AS5140H datasheet(21/55 Pages) AMSCO

21 / 55 page

ams Datasheet

Page 21

[v1-09] 2018-Feb-20

Document Feedback

AS5140H − Detailed Description

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

Incremental Power-up Lock Option. 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: CSn has an internal pull-up resistor

and must be externally pulled low (Rext ≤ 5KΩ). If Csn is

low at power-up, 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 waiting

time at power-up. Instead of waiting for the specified

maximum power up-time (0), the controller can start

requesting data from the AS5140H as soon as the state

(A=B=Index = high) is cleared.

• CSn = high or open at power-up: 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 system microcontroller is

ready to receive data.

Incremental Output Hysteresis

To avoid flickering incremental outputs at a stationary magnet

position, a hysteresis is introduced. 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

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 Figure 27). For example, if the magnet

turns clockwise from position “x+3“ to “x+4“, the incremental

output would also indicate this position accordingly. A change

of the magnet’s rotational direction back to position “x+3”

means that the incremental output still remains 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.

AS5140H Datasheet(PDF) 21 Page - ams AG

AS5140H Datasheet(HTML) 21 Page - ams AG

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

Datasheet Download

Link URL