AS5035 – 64 PPR INCREMENTAL MAGNETIC ROTARY ENCODER

Revision 1.5

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5.5

MagInc and MagDec Indicators

These two pins are open-drain outputs with a maximum

driving capability of 2mA @ 3.0V and 4mA @ 4.5V.

MagINC, (Magnitude Increase) turns on, when the magnet

is pushed towards the IC, thus when the magnetic field

strength is increasing.

MagDEC, (Magnitude Decrease) turns on, when the

magnet is pulled away from the IC, thus when the magnetic

field strength is decreasing.

If both outputs are low, they indicate that the magnetic

field out of the allowed range:

MagINC

MagDEC

Description

off

off

No distance change. Magnetic Input Field OK

off

on

Distance increase (Magnet pulled away from IC)

on

off

Distance decrease (Magnet pushed towards IC)

on

on

Magnetic Input Field invalid – out of range:

either too large (magnet too close) or too small (missing magnet or magnet too far away)

Table 2: Magnetic field strength diagnostic outputs

off = open-drain output transistor is off. Using a pull-up resistor, the output is high

on = open-drain output transistor is on. Using a pull-up resistor, the output is low

Both outputs MagInc and MagDec may be tied together, using one common pull-up resistor. In this case, the output will be high

only when the magnetic field is in range. It will be low when either the magnet is moving in Z-axis or when the magnetic field is

out of range.

6

Incremental Outputs

6.1

A, B and Index

The phase shift between channel A and B indicates the

direction of the magnet movement. Channel A leads

channel B at a clockwise rotation of the magnet (top view,

magnet placed above or below the device) with 90

electrical degrees. Channel B leads channel A at a

counter-clockwise rotation. The Index pulse has a width of

1LSB = 1.4°

6.2

Hysteresis

To avoid flickering of the incremental outputs at a

stationary mechanical position, a hysteresis of 0.7° is

introduced. When the direction of rotation is reversed, the

incremental outputs will not change state unless the

movement in the opposite direction is larger than the

hysteresis. This leads to the effect that the A,B and Index

pulse positions will be shifted by 0.7° when the rotational

direction is reversed. This shift is cancelled again with the

next reversal of direction so that the A,B and Index pulses

appear always at the same position for a given rotational

direction no matter how often the rotational direction is

reversed (see Figure 5).

.

A

B

Index=

1.40625°

Index

Mechanical

Zero Position

Rotation Direction

Change

CSn

Hysteresis =0.7°

Mechanical

Zero Position

power-up

1.40625°

=90e°

5.625°

=360e°

Figure 5: Incremental quadrature outputs