Highly Programmable, Back-Biased,

Hall-Effect Switch with TPOS Functionality

ATS128LSE

20

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

B+

B–

Target Displacement from Home Position,

0

–θθ

Home

Position

Displaced

Clockwise

Displaced

Counterclockwise

Figure 15 shows a plot of the example, indicating magnetic field

density versus displacement, at a fixed air gap. For the example,

the magnetic field is assumed to be positive (south). At the Home

low (assuming POL = 0) . In a position at a displacement greater

that the sensor IC changes state from low to high at ±θ.

First, the target is located at the corresponding switchpoint loca-

tion, the –θ° or +θ° position. Next, the device Positive Trim, Up-

Counting register is selected and the output is monitored while

the addressed code is increased. When the register is entered, the

changes state from low to high. The code value when the device

this for later reference). (See B in figure 16.)

Trim, Down-Counting register is selected, and the output is moni-

tored while the addressed code is increased. When the register

for down-counting) and output is high. (See C in figure 17.)

Figure 15. Example of magnetic flux density versus target displacement. In an

application, an increasing B value could indicate either an increasing intensity of a

south field or a decreasing intensity of a north field.