```cpp // Pseudocode for SPI Control void turnOnChannelZero() { // 16-bit command: Address + Data // Example: Sending 0x01 to the output register SPI.transfer16(0x0001); digitalWrite(CSN, HIGH); // Latch data } ``` --- ### 5. Advantages in Automotive Design 1. **Space Efficiency:** Replaces 8 discrete transistors and their driving circuitry with one small SSOP-24 chip. 2. **Safety:** The "Limp Home" feature ensures that critical loads (like basic lighting) stay on even if the communication with the MCU fails. 3. **Low Standby Current:** Optimized for battery-powered systems to prevent drainage when the ignition is off.