L9918 datasheet(8/109 Pages) STMICROELECTRONICS

8 / 109 page

Figure 4. L9918 finite state machine diagram

Self start (N>SP

)

OR hot start

(N<Nstart)

FAULT

OFF

VBSPLINRG

LIN COM TO

Regulation State

Regulation

Default

LIN

Regulation

(*) Considered timeout depends on the wakeup

sources. If no LIN activity is detected (device

wakeup by phase) device consider PH TO. If LIN

activity is detected, adopted timeout is LIN TO,

independently of the wakeup event.

(**) In case REG_AUS = 0x1, EXC is disabled

when VBSPLINRG = 10.6.

Standby

Pre-Excitation

(LIN TO) OR

(PH TO) OR

LIN Sleep Command

LIN Activity

PH Activity

VBSPLINRG ≠ 10.6

FAULT OFF

FAULT ON

Wake Up

Safety

(EXC OFF)

LIN COM TO

VBSPLINRG = 10.6

ss,x

(N>Nstart)

(N<Nstart)

N<Nstart

(**)

(*)

1.5.1

Standby

Device conditions to enter in stand-by mode:

•

LIN time-out or phase time-out;

•

LIN sleep command.

Device considers two different timeouts to go back to standby from wake up: LIN timeout and phase timeout.

LIN timeout means: no activity on LIN bus during specified time (see tLIN_to parameter).

Phase timeout means: no activity on phase signal during a specified time (see tPH_to parameter).

Standby entrance from Wake Up state can be done accordingly to one of the two timeouts. In case no LIN activity

is detected (wake up by phase), device goes in standby if no more PH activity occurs for longer than tPH_to.

If LIN activity is detected, device transition from Wake Up to Standby uses tLIN_to independently of the wake up

source.

The standby mode can even be forced by ECU sending LIN sleep command.

In stand-by state the device has:

•

No excitation. Duty cycle (DC) on EXC pin is equal to zero.

•

Current consumption aligned to IBstbyL80, IBstbyH80, according to the internal temperature.

In this state the device needs a small amount of quiescent current to supply logic, phase detector and LIN

receiver only.

When device is supplied after a shutdown, as soon as the voltage reaches VBPOR threshold, the digital block in

charge of evaluate input coming from PH and LIN pins is initialized. For this reason only B+ levels higher than

VBPOR can ensure device wakeup functionalities.

1.5.2

Wake-up

This state is reached from Standby if at least one of the following wake up sources occur:

•

Activity is detected on LIN bus (LIN wakeup event selected by LIN_WAKEUP_PATTERN NVM bits,

accordingly to LIN specification document).

•

Activity on PH pin is detected (VPStartTh).

Wake up state can also be accessed from Pre-excitation state in case no valid communication is provided for

more than LIN COM timeout (tLIN_COM) or in case VBSPLINRG = 10.6 is received.

L9918

State diagram

DS13000 - Rev 2

page 8/109

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