Providing enhanced functional safety and control for automotive applications such as electric power steering systems, a brushed motor pre-driver IC has been introduced by Toshiba Electronics Europe. The IC meets the requirements set in Automotive Safety Integrity Level D (ASIL-D), the most stringent automotive safety integrity levels prescribed by ISO 26262, Road Vehicles – Functional Safety.
The TB9057FG integrates a pre-driver circuit, a dual motor current detection circuit which converts motor current to voltage and output to MCU and motor direction detection circuitry that detects whether external MOSFETs turn on or off normally and output the direction information to the MCU.
Various failure detection circuits such as VB under voltage detection circuit, VDD under voltage detection circuit, over temperature detection circuit and short circuit detection circuitry are also integrated into the IC. Additionally, functions including motor current detection circuit, power supply PIN and GND PIN are made redundant to secure higher robustness.
In order to accommodate the possibility of a voltage drop caused by cranking after idling reduction, the minimum battery operation voltage range has been reduced to 5V, compared to the 6V of the predecessor. The built-in motor current detection circuit and motor direction detection circuit simplifies system design and reduces PCB size.
Customers can set the system to respond to detected failures, in one of two ways, using the input setting of the SEL pin. One setting uses this IC to stop the external MOSFET, the other switches to external control of the MOSFET using the MCU. Selection can be made according to the customer’s application or system and reduces loads on the MCU. Toshiba has also carried out a range of functional safety analyses to simulate various system failures and will provide customers with documentation to support safety analysis and design.
Housed in a LQFP48-P-0707-0.50C package measuring 9.0x9.0x1.6mm, the IC supports an operating voltage range of 5-21V and has an operating temperature range from -40 to +125°C.