Sensitive Two-Wire Chopper-Stabilized
Unipolar Hall Effect Switches
A1140, A1141,
A1142, and A1143
Functional Description
Operation
The output, ICC, of the A1140 and A1142 devices switch low
after the magnetic field at the Hall sensor exceeds the operate
point threshold, BOP. When the magnetic field is reduced to
below the release point threshold, BRP, the device output goes
high. The differences between the magnetic operate and release
point is called the hysteresis of the device, BHYS. This built-
in hysteresis allows clean switching of the output even in the
presence of external mechanical vibration and electrical noise.
The A1141 and A1143 devices switch with opposite polarity for
similar BOP and BRP values, in comparison to the A1140 and
A1142 (see figure 1).
I+
I+
ICC(H)
ICC(H)
ICC(L)
ICC(L)
0
0
B+
B–
B+
B–
BHYS
BHYS
(A) A1140, A1142
(B) A1141, A1143
Figure 1. Alternative switching behaviors are available in the A114x device family. On the horizontal axis, the B+ direction indicates
increasing south polarity magnetic field strength, and the B– direction indicates decreasing south polarity field strength (including the
case of increasing north polarity).
Allegro MicroSystems, Inc.
7
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
