Voltage monitoring is among the most important methods for ensuring high reliability in automotive applications. With the MAX20479, Analog Devices provides an ASIL-B-compliant voltage watchdog that monitors up to three independent voltages simultaneously.

Power supply-induced glitches and similar effects are among the most interesting issues in power electronics. A voltage-level supervisor helps address this issue by continuously monitoring the system's input voltages. If an abnormal condition is detected, a signal is asserted. It can then be used to halt further program execution until the voltage has stabilized again.

From a technical point of view, the component presents itself as shown in the figure below. When OTP programming is provided, the three inputs are continuously monitored. If an invalid voltage level is detected on one of them, the reset outputs can be asserted to trigger watchdogs or similar reset procedures. This can, for example, be useful for monitoring FPGAs. These are known to react especially interestingly when faced with power supply interruptions.

High-Accuracy Voltage Monitoring

For voltage level determination, Analog Devices specifies the following. Designers can deploy the component without worrying about regulation thresholds or accuracy:

Inputs 1 and 2 can be configured to monitor a voltage between 0.5V and 3.6875V in 12.5mV steps, while input 3 can be configured to monitor a voltage between 0.5V to 5.6V in 20mV steps. Each input has programmable OV/UV thresholds of between 2.5% and 10% with ±0.8% accuracy.

Multiple SKUs Offer Different Input Complements

As of this writing, Maxim Integrated / Analog Devices provides a total of four different voltage monitors. All are qualified to AEC-Q100 and can withstand an extended temperature range of -40°C to +125°C, which is commonly found in automotive applications.

SKUs MAX20479A and MAX20479C, then, provide a two-channel version of the voltage monitor. Ordering SKUs MAX20479B or MAX20479D, instead, provides the three-channel version.

Evaluation Boards Available

Designers working on an automotive voltage monitor design can use the MAX20479EVKIT evaluation board. It is a turnkey kit that can be used to directly evaluate the behavior of the voltage regulator. This way, software development can proceed in parallel with PCB design.

Conclusion

Ensuring voltage stability in automotive designs greatly increases system reliability. With the MAX20479 family, Analog Devices provides a component that is ready to help. Its low total cost of ownership and very compact housing mean the component can be comfortably integrated into even the smallest designs. In short, a chip that is always deserving of the highest recommendation.