New Power Supply Monitoring IC With Built-In Self-Diagnostic Function


Facilitates the configuration of functional safety systems required for ADAS and automated driving

ROHM Semiconductors has announced the availability of a power supply monitoring IC, the BD39040MUF-C, with BIST (Built-In Self Test) that supports functional safety. This IC is ideal for automotive application power supply systems requiring fail-safe measures such as electric power steering as well as sensors and cameras for autonomous driving and ADAS.

Rapid advancements in ADAS and automated driving in the automotive sector have spurred demand for functions such as collision prevention and lane assist that reduce the risk of accidents. Accordingly, product development for mounted semiconductors has to take into account how to ensure functional safety (fail-safe) in the event of failure considering self-diagnostic and other functions.


The BD39040MUF-C is a power monitoring IC that provides monitoring functions required for functional safety in the power supply systems of ADAS sensor modules. By utilizing original technology, this IC makes it possible to detect potential failure of the power supply IC itself without affecting existing systems. The integration of these functions into a compact 3mm square package makes it ideal for ADAS applications demanding high miniaturization.

Fig 1. BD39040MUF-C Power Supply Monitoring IC System

Key Features

1. Self-diagnostic function brings the needed reliability for functional safety

In order to clear the highest safety requirement level (ASIL), it is necessary to detect potential failures of the power supply monitoring function. For example, in the case of a failure occuring when a monitoring function (i.e. overvoltage) cannot detect an abnormality, it becomes a hidden fault that hides the breakdown, creating a dangerous situation.

To overcome this, the BD39040MUF-C with self-diagnostic function utilizes original circuit technology that enables it to detect potential failures beforehand. Both the reference voltage and oscillator circuits are multiplexed to enable continuous mutual monitoring between systems in order to improve safety during normal operation.

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2. Flexible support for the existing systems

The BD39040MUF-C supports functional safety in existing systems without any changes to power supply sequences. Additionally, the watchdog timer for ECU can be adjusted via an external resistance and the effective monitoring timing arbitrarily set ON/OFF. Furthermore, the IC is offered in a compact 3mm square package ideal for ADAS applications requiring smaller form factor. This addresses the need for more compact safe driving support modules in ADAS and automated driving systems that demand functional safety.

3. Integrates various monitoring functions required by automotive power supplies and ECUs

The BD39040MUF-C incorporates a range of monitoring functions, including overvoltage and undervoltage monitoring (Power Good) required for power supplies, and watchdog timer and reset functions demanded by ECUs. Among these, the watchdog timer is a window-type that monitors whether the ECU is stuck in a loop within a programmable timeout period.

Fig 2. Features for ADAS & automated driving

Other Key Features

  • Input Voltage Range: 2.7V to 5.5V
  • 4ch voltage monitoring function (overvoltage/undervoltage)
  • Reference voltage self-monitoring function
  • Oscillation frequency self-monitoring function
  • Air/ground fault detection of the WDT (Window-type Watchdog Timer) input signal enabled using the WDOUT pin
  • AEC-Q100 (Grade 1) qualified

Application Examples

  • Radars, cameras, and sensors for ADAS/automated driving
  • ECUs
  • Electric power steering
  • Dashboard cluster, LCD panels
  • Infotainment
  • Lamps

And other power systems requiring functional safety measures beyond ASIL-B

Fig 3. Functional Safety


Samples are available now with production of OEM quantities to begin from August 2019 .

Visit BD39040MUF-C for further technical details



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