The power distribution unit (PDU) market is evolving rapidly due to increased electric vehicle (EV) adoption. PDUs manage low-voltage power distribution in vehicles, consolidating connections and protecting circuits in a compact design.
Key trends include the use of 12 and 48 V systems, replacing traditional fuses with e-fuses, and shifting secondary power distribution to zonal architectures.
A power distribution system supplies and manages electrical power throughout the vehicle. It includes a power rail switch unit (PRS), connecting multiple power sources, a primary PDU distributing power via e-fused channels, and secondary units like ZCUs that handle localized distribution and control, reducing wiring complexity by handling secondary power distribution and control closer to the loads such as lights and sensors.
The AEK-POW-PDUMINI PDU evaluation board aligns with this market trend. It can function as a secondary power distribution unit, closer to the loads, reducing the wire total length, within the zone control unit.
This integration optimizes the power distribution wire harness and the in-vehicle network (IVN).
The AEK-POW-PDUMINI board can also serve as a building block for complex primary PDUs.
The on-board high-side drivers have integrated smart e-fuses with a current threshold configurable via SPI to block the channel current drain at a given level.
These latest generation, regenerable, configurable, and precise smart fuses replace standard discrete fuses.
A key feature is STi2Fuse protection (STMicroelectronics’ proprietary I²t functionality), an intelligent circuit breaking mechanism designed to protect PCB traces, connectors, and wire harnesses from overheating, without impacting load transients such as inrush currents and capacitance charging.
The protection is embedded in the eFuse devices and does not require MCU intervention for the calculation, thus saving a lot of BOM in the complete system.
The I²t curve parameters can be individually configured for each channel. The dissipated power is limited to a safe level, up to the point of thermal shutdown intervention.
The device enters a fail-safe mode in case of communication loss with the microcontroller, reset of digital memory, or watchdog monitoring time-out event. In fail-safe mode, the output can be directly controlled by dedicated, assignable direct inputs.
To meet the highest automotive safety standards, all eFuse devices include a periodic watchdog operating within a defined time window.
The board operates in three modes: assembly mode, related to vehicle assembly, park mode, related to the vehicle parking state, where the system power consumption is minimized, and running mode, related to the vehicle driving state.
In park mode, the following events trigger a wake-up from standby for the system: a wake-up by a CAN message, current requested on a L99SP08 P-channel above the threshold, or periodic wake-up for active channel monitoring.
The wake-up signal is managed by the SPSB081 PMIC which subsequently wakes the MCU. The MCU then determines the reason for the wake-up and acts accordingly.
Run mode represents the normal operation mode for the PDU system. Once started, the MCU uses its internal NVM configuration to configure and turn on the channels according to the given order and timing. Upon completion, status feedback is provided to other ECUs via CAN communication.
Eight out of 10 high-side driver channels on the AEK-POW-PDUMINI are connected to L99SP08 P-channel outputs. The remaining two channels are independent.
In standby mode (for example, car in park mode), the eight main output channels are switched off, while the coupled L99SP08 P-channels are turned on.
When the power demand exceeds the programmable threshold, the process is reversed: the eight main output channels are turned on, and the P-channels are switched off. This behavior is applicable to any of the eight channels independently.
The board features two power supplies (5 and 3.3 V), provided by a DC-DC converter for higher current capability and an LDO for low current capability but higher precision.
The main AEK-POW-PDUMINI board connector is a 96-pin plug-and-play automotive unified connector dedicated to the MCU.
This connector allows the board to connect to an AEK-MCU-C4LIT3 MCU board, enabling power delivery control through CAN-FD. In the current software implementation, the AEK-POW-PDUMINI board can be addressed via CAN commands, including the diagnostic portion that is implemented based on a stripped version of ISO14229 – UDS protocol.
Finally, the AEK-POW-PDUMINI is a functional block of the AutoDevKit ecosystem, which includes dedicated demos to simplify board configuration and usage.
