L6364 datasheet(11/60 Pages) STMICROELECTRONICS

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Startup

At startup, power is applied via the cable on VPLUS. The embedded Power-On-Reset (POR) circuit ensures the

proper startup of the L6364 with the output switches initially in a high impedance state. The device core of the

L6364, including the control for the 5 V regulator, is supplied by the V3V3 supply.

The SPI communication logic is reset whenever SS='1' and is independent of the L6364 power on reset itself.

It is therefore possible to read the SPI register values even when the L6364 is in reset. In particular, the

STATUS:RST bit is read as part of the STATUS byte on every SPI access.

This bit is cleared when the device is in reset, or when the device has been reset. This status information can be

used as set out in Table 15 to determine the L6364 reset state, and also to react to unexpected reset conditions.

Table 15. L6364 Reset conditions

Device state

STATUS:RST

INT

Comment

Power-On-Reset (POR)

L6364 is in power on reset (checked at the start of the SPI

access). Only the STATUS:RST bit is valid. The microcontroller

may wait for a high level on INT before proceeding.

Device reset (post POR)

L6364 has been reset, and the INT line is forced high. Write

STATUS:RST='1' to allow normal operation of the L6364.

Operation

Normal operation

The microcontroller should initialize the state of the internal registers to the desired values after reset.

L6364

Startup

DS13363 - Rev 4

page 11/60

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