In many automotive ECUs, the high-side switch is
need to provide diagnostic information about the downstream load current. With more
complex loads, high accuracy sensing is required. A few examples follow:
- LED lighting: In many architectures, the
body control module (BCM) must be compatible with both incandescent bulbs and
also LED modules. The inacndescent lamp load may be relatively simple to
diagnose. However, the LED module will consume less current and also can include
multiple LED strings in parallel. The same BCM is used in both cases, so the
high-side switch can accurately diagnose both load types.
- Solenoid protection: Often solenoids are precisely controlled by low-side switches. However, in a fault event, the low-side switch cannot disconnect the solenoid from the power supply. A high-side switch can be used to continuously monitor several solenoids. If the system current becomes higher than expected, the high-side switch can disable the module.