L9678P datasheet(35/203 Pages) STMICROELECTRONICS

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L9678P, L9678P-S

Start-up power control

202

An active low pin output (RESET pin) is driven from the L9678P to allow resetting of external

devices such as the microcontroller, sensors, and other ICs within the ECU.

Three internal reset signals are generated by the device:



POR

Power On Reset - This reset is asserted when a failure is detected in the internal

supplies or bandgap circuits. When active, all other resets are asserted.



WSM_RESET

Watchdog State Machine Reset - This reset is generated when the POR is active.



SSM_RESET

System State Machine Reset - This reset is asserted when the POR or the

WSM_RESET are active, or when a failure is detected in either Watchdog state

machine.

The RESET pin is the active-low signal driven on the output pin, and is an inverted form of

SSM_RESET. The cause of a RESET activation is latched and reported into the Fault Status

The reset logic shall be controlled as shown in the diagram below:

Figure 19. Reset control diagram

GND_ERR is a general fault signal with the purpose of driving the device into POR when

either GNDA or GNDD is shifted more than 300 mV nominal with respect to the reference

ground pins GNDSUB.

L9678P Datasheet(PDF) 35 Page - STMicroelectronics