L9396 datasheet(44/109 Pages) STMICROELECTRONICS

44 / 109 page

Remote sensor interface

L9396

44/109

DS12539 Rev 6

Figure 8. Standstill operation diagram

Data from the sensor are not latched: last incoming frame overwrites the previous one once

validated. Faults coming from diagnostic (i.e. over current, short to ground or battery) are

latched until the microcontroller reads them.

We have two different digital algorithms:



Auto-adjusting current trip points. With this option, the IC is able to find sensor base

current value (named IB0). Range of base current can be configured via SPI. The IC is

also able to detect the current value of the data pulse and compute the first threshold

(named Ith1): Ith1 = IB0 + (ΔIth1)/2 where ΔIth1 range is also configurable via SPI.

Besides, in case of VDA selected, the IC is also able to recognize the current value of

the speed pulse by computing a second threshold (named Ith2): Ith2 = IB0 + ΔIth1 +

(ΔIth2)/2 where ΔIth2 range is configurable via SPI.



Fixed current trip points where the thresholds are set by SPI. To avoid the risk of wrong

settings (inverted thresholds, thresholds outside WSI limits and similar) only the first

threshold can be directly programmed while, to determine the second one, an offset vs.

the first threshold must be provided. Both values, threshold and offset, can be specified

through an 8-bit word (range 0x00 → 0xFF). A fixed offset of 54 (0x36) is also added to

determine the actual thresholds in order to prevent any potential wrong setting out or

range. Complete formulas for threshold computation are the following:

–

First threshold (typ.) = 93.75 µA*(54 +WSI_FIRST_TH)

–

Second threshold rising edge (typ.) =

93.75 µA*(108+WSI_FIRST_TH+WSI_OFFS_TH)

–

Second threshold falling edge (typ.) =

93.75 µA*(108+WSI_FIRST_TH+WSI_OFFS_TH)*0.6865

–

WSI_FIRST_TH: SPI programmable from 0x00 to 0xFF (default = 0x33)

–

WSI_OFFS_TH: SPI programmable from 0x00 to 0xFF (default = 0x34)

GADG1901171624PS

Sensor current

WSO pin

Bit SSDIS = 1

First not stand still

pulse is suppressed

WSO pin

Bit SSDIS = 0

Stand still time

L9396 Datasheet(PDF) 44 Page - STMicroelectronics

L9396 Datasheet(HTML) 44 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL