AS5040 datasheet(6/28 Pages) AMSCO

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AS5040 10-BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER

Revision 1.6, 03-Oct-06

www.austriamicrosystems.com

Page 6 of 28

Even

PAR

CSn

CLK

COF

LIN

OCF

Mag

INC

Mag

DEC

CLK FE

Angular Position Data

Status Bits

CLK/2

DO active

DO valid

D8 D7

1st Device

2nd Device

Angular Position Data

Figure 6: Daisy Chain mode data transfer

Incremental Outputs

Three different incremental output modes are possible

with quadrature A/B being the default mode.

Figure 7 shows the two-channel quadrature as well as

the step / direction incremental signal (LSB) and the

direction bit in clockwise (CW) and counter-clockwise

(CCW) direction.

5.1

Quadrature A/B Output

(Quad A/B Mode)

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) by 90 electrical degrees. Channel B leads channel

A at a counter-clockwise rotation.

5.2

LSB Output (Step / Direction Mode)

Output LSB reflects the LSB (least significant bit) of the

programmed incremental resolution (OTP Register Bit

Div0, Div1). Output Dir provides information about the

rotational direction of the magnet, which may be placed

above or below the device (1=clockwise; 0=counter

clockwise; top view). Dir is updated with every LSB

change.

In both modes (quad A/B, step/direction) the resolution

and the index output are user programmable. The index

pulse indicates the zero position and is by default one

angular step (1LSB) wide. However, it can be set to three

LSBs by programming the Index-bit of the OTP register

accordingly (see Table 6).

Counterclockwise ccw

Step / Dir-Mode

Quad A/B-Mode

Index=0

1LSB

Index=1

3 LSB

Ind ex

Mechanical

Zero Position

LSB

Dir

Rotation Direction

Change

CSn

t Incremental outputs valid

t Dir valid

Hyst =

2 L S B

Clockwise cw

Mechanical

Zero Position

Figure 7: Incremental output modes

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