L9918 datasheet(10/109 Pages) STMICROELECTRONICS

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•

Current limitation enabled accordingly to current limitation thresholds provided by LIN or by NVM registers

contents (the lower between the two current limitation thresholds is adopted).

•

Safety functions active.

•

Thermal compensation enabled.

•

Low voltage function.

1.5.5

Regulation default

This mode is equivalent to the LIN regulation mode except that, being without LIN communication, NVM default

regulation parameters (VBSPDEF, TFLRCup, TFLRCdw, SPLRC) are used for regulation.

Regulation default can be entered from wake-up state when phase rotation is greater than SPSS (N_NOTSTART

NVM register). Phase amplitude required to enter regulation default depends on KLV_AC_ADAP_MIN_NOT,

KLV_AC_ADAP_MIN and ACADAPMIN_MODE NVM registers.

Regulation default can be entered from LIN regulation state in case no valid frame is provided for a time longer

than tLIN_COM, adopted set point changes from VBSPLINRG to VBSPDEF.

Set point transition to default VBSPDEF is performed with a ramp of VBSP_LDslope and excitation current

limitation moves to IFELD_MAXB or I_MAX with a ramp of IFLIM_LDslope.

If LIN communication resumes, regulation voltage and current limitation target change immediately, accordingly to

the received RX frame data.

In regulation default state:

•

LRC function enabled accordingly with NVM selection.

•

Phase regulation enabled.

•

Current limitation set to IFELD_MAXB and I_MAX.

•

Safety function enabled.

•

Thermal compensation enabled.

•

Low voltage function.

1.5.6

Safety

Safety state is an excitation OFF state which is entered as soon as a safety protection mechanism is activated

while device is into pre-excitation or regulation state.

Here below a list of the safety mechanisms implemented by L9918:

1.5.6.1

Current protection

In all the states where the excitation power MOS is active, overcurrent protection function is working. As soon as

the IFOCP threshold is reached the power is switched OFF.

1.5.6.2

Thermal protection

In case TJ reaches the Tsd,x threshold (selectable by NVM bits THERMAL_TH_SEL), EXC power MOS is

switched OFF till the TJ temperature decrease below Tsd,x - Tsdhy.

1.5.6.3

Overvoltage safety protection

In case of B+ > VBOV_safetyL for more than TOVflt_safetyL or B+ > VBOV_safetyH for more than TOVflt_safetyH, EXC

power MOS is switched OFF till B+ returns at a value lower than VBOV_safetyL for more than TOVflt_safetyL time.

L9918

State diagram

DS13000 - Rev 2

page 10/109

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