115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

ATS632LSA

HALL-EFFECT

GEAR-TOOTH SENSOR

SUBASSEMBLY

Additional applications Information on gear-tooth and

other Hall-effect sensors is provided in the Allegro Inte-

grated and Discrete Semiconductors Data Book or

Application Note 27701.

APPLICATIONS INFORMATION — Continued

3

12

4

Vcc

Dwg. EH-008-2A

20

Ω

RL

0.033

µF

100 pF

100 pF

OUTPUT

SUPPLY

0.1

µF

2.5 k

Ω

6.8 V

C3

C 2

C1

R 1

R Z

C S

X

Operation from an Unregulated Power Supply. In

applications where the device gets its power from an

unregulated supply such as an automotive battery, full

protection is generally required. In addition to supply

regulation, such applications require the device to with-

stand various supply side transients. Specifications for

such transients vary between car manufacturers and

protection circuit design should be optimized for each

application. In the circuit shown below, a simple Zener-

controlled regulator is constructed using discrete compo-

nents. 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 the susceptibility

to EMI/RFI. The NPN should be chosen with sufficiently

high forward breakdown voltage so as to hold off supply-

side transients. The series diode should be chosen with

sufficiently high reverse breakdown capabilities so as to

withstand the most negative transient. The current-limiting

resistor (RZ) and the Zener diode should be sized for

power dissipation requirements.