ATS611 View Datasheet(PDF) - Allegro MicroSystems
Part Name
Description
MFG CO.
'ATS611' PDF : 16 Pages View PDF
ATS610LSA AND ATS611LSB
DYNAMIC, PEAK-DETECTING,
DIFFERENTIAL HALL-EFFECT
GEAR-TOOTH SENSORS
APPLICATIONS INFORMATION — Continued
Operation From an Unregulated Power Supply. In
automotive applications, where the device receives its
power from an unregulated supply such as the battery, full
protection is generally required so that the device can
withstand the many supply-side transients. Specifications
for such transients vary between car manufacturers, and
protection-circuit design should be optimized for each
application. In the circuit below, a simple
Zener-controlled regulator is constructed using discrete
components. The RC low-pass filter on the supply line
(R1C1) and a low-value supply bypass capacitor (CS) can
be included, if necessary, so as to minimize susceptibility
to EMI/RFI. The npn transistor should be chosen with
sufficiently high forward breakdown voltage so as to
withstand supply-side transients. The series diode should
be chosen with sufficiently high reverse breakdown
capabilities so as to withstand the most negative tran-
sient. The current-limiting resistor (RZ) and the Zener
diode should be sized for power dissipation requirements.
Capacitor Requirements. The choice of the capacitor at
pin 3 (C3) defines the minimum operating speed of the
target. This capacitor (0.1 µF minimum) is required to
stabilize the internal amplifiers as well as to eliminate the
signal offsets. Typically, a 0.33 µF low-leakage ceramic
capacitor is recommended. Values greater than 0.47 µF
should not be used as this may cause high-speed perfor-
mance degradation.
Capacitor leakage current at pin 3 will cause degrada-
tion in the low-speed performance of the device. Excess
capacitor leakage can result in the sensor changing output
state without movement of the gear tooth being sensed.
In addition to the capacitor leakage, it is extremely impor-
tant to minimize the leakage at the PC board and between
the pins of the sensor. Up to 50 nA of external leakage
can be tolerated at the capacitor pin node to ground.
Choice of low-leakage-current potting compounds and the
use of clean PC board techniques are extremely impor-
tant.
SUPPLY
RL
OUTPUT
C2
100 pF
2.5 kΩ
RZ
0.033 µF
CS
20 Ω
R1
6.8 V
C1
0.033 µF
0.22 µF
C3
1
2
3
4
Vcc
+
X
X-
Additional applications Information on gear-tooth and
other Hall-effect sensors is provided in the Allegro Elec-
tronic Data Book AMS-702 or Application Note 27701.
Dwg. EH-008A
www.allegromicro.com
13
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