1 Introduction

Automotive loads include a wide range of resistive, capacitive and inductive loads across a wide power band. From incandescent headlights to traction inverters to on-board chargers, the unifying requirement is AEC-Q100 compliance for devices that drive these loads. A major push in the automotive industry is to increase the number of driver assistance systems that provide additional information to the user about the status of the vehicle. Such systems take advantage of more than one methods of feedback to the user like touch, sound and sight to provide quick feedback and therefore can be used to improve safety and handling of the automobile. These loads are commonly referred to as ADAS loads or Advanced Driver Assistance Systems loads. A vital piece of a circuit is the switch used to drive the load. The switch can be placed either on the high side of the circuit, (for example, between the source and the load) or on the low side (for example, between the load and ground) of the circuit. A high side switch is usually preferred because it does not leave the load energized in the off state. This is vital since a common use case failure mode is an unintentional short to GND and if the short happens before the low side switch, then the switch cannot protect against this event. The high side switch is therefore placed closer to the power supply and the downstream loads are often further away from the control unit or switch board. A critical function of the switch is to protect the load and the source from one another.

TI high side switches integrate a NMOS based power FET along with various protection features to support switching off-board loads. TI’s high side switch portfolio includes devices with on resistances as high as 1 Ohm and as low as 8 mOhm. This choice of devices allows the user to select the right device depending on the protection features required and on the power requirements of the load. TPS1HC100-Q1 is a 100mOhm high side switch built for 12 V nominal systems that integrates protection features like a user set current limit and a high accuracy current sense output in one device. The current sensing allows for the user to have instant feedback on the condition of the device and the power flowing into the load without the need of higher power rated sensors or amplifiers. Current limiting allows for the user to drive loads that are susceptible to high current events by clamping them to the user set value. This works in hand with the integrated thermal protection of the device to automatically turn off the power path if required (for example, long fault event). The switch also has the ability to protect the load against surge events like load dump up to 35 V. TPS1HC100-Q1 also integrates a system that tracks the MCU voltage using the input to the DIAG EN pin so as to not output a voltage higher (such as during a fault event) than what the MCU or controller can safely handle. For more information on TPS1HC100-Q1, please view the data sheet here. For more information on high accuracy current sensing and high accuracy current limit of high side switches, please view their respective applications notes.