Data Sheet

8

Version1.0

2016-06-15

TLE4955C

Confidential

Operating Modes and States

2.3

Direction Detection

be calculated in the direction input amplifier. This signal is digitized by an analog to digital converter

(direction ADC) and fed into the digital core.

Depending upon the rotation direction of the target wheel, the signal of the center probe anticipates or lags

behind for 90°. This phase relationship is evaluated and converted into rotation direction information by

sampling the signal of the center probe in the proximity of the zero crossing of the “speed” bridge signal.

The first pulse after power on is a speed pulse, as there is no valid direction information available.

2.4

Vibration Suppression

The magnetic signal amplitude and the direction information are used for detection of parasitic magnetic

signals. Unwanted magnetic signal can be caused by angular or air gap vibrations. If an input signal is

identified as a vibration the output pulse will be suppressed.

TLE4955C offers two different kinds of vibration suppression:

• Vibration suppression via hysteresis. This is available after power on

• Vibration suppression via direction detection. This is available after start up calibration is performed.

2.5

Undervoltage Behavior

At the first switching events after power on the undervoltage detection is activated.

If the supply voltage drops below the values specified in operating range, an active output (defined state) will

voltage reaches again the functional level.

Figure 6

Undervoltage Behavior

If the supply voltage is below 2.3 V typical the sensor will reset and initiate a new calibration.

on IC leads

VDD

on IC

leads

current

1st switching enables

VDD reset

VDD voltage drops due to

due to undervoltage

The sensor starts with

power on process

Startup

Mode

Operating Mode

Undervoltage

Operating Mode

Release

pre -low bit