A robust smart power bandgap reference circuit for use in an automotive environment

In the development of smart power products for automotive applications, robustness to all kinds of disturbances is one of the key issues. For junction-isolated smart power technologies such as SPT¹, negative voltages at the drain terminal of a power DMOS lead to minority carrier injection into the substrate. This can cause malfunction of sensitive circuits such as bandgap references and may subsequently lead to severe functional failures of the device. Furthermore, in smart power ICs very high chip temperatures can occur due to excessive power dissipation on- or off-chip in fault conditions. In such cases, the operation of a bandgap reference must be guaranteed to ensure safe shutdown of the device even at excessive chip temperatures. A robust bandgap circuit for the use in smart power ICs is presented which is insensitive to minority carrier injection into the substrate and operates reliably up to 260°C.