IPDs replace relays in automotive power controls

March 15, 2016 // By Graham Prophet
A series of intelligent power devices (IPDs) with low on-resistance is intended as a replacement for relays in automotive applications; they are optimised for applications such as motor and heater controls

The set of six intelligent power devices provide a reliable, high-performance solution, integrating control circuits that implement protection and self-diagnostic functions, in addition to power MOSFET switches. Renesas notes that the transition from mechanical relays to semiconductor switching began in applications such as lighting control, and the trend is expanding to other automotive systems, such as motor and heater control, driving demand for highly reliable and high-performance semiconductor switching devices.


The IPDs combine Renesas’ low-loss technology and a new fabrication process with a cell size of 2 µm to achieve an on-resistance of 1.6 mΩ (RAJ280002, typical value when Tch = 25°C). This also enables adoption in high current applications, and it further allows the new devices to replace conventional mechanical relays and provides a reduced mounting area, contributing to smaller and more lightweight ECUs. As solid state devices, the IPDs deliver extremely high reliability and performance levels, operating at up to 100 million switching cycles with no degradation.


Guaranteed on-resistance characteristics at low power supply voltages and built-in diagnostic functions: an earlier Renesas device, the µPD166033, would transition to the off state when the power supply voltage dropped to 4.5V as a protection function to prevent malfunctions. These IPDs incorporate enhancements that provide support for continued operation when the voltage obtained from the battery drops temporarily, such as during starter motor cranking. The guaranteed on-resistance characteristics at a power supply voltage of 3.2V allow the IPDs to be used in applications where starter motor cranking might otherwise be an issue. The IPDs also feature built-in diagnostic functions and proportional load sensing. This allows for clearly defined fault signals that flag the system/controller when an abnormal load condition is detected. Since the analogue current sense feedback is available, no additional load current sense elements are required.


Tolerance of EMF spikes from inductive loads – for example, in the RAJ280002 – increases from the 260 millijoule (mJ) of