L9965T datasheet(13/62 Pages) STMICROELECTRONICS

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State

Purpose

Reached

from

Condition

Active

resources

CYCLIC_WAKEUP

To perform

cyclic

diagnostics

during low

power

operation

CYCLIC_

COUNT

CYCLIC_WAKEUP timer expired (in sender mode)

Wake up Via VIF

Cyclic wakeup

diagnostic

routine

NORMAL

Full operation

DEEP

SLEEP

•

FAULT/WAKEUP tone received from VIF

•

CYCLIC_WAKEUP tone received from VIF

•

WAKEUP command received from SPI

All resources

fully operative

CYCLIC_

COUNT

•

FAULT/WAKEUP tone received from VIF

•

WAKEUP command received from SPI

•

CYCLIC_WAKEUP timeout expired (in listener

mode)

CYCLIC_

WAKEUP

•

Internal fault detected during diagnostic routine

•

FAULT/WAKEUP tone received from VIF

•

WAKEUP command received from SPI

For the special frames VIF FAULT/WAKEUP tone, VIF CYCLIC_WAKEUP tone and SPI WAKEUP sequence,

refer to Section 5.8.3.

5.1.1

NORMAL State and wakeup sources

In NORMAL mode all resources are fully available.

5.1.1.1

Wakeup Sources

The L9965T/TS responds to three wakeup sources:

•

Wakeup via VIF

–

The IC is daisy-chained on the VIF bus along with other companion chips, and can be woken up by

VIF special frames (CYCLIC WAKEUP or FAULT/WAKEUP frames) sent from another device (see

Section 5.8.3)

•

Wakeup via SPI

–

The IC can be woken up by any dummy frame received on the SPI

•

Self-Wakeup

–

A wakeup trigger is internally generated when the device is in CYCLIC_WAKEUP mode (see

Section 5.1.2).

The device can reach NORMAL state from low power states by the wakeup via SPI and via VIF sources,

described below.

Whenever a wakeup source is validated, the wakeup sequence is initiated and shall successfully end within

TWAKEUP_TIMEOUT. Otherwise, the IC returns to DEEPSLEEP state

5.1.1.1.1

Wakeup via VIF

When in DEEPSLEEP, CYCLIC_WAKEUP or CYCLIC_COUNT the IC is sensitive to wakeup signals incoming on

VIF port (see Section 5.8.3).

Figure 6 shows a typical application scenario where some L9965x in the chain has self-detected a fault and

wakes up the daisy-chain sending the FAULT/WAKEUP tone on both VIF ports.

The wakeup by fault of a VIF daisy chain device is an asynchronous event with respect to the CYCLIC_WAKEUP

thread managed in background by the L9965T/TS. Fault notification mechanism guarantees that the FAULT/

WAKEUP tone is correctly propagated at least in one direction, even in case of conflict with the

CYCLIC_WAKEUP tone.

Depending on the position of the sending L9965x in the daisy chain, the wakeup interrupt reaches the MCU in

approximately less than:

½*NVIF_STACK*TVIF_WAKEUP_TIME ≤ t ≤ NVIF_STACK*TVIF_WAKEUP_TIME.

L9965T/L9965TS

Functional description

DS14987 - Rev 1

page 13/62

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