Motor pre-driver chip meets ASIL-D

April 02, 2015 // By Christoph Hammerschmidt
Meeting the highest safety level (ASIL-D) in the nomenclature of functional safety standard ISO 26262, Toshiba Electronics’ brushed motor pre-driver IC TB80507FG is suited for even the most critical applications in cars such as power steering.

The TB80507FG integrates a pre-driver, dual motor current detection circuit that converts motor current to voltage and output to MCU, It also integrates motor direction detection circuitry that detects whether external MOSFETs turn on or off normally and output the direction information to MCU.
Various failure detection circuits such as VB undervoltage detection circuit, VDD undervoltage detection circuit, over temperature detection circuit, and short circuit detection circuitry that detects any short circuit between the drain and source of a driver (MOSFET) 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 battery operation voltage range has been reduced to 5V (min.) compared to the 6V (min.) of the predecessor product.
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 new 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 9.0mm by 9.0mm by 1.6mm, the IC supports an operating voltage range of +5 to 21V and has an operating temperature range of -40°C to 125°C.
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