A1140/41/42/43
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
fi
eld at the Hall sensor exceeds the oper-
ate point threshold, B
OP
. When the magnetic
fi
eld 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
fi
gure 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
I
CC(L)
0
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
fi
eld strength, and the B– direction indicates decreasing south polarity
fi
eld strength (including the
case of increasing north polarity).
B
OP
B–
B+
B–
B+
B
RP
B
OP
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
6
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
