A1140, A1141,
A1142, and A1143
Sensitive Two-Wire Chopper-Stabilized
Unipolar Hall Effect Switches
Application Information
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 figure 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, RS (not shown), in combina-
tion with C
BYP
, creates a filter for EMI pulses.
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.
ECU
GND
A
A
B
Package UA Only
Maximum separation 5 mm
V+
VCC
B
A114x
C
BYP
0.01
μF
GND
B
R
SENSE
Figure 3. Typical application circuit
For additional general application information, visit the Allegro
Web site at www. allegromicro.com.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
9
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
