New Power Supply Monitoring IC with Built-In Self-Diagnostic Function that Supports Functional Safety

June 18, 2019

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

ROHM's New Power Supply Monitoring IC - VQFN16FV3030 with Wettable Flank Package

ROHM recently 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.

In 2017 ROHM developed an LCD chipset which supported functional safety and comprised of LCD drivers and power supply ICs ahead of the industry. In 2018 the company acquired certification of the development process under the international functional safety development standard ISO26262. At this time, when considering the safety and redundancy of systems, incorporating various self-test and monitoring functions ROHM created the industry’s first power supply monitoring IC with built-in self-diagnostic function that makes it easy to add functional safety to existing systems.

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. In addition to voltage monitoring functions (Power Good, reset) and a watchdog timer for monitoring the ECU essential for functional safety, ROHM’s power supply monitoring IC is the first in the industry to introduce a self-diagnostic function. 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.

BD39040MUF-C Power Supply Monitoring IC System Diagram

ROHM is committed to contributing to technological innovation in the automotive sector by developing products that achieve greater system optimization and energy savings.

Availability: Now (samples), August 2019 (OEM quantities)

Key Features

The BD39040MUF-C is the first power supply monitoring IC in the industry to include a self-diagnostic function along with additional features that make it ideal for functional safety systems required for ADAS and automated driving.

Functional Safety, Superior Versatility, High Reliability, Compact Size

1. Self-diagnostic function provides the reliability needed for functional safety
For functional safety, to clear the highest safety requirement level (ASIL) it is necessary to detect potential failures of the power supply monitoring function itself. For example, in the case a failure occurs when a monitoring function (i.e. overvoltage) cannot detect an abnormality, it becomes a hidden fault that masks the breakdown, creating a dangerous situation.
In order 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.


2. Provides flexible support for existing systems
The BD39040MUF-C easily supports functional safety in existing systems without any changes of power supply sequences. Additionally, the watchdog timer for ECU can be adjusted via 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.

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

Product Overview

  • Input Voltage Range: 2.7V to 5.5V
  • Self-diagnostic function
  • Reset function (overvoltage/undervoltage monitoring)
  • 4ch voltage monitoring function (overvoltage/undervoltage)
  • Reference voltage self-monitoring function
  • Oscillation frequency self-monitoring function
  • Window-type watchdog timer (WDT)
    (Monitoring time can be set via external resistor; effective WDT timing can be turned ON/OFF)
  • Enables air/ground fault detection of the WDT input signal using the WDOUT pin
  • AEC-Q100 (Grade 1) qualified


Functional Safety
Functional safety includes safety measures (concepts for ensuring safety) that minimize risk by adding functionality such as monitoring and protective equipment. In the automotive market, functional safety minimizes risk to an acceptable level in order to prevent bodily injury in the event of malfunction due to electronic system failure. There is an international standard for automotive functional safety (ISO26262). Meanwhile, protection functions frequently referred to in ICs are functions that ensure the safety of the IC itself by monitoring for internal malfunctions and destruction.

Functional Safety Example