Exploding global electric-vehicle (EV) demand is driving innovation that, in turn, is accelerating battery-system development for automotive applications. For example, a 48-V battery system can provide the necessary power to operate mild hybrid electric vehicles (MHEVs), electric trucks, and electric motorcycles.
Such Li-ion battery systems need to be protected against negative and positive voltages. In addition, these batteries must be able to quickly and reliably disconnect from loads in the event of an overcurrent. Since a battery unit may not be dedicated to one vehicle, status diagnostic and protection threshold configurability also are essential.
To address these requirements, Infineon Technologies introduced the EiceDRIVER 2ED4820-EM N-channel MOSFET gate driver. With two outputs controlled via a Serial Peripheral Interface (SPI), it provides full duplex communication at very high speeds, and can handle configuration, diagnosis, and control of high-current 48-V automotive applications.
Driver Details
The new gate driver includes a current-sense amplifier for high- or low-side measurement. The low-side measurement helps reduce cost, PCB space, and overall power dissipation since the existing shunt resistor of the battery-management system can be used.
With two integrated output channels that can be switched on and off by the SPI register commands, it’s possible to control a dedicated pre-charge path or separate the charging and discharging current path of the battery, reducing PCB space and overall cost. The output of the current-sense amplifier can be monitored by the MCU to implement protection such as wire overtemperature.
This new device is said to be ideal for applications such as a battery protection switch, input protection switch, and static load and supply switch for high currents.
Infineon’s 2ED4820-EM generates the supply for the gate outputs based on an integrated one-stage charge pump with external capacitors. The integrated charge pump enables external MOSFETs to stay continuously on. Thanks to the enhanced turn-on and turn-off ability of the
driver, the number of MOSFETs can be easily scaled up to manage large currents on the order of several hundred amps while ensuring a fast switch on and off.
The part also supports the back-to-back configuration, both common-source and common-drain structures. In a common-source configuration, one gate output can be used to pre-charge highly capacitive loads.
Protection and Monitoring Features
The 2ED4820-EM comes with several latching failure detections to implement protection for the external MOSFETs, the load, and the power source. Parameters can be adjusted by the SPI, monitoring data, configuration, warning, and failure detection registers.
It also offers two non-latching failure detections, monitoring the supply voltage Vbat and switching off the MOSFETs when Vbat is in undervoltage or overvoltage condition. Additional diagnostic features are provided, too, such as a warning on the internal IC temperature and monitoring the source voltage in off state to identify open load conditions before switch on.
Other built-in protection and monitoring features allow the engineer to diagnose, verify, and act against system faults:
- Supply undervoltage and overvoltage detection with configurable restart timer.
- Charge-pump undervoltage detection.
- Gate-to-source undervoltage detection with immediate lockout to prevent linear mode conduction of the MOSFETs.
- Configurable drain-to-source overvoltage detection, which also can be deactivated.
- Configurable overcurrent protection based on an analog current-sense amplifier compatible for high- or low-side shunt topologies.
- Internal overtemperature warning and protection.
An interrupt pin informs the MCU whenever one of these protections is triggered. Status registers can then be read by the MCU to understand the notification trigger. The MCU is able to monitor the output of the current-sense amplifier to implement additional protections, such as wire overtemperature.
This dual-channel high-side gate driver can tolerate negative voltages at Vbat down to −90 V and voltages up to +105 V. These different voltage conditions could be triggered by a short circuit or failure to connect the contact. In addition, the new driver comes with an amplifier that senses current to measure the low or high sides.
48-V Evaluation Board
An evaluation board and a reference board equipped with the EiceDRIVER APD 2ED4820-EM are available to speed up the design-in process. With the board, various configurations can be tested: common-source or common-drain back-to-back MOSFET structures, high- or low-side current sense, and a pre-charge path for capacitive loads up to 1 mF.
Control is performed by the µController board (XMC2GO) via the SPI. The board is operated via dedicated Windows-based user-interface software running on a PC connected over USB. The evaluation board targets typical 48-V automotive power-distribution applications and can be used with currents up to 20 A.
The AEC-Q100-qualified 2ED4820-EM is in production now. The device is Infineon PRO-SIL ISO26262-ready and comes with a safety application note to facilitate usage in functional-safety applications. Safety documentation, such as a safety manual and safety analysis summary report, can be made available for dedicated PRO-SIL products (an NDA may be required). The company’s PRO-SIL logo will guide you to products (hardware, software, safety documentation) with SIL-supporting features.