Features
• Digital Self-supervising Watchdog with Hysteresis
• One 150-mA Output Driver for Relay
• One High-side Driver for N-channel Power FET
• Positive and Negative Enable Output
• Positive and Negative Reset Output
• Over/Under-voltage Detection
• Relay and Power FET Outputs Protected Against Standard Transients
and 55-V Load Dump
1. Description
The function of microcontrollers in safety-critical applications (e.g., anti-lock systems)
needs to be monitored permanently. Usually, this task is accomplished by an indepen-
dent watchdog timer. The monolithic IC U6813B, designed in bipolar technology and
qualified according to the needs of the automotive industry, includes such a watchdog
timer and provides additional features for added value. With the help of integrated
driver stages, it is easy to control safety-related functions of a relay and of an N-chan-
nel power MOSFET in high-side applications. In case of a microcontroller malfunction
or supply-voltage anomalies, the U6813B provides positive and negative reset and
enable output signals. This flexibility guarantees a broad range of applications. The
U6813B is based on of Atmel’s fail-safe ICs U6808B and U6809B.
Fail-safe IC with
High-side and
Relay Driver
U6813B
Rev. 4543B–AUTO–10/05