L9966 datasheet(65/122 Pages) STMICROELECTRONICS

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Once VRS_A (VRS_SEL=1) or VRS_B (VRS_SEL=0) has been configured, hysteresis and filtering strategy are

defined through VRS_CONF_MODE[1:0] bit in the same VRS register:

•

VRS_CONF_MODE[1] defines filtering function (OFF/ON and if ON, its time value)

•

VRS_CONF_MODE[0] defines the hysteresis (manual or adaptive)

The next two tables summarize the parameters of VRS_A and VRS_B architecture; the two configurations are:

•

In VRS_B limited adaptive and SPI configuration, it is possible to force the default hysteresis value (HI1) by

setting MIN_HYST_FORCE bit in VRS register.

•

In VRS_A fully adaptive and SPI configuration, it is possible to force the default hysteresis value (HI3) by

setting MIN_HYST_FORCE bit in VRS register.

Entering in normal mode, in order to properly initialize the VRS block, it is recommended to have the first

VRS_OUT toggles with low HIx value – manual mode (default condition) and then configure VRS block itself.

Table 46. VRS_A hysteresis and filter time definition

VRS_SEL

(A config.)

VRS_CONF_

MODE[1:0]

Filter

Hyst

MIN_HYST_FORCE

OFF

0 µs

Manual

Ref to VRS_A – Manual Hysteresis

Active

OFF

0 µs

Full adaptive

Ref. to VRS_A – Fully Adaptive Hysteresis

Active

T(n-1)/32

Manual

Ref to VRS_A – Manual Hysteresis

Active

T(n-1)/32

Full adaptive

Ref. to VRS_A – Fully Adaptive Hysteresis

Active

Table 47. VRS_B hysteresis and filter time definition

VRS_SEL

(B config.)

VRS_CONF_

MODE[1:0]

Filter

Hyst

MIN_HYST_FORCE

OFF

0 µs

Manual

Ref. to VRS_B – Manual Hysteresis

Active

OFF

0 µs

Limited adaptive

Ref. to VRS_B –Limited Adaptive Hysteresis

Active

2.5 µs

Manual

Ref. to VRS_B – Manual Hysteresis

Active

2.5 µs

Limited adaptive

Ref. to VRS_B –Limited Adaptive Hysteresis

Active

In case a change of VRS_SEL bit within the normal operating mode occurs (1->0 or 0->1) with hysteresis current

active, this leads to the change of the hysteresis not synchronized with any VRS_OUT zero crossing.

15.2.2

VRS_A – Manual Hysteresis

To set the manual hysteresis on VRS_A configuration, bit VRS_CONF_MODE[0] has to be configured at ‘0’.

Hysteresis value is manually set through VRS_HYST_CONF[2:0] of VRS register according to Table 48. VRS_A

hysteresis value. Such hysteresis is fixed until a new SPI programming occurs.

Default hysteresis current after exiting reset is HI3.

New SPI current value is updated during HYST CURRENT OFF phase that means the output comparator is high.

The following hysteresis value ranges include also the error given by the temperature behavior of the leakage

currents on the input pins.

L9966

VRS - Normal mode

DS12459 - Rev 10

page 65/122

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