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AS5140H

Data Sheet - D e t a i l e d D e s c r i p t i o n

the chain (see Figure 6). During programming (see Programming the AS5140H on page 19), a programming voltage of 7.5V must be applied to

pin Prog. This voltage level exceeds the limits for pin DO, so one of the following precautions must be made during programming:

Open the connection

during programming, (or)

Add a Schottky diode between DO and Prog (Anode = DO, Cathode = Prog)

Due to the parallel connection of CLK and CSn, all connected devices may be programmed simultaneously.

7.2 Incremental Outputs

Three different incremental output modes are possible with quadrature A/B being the default mode. Figure 8 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.

7.2.1 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.

Figure 8. Incremental Output Modes

7.2.2 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 20).

DO

Prog

→

LSB

Dir

CSn

Clockwise cw

Counterclockwise ccw

Index

Step / Dir-Mode

B

A

Quad A/B-Mode

Index=1

3 LSB

Index=0

1 LSB

Hyst=

2LSB

Mechanical

Zero Position

Mechanical

Zero Position

Rotation Direction

Change