The increasing importance of ISO 26262, the international standard for “Road Vehicles – Functional Safety”, requires monitoring of the functions of power supply ICs. The TB9042FTG incorporates multiple monitoring functions that detect any malfunctions of the IC and external microcontrollers. It also integrates a transmitting function that transfers data on monitoring status to an external microcontroller, which further supports improved safety.
Increasingly higher current is required for automotive applications. The efficient DC-DC converters integrated into these new ICs educe power consumption, and its series regulators realize low noise power supplies.
The chips contain two channels of DC/DC converters. One converter steps down the power supply from the vehicle battery to 6V; the other one steps this voltage level down to 1.2V or 1.5V (selectable) for the microcontroller core.
Two built-in series regulators convert the 6V supply from the DC-DC converter and independently provide constant 5V supplies: 400mA current capacity is used for the microcontroller, and 100mA current capacity is used for a sensor or other interface. A further series regulator takes power from the battery and supplies 5V or 3.3V power (selectable), which is used as back-up power supply to protect the microcontroller's RAM data.
The product incorporates abnormality detection for each output and transmits the detected data from either the SPI terminal or a special terminal dedicated to abnormality signals. An integrated diagnostic function monitors for IC malfunction by comparing its data and signals from a microcontroller, helping to realize automotive functional safety. This combination of functional building blocks enables designers to implement a variety of safety-related monitoring functions within vehicles.
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