L9788 datasheet(141/264 Pages) STMICROELECTRONICS

141 / 264 page

DS12308 Rev 4

141/264

L9788

Inductive sensor interface

263

Figure 59. EN_FALLING_FILT = 1

Figure 60. EN_FALLING_FILT = 0

11.2.5

VRS_B - Manual Hysteresis

To set the manual hysteresis on VRS_B configuration, bit VRS_MODE [0] has to be set to

'0'. Hysteresis value is manually set through VRS_HYST [2:0] of CONFIG-REG 8 according

to Table 58 Such hysteresis is fixed until a new SPI programming occurs.

Once a new value is defined, new hysteresis threshold is applied after the second VRS_FB

H-L transition and until the next rising edge of the VRS input differential voltage occurs.

11.2.6

VRS_B -Limited Adaptive Hysteresis

To set the limited adaptive hysteresis on VRS_B configuration, bit VRS_MODE [0] has to be

set to '1'. In this mode, user programs a hysteresis threshold through VRS_HYST [2:0] bit in

VRS register and the internal logic selects a hysteresis based on input signal peak value:

the maximum of these two values is actually applied.

Once a new value is defined, new hysteresis threshold is applied after the second VRS_FB

H-L transition and until the next rising edge of the VRS input differential voltage occurs.

11.2.7

VRS_B - Fixed Filter Time

In VRS_B configuration, it is possible to enable the filter time on the output of the zero

crossing comparator through the bit VRS_MODE[1] of VRS register. This configuration

allows defining the internal filter time at a fixed value of 4 µs, active on both rising and falling

edges of VRS output.

GADG0612161235PS

Vdiff

VRScomp_filt

FILTER TIME

GADG0612161240PS

Vdiff

VRScomp_filt

MASK TIME

L9788 Datasheet(PDF) 141 Page - STMicroelectronics