TPS929240-Q1 is an automotive, 24-channel LED driver with FlexWire interface to address increasing requirements for individual control of each LED string. Each of the device channels can support both analog dimming and pulse-width-modulation (PWM) dimming, configured through its FlexWire serial interface. The internal electrically erasable programmable read-only memory (EEPROM) allows users to configure device in the scenario of communication loss to fulfill system level safety requirements.

The FlexWire interface is a robust address-based master-slave interface with flexible baud rate. The interface is based on multi-frame universal, asynchronous, receiver-transmitter (UART) protocol. The unique synchronization frame of FlexWire reduces system cost by saving external crystal oscillators. It also supports various physical layer with the help of external physical layer transceiver such as CAN or LIN transceivers. The embedded CRC correction is able to ensure robust communication in automotive environments. The FlexWire interface is easily supported by most of MCUs in the markets.

Each output is a constant current source with individually programmable current output and PWM duty cycle. PWM phase shift is supported for the output channels to improve the EMC performance and reduce the output noise. Each channel features various diagnostics including LED open-circuit, short-circuit and single-LED short-circuit detection. The on-chip analog-digital convertor (ADC) allows the controller to real-time monitor loading conditions.

To further increase robustness, the unique fail-safe of the device state machine allows automatic switching to FAIL-SAFE states in the case of communication loss, for example, MCU failure. The device supports programming fail-safe settings with user-programmable EEPROM. In FAIL-SAFE states, the device supports different configurations if output fails, such as one-fails-all-fail or one-fails-others-on. Each channel can be independently programmed as on or off in FAIL-SAFE states. The FAIL-SAFE state machine also allows the system to function with pre-programmed EEPROM settings without presence of any controller in the system, also known as stand-alone operation.

The microcontroller can access each of the devices through the FlexWire interface. By setting and reading back the registers, the master, which is the microcontroller, has full control over the device and LEDs. All EEPROMs are pre-programmed to default values. TI recommends that users program the EEPROM at the end-of-line for application-specific settings and FAIL-SAFE configurations.