A1140, A1141,
A1142, and A1143
Sensitive Two-Wire Chopper-Stabilized
Unipolar Hall Effect Switches
Functional Description
Operation
The output, I
CC
, of the A1140 and A1142 devices switch low
after the magnetic field at the Hall sensor exceeds the operate
point threshold, B
OP
. When the magnetic field is reduced to
below the release point threshold, B
RP
, the device output goes
high. The differences between the magnetic operate and release
point is called the hysteresis of the device, B
HYS
. 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 B
OP
and B
RP
values, in comparison to the A1140 and
A1142 (see figure 1).
I+
I
CC(H)
I+
I
CC(H)
Switch to High
I
CC(L)
0
Switch to High
Switch to Low
Switch to Low
I
CC
I
CC
B
RP
B
HYS
B
HYS
(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).
B
OP
B–
B+
0
I
CC(L)
B–
B+
B
RP
B
OP
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
7
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
