L9918 datasheet(27/109 Pages) STMICROELECTRONICS

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4.2

EXC characteristics

4.2.1

Minimum and maximum excitation duty cycle:

It is possible to set minimum and maximum excitation duty cycle by NVM bits PWM_MINEIN and PWM_MINAUS.

Such limits are valid just if the DC calculated by regulation loop is different from 0 % and from 100 %.

4.2.2

Load response control

As previously mentioned, LRC consists in applying a given DC change rate instead of applying the DC calculated

by the regulation loop.

Shape of the DC change rate is reported in the picture below:

Figure 11. Load response control

DC[%]

(TV_SPRUNG)

LRC rise time

(LRD_DEF or LIN)

LR_TVFILTER_PER

(ΔT multiple of EXC PWM period)

LRC rise time can be set by LIN or by LRD_DEF NVM bits. It is defined as the transient time needed to pass from

DC = 0 % condition to DC = 100 % condition.

LRC function is disabled if PH rotation is higher than LRC cut-off threshold. Such threshold can be selected by

LIN or by NVM bits LRDN_DEF. Default value selected by NVM programming is ignored in case a valid cut-off

frequency is provided through LIN communication.

Other LRC options selectable by NVM bits are: LR_TVFILT_SEL, LR_TVFILTTIME, LR_TVFILTER_PER. Further

details on these parameters can be found in table reported into appendix A1.

LRC operation is terminated as soon as DC given by LRC slope becomes higher that the DC calculated by the

regulation loop. When this condition occurs, DC calculated by regulation loop is adopted.

Blind Zone control:

Blind Zone control by LIN communication can be enabled by NVM bit TV_SPRUNG_EN. If TV_SPRUNG_EN = 0,

device blind zone correspond to the programmed default value DFLRCBZ value.

In case TV_SPRUNG_EN = 1, blind zone can be selected by LIN RX frame. RX frame field available for blind

zone control depend on the specific LIN configuration adopted.

4.2.3

Pre-excitation specific mode selection

Short description of NVM settings related to Pre-excitation state has been provided in Section 1.5.3 Pre-

excitation.

In this paragraph is reported a more detailed description of the device behavior when Pre-excitation specific mode

is selected (SV_FORD_EN = 1). When this setting is adopted, the device has different behaviors depending on

set-point voltage sent via LIN communication.

L9918

EXC characteristics

DS13000 - Rev 2

page 27/109

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