The new TB9044FNG is housed in an HTSSOP48-P-300-0.50 package measuring 6.1 mm x 12.5 mm x 1.0 mm. Safety-critical automotive systems, such as electric power steering (EPS) and brakes, are required to meet ASIL-D [2] requirements, the highest level of automotive safety integrity prescribed in the ISO 26262 functional safety standards. The new IC integrates various fault detection functions, including high and low voltage detection, power supply circuit overheat detection to monitor for IC-specific faults, and a watchdog timer to monitor fault detection by external MCUs. An initial diagnostic circuit is also incorporated to detect latent faults in the fault detection circuits, ensuring enhanced functional safety. The IC generates a 6V output from a high-efficiency buck-boost DC-DC converter. To prevent problems following a voltage drop during startup, the lower end of the operating voltage range is enhanced to 2.7 V (min.) when running on battery power. Toshiba has conducted a series of functional safety analyses to simulate system failures and will provide customers with documentation, such as the FMEDA Functional Safety [3], to support overall safety and design analysis. The IC incorporates four series power supply output circuits [4] that receive the 6 V input generated by the DC-DC converter. It also incorporates a 5 V constant voltage output circuit (400 mA current capacity) for the microcomputer, and three 5 V constant voltage output circuits (100 mA current capacity) for sensors and other interfaces. Each of these can output a specific voltage independently. Sample shipments begin today, with serial production scheduled to start in October 2017.
Grades
[1] Standards based on functional safety seek to minimize the risks resulting from system failures. ISO 26262 certification recognizes that the processes or products of an electrical and electronic (E/E) systems company for automotive applications meet the stringent criteria specified in the standard and provides third parties with an independent means of evaluating the capabilities of a potential supplier.
[2] ASIL: Automotive Safety Integrity Level
[3] FMEDA: Failure Modes Effects and Diagnostics Analysis
[4] Series power supply: The DC power supply circuit in which a voltage control element is connected to a load in series.
[5] SPI: Serial Peripheral Interface
