A1140/41/42/43
Sensitive Two-Wire Chopper-Stabilized Unipolar Hall Effect Switches
Application Information
For additional general application information, visit the Allegro
MicroSystems Web site at www. allegromicro.com.
Typical Application Circuit
The A114x family of devices must be protected by an external
bypass capacitor, C
BYP
, connected between the supply, VCC,
and the ground, GND, of the device. C
BYP
reduces both external
noise and the noise generated by the chopper-stabilization func-
tion. As shown in
fi
gure 3, a 0.01 µF capacitor is typical.
Installation of C
BYP
must ensure that the traces that connect it to
the A114x pins are no greater than 5 mm in length.
All high-frequency interferences conducted along the supply
lines are passed directly to the load through C
BYP
, and it serves
only to protect the A114x internal circuitry. As a result, the load
ECU (electronic control unit) must have sufficient protection,
other than C
BYP
, installed in parallel with the A114x.
A series resistor on the supply side, R
S
(not shown), in combi-
nation with C
BYP
, creates a
fi
lter for EMI pulses. (Additional
information on EMC is provided on the Allegro MicroSystems
Web site.)
When determining the minimum V
CC
requirement of the A114x
device, the voltage drops across R
S
and the ECU sense resistor,
R
SENSE
, must be taken into consideration. The typical value for
R
SENSE
is approximately 100
Ω.
GND
A
A
B
Package UA Only
Maximum separation 5 mm
V+
VCC
B
A114x
C
BYP
0.01 uF
GND
B
R
SENSE
ECU
Figure 3. Typical application circuit
A1140-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
8
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