Sensitive Two-Wire Chopper-Stabilized
Unipolar Hall Effect Switches
A1140, A1141,
A1142, and A1143
Application Information
Typical Application Circuit
The A114x family of devices must be protected by an external
bypass capacitor, CBYP, connected between the supply, VCC,
and the ground, GND, of the device. CBYP 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.
V+
VCC
B
A114x
C
BYP
Installation of CBYP must ensure that the traces that connect it to
the A114x pins are no greater than 5 mm in length.
0.01 μF
GND
GND
B
All high-frequency interferences conducted along the supply
lines are passed directly to the load through CBYP, 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 CBYP, installed in parallel with the A114x.
A
A
B
Package UA Only
Maximum separation 5 mm
RSENSE
A series resistor on the supply side, RS (not shown), in combina-
tion with CBYP, creates a filter for EMI pulses.
When determining the minimum VCC requirement of the A114x
device, the voltage drops across RS and the ECU sense resistor,
RSENSE, must be taken into consideration. The typical value for
RSENSE is approximately 100 Ω.
ECU
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
9
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
