TLE4942, TLE4942C
I
Xn
IHigh
Xn+1
Xn+2
ILow
t
1
T
duty = t1 / T * 100%
t
Figure 7 Definition of duty cycle
PWM Current Interface
Between each magnetic transition and the rising edge of the corresponding output
pulse the output current is Low for tpre-low in order to allow reliable internal
conveyance. Following the signal pulse (current is High) is output.
If the magnetic differential field exceeds ∆BEL, the output pulse lengths are 90µs or
180µs respectively, depending on the direction of rotation.
When the magnitude of the magnetic differential field is below ∆BEL, the output pulse
lengths are 360µs and 720µs respectively, depending on left or right rotation. Due to
decreasing cycle times at higher frequencies, these longer pulses are only output up
to frequencies of approximately 117Hz. For higher frequencies and differential
magnetic fields below ∆BEL, the output pulse lengths are 90µs or 180µs respectively.
If the magnitude of the magnetic differential field is below ∆BWarning, the output pulse
length is 45µs. The warning output is dominant, this means that close to the limit
airgap the direction and the assembly position information are disabled.
For magnitudes of the magnetic differential field below ∆BLimit, signal is lost.
In case no magnetic differential signal is detected for a time longer than the stand still
period Tstop, the stop pulse is output. Typically with the first output stop pulse, the
circuitry reverts to the uncalibrated mode.
TLE4942 - TLE4942C Data Sheet
12
February 2002