AS5040_09 Datasheet, PDF (14/34 Pages) ams AG – 10Bit 360 Programmable Magnetic Rotary Encoder

AS5040
Data Sheet
Figure 8: Incremental Output Modes
Quad A/B-Mode
A
M e ch anical
Zero Position
Rotation Direction
Change
M e c h an ic al
Zero Position
B
Index
lid Step / Dir-Mode
LSB
va ^Dir
Index=0
1LSB
Index=1
3 LSB
Clockwise cw
Hyst =
2 LSB
Counterclockwise ccw
ill ^CSn
t _{t Incremental outputs valid}
t _{Dir valid}
AG ^{t s} _{Incremental Power-up Lock Option}
s ^{n After power-up, the incremental outputs can optionally be locked or unlocked, depending on the status of the CSn pin:}
CSn = low at power-up:
e _{CSn has an internal pull-up resistor and must be externally pulled low (Rext ≤ 5kΩ). If Csn is low at power-up,}
m ^{t the incremental outputs (A, B, Index) will be high until the internal offset compensation is finished.}
This unique state (A=B=Index = high) may be used as an indicator for the external controller to shorten the
a ^{n waiting time at power-up. Instead of waiting for the specified maximum power up-time (0), the controller can}
start requesting data from the AS5040 as soon as the state (A=B=Index = high) is cleared.
o _{CSn = high or open at power-up:}
c _{In this mode, the incremental outputs (A, B, Index) will remain at logic high state, until CSn goes low or a low}
pulse is applied at CSn. This mode allows intentional disabling of the incremental outputs until for example the
l _{system microcontroller is ready to receive data.}
ica ^{Incremental Output Hysteresis}
To avoid flickering incremental outputs at a stationary magnet position, a hysteresis is introduced.
n _{In case of a rotational direction change, the incremental outputs have a hysteresis of 2 LSB.}
Regardless of the programmed incremental resolution, the hysteresis of 2 LSB always corresponds to the highest
h _{resolution of 10 bit. In absolute terms, the hysteresis is set to 0.704 degrees for all resolutions.}
For constant rotational directions, every magnet position change is indicated at the incremental outputs (see
c _{Figure 9). If for example the magnet turns clockwise from position „x+3“ to „x+4“, the incremental output would also}
indicate this position accordingly.
e _{A change of the magnet’s rotational direction back to position „x+3“ means, that the incremental output still remains}
T^{unchanged for the duration of 2 LSB, until position „x+2“ is reached. Following this direction, the incremental outputs}
will again be updated with every change of the magnet position.
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