General-Purpose Automotive MCU System Power Supplies for Idling Stop Systems - Advanced design ensures optimum MCU performance even during cranking -

ROHM has recently announced the development of system power supplies optimized for high-performance microcontrollers in a variety of automotive systems, from electronic power steering to fuel injection, including HEVs and EVs.

The newly developed BD39001EKV-C utilizes a proprietary boost-buck switching method that ensures stable voltage supply, even when the battery voltage drops after idling stop, while improving power conversion efficiency by up to 5% vs. conventional products. And in response to the continued standardization and advancements in the automotive industry a startup sequence setting function is included that can adapt to a variety of MCU specifications and requirements.

With the continuing trend towards platform unification (standardization) in the automotive sector comes a push to promote the use of common parts worldwide. This is expected to increase demand for versatile products that can suit a variety of requirements and support microcontrollers of all types – as well as high-performance devices and solutions optimized for customized dedicated power supplies and specific applications.

In addition, the need to minimize fuel consumption has led to the adoption of idling stop systems that stop the engine during idling and other brief stops in order to prevent wasteful fuel consumption. However, this requires countermeasures to prevent MCU malfunction due to battery voltage fluctuations caused by cranking after the engine starts up again.

In response, ROHM quickly developed a versatile, standardized power supply IC capable of providing stable voltage after idling stop operation. The BD39001EKV-C utilizes leading-edge 0.35um BiCDMOS power processes and takes advantage of ROHM’s analog design expertise to achieve a breakdown voltage of 40V with an ultra-low drive voltage of 4V, providing a wide input voltage range.

And to ensure compatibility with idling stop systems, ROHM adopted a new boost-buck automatic switching control method that provides stable voltage (5V) to the MCU, even when the battery voltage fluctuates (below 5V), while increasing power conversion efficiency by 5%.
Besides providing continuous, stable power supply for I/O (5V LDO) and the MCU core (3.3V DC/DC) based on a variable primary power supply, a number of surveillance functions are built in, including a window watchdog timer that monitors MCU operation, improving reliability. The products also feature a compact form factor that contributes to end-product miniaturization.

Pricing: $5 / unit (Excluding Tax)
Availability: Now (Samples), Dec. 2014 (OEM Quantities)

ROHM is actively expanding its lineup of versatile, standardized energy- and space-saving high reliability power supply ICs for the automotive market.

Key Features

1. New boost-buck automatic switching control ensures stable operation even during cranking and increases energy savings by up to 5% over conventional products
The unique design automatically switches between boost and buck circuits to provide continuous voltage to the MCU without worrying about battery voltage drops (below 5V) when the engine starts after idling stop operation.

At the same time, power conversion efficiency during cranking is improved by 5% (conditions: Vin=4V, Vout=5V, Iout=2A, Fosc=350kHz), making it ideal for vehicles
equipped with idling stop systems.

2. Startup sequence setting function compatible with virtually any MCU
The startup sequence can be freely set by connecting a capacitor to the EN terminal, enabling support for a variety of microcontrollers and contributing to the common use of peripheral products and platforms.

3. Window watchdog timer function improves reliability
Watchdog timers monitor the MCU signal and conduct reset and restart operations under initial conditions when abnormalities are detected. The BD39001EKV-C integrates a high-performance window watchdog timer that not only monitors the MCU signal, but also detects frequency variations, contributing to greater reliability.

Product Lineup

Applications

◇HEV / EV Inverters ◇Fuel Injection (FI)
◇Electronic Power Steering (EPS) 

◇ADAS (Advanced Driver Assist Systems) And other devices and systems utilizing high-performance 16bit/32bit MCUs

Terminology

LDOs and DC/DC Converters
DC/DC converters are normally preferred over LDOs when driving more sophisticated, high-performance microcontrollers (i.e. higher powered 16bit/32bit MCUs) in automotive applications.