SLVSE17A May 2019 – April 2020 TPS1HB16-Q1
The TPS1HB16-Q1 device contains two types of voltage clamps which protect the FET against system-level voltage transients. The two different clamps are shown in Figure 33.
The clamp from VBB to GND is primarily used to protect the controller from positive transients on the supply line (for example, ISO7637-2). The clamp from VBB to VOUT is primarily used to limit the voltage across the FET when switching off an inductive load. If the voltage potential from VBB to GND exceeds the VBB clamp level, the clamp will allow current to flow through the device from VBB to GND (Path 2). If the voltage potential from VBB to VOUT exceeds the clamping voltage, the power FET will allow current to flow from VBB to VOUT (Path 3). Additional capacitance from VBB to GND can increase the reliability of the system during ISO 7637 pulse 2 A testing.