DYNAMIC, PEAK-DETECTING,

DIFFERENTIAL HALL-EFFECT

GEAR-TOOTH SENSORS

115 Northeast Cutoff, Box 15036

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

12

APPLICATIONS INFORMATION — Continued

continued next page…

Signal Duty Cycle. For repetitive target structures,

precise duty cycle is maintained over the operating air gap

and temperature range due to an extremely good symme-

try in the magnetic switch points of the device. For

nonrepetitive target structures, there will be a small but

measureable change in pulse width versus air gap.

Output Polarity. The output of the device will switch from

HIGH to LOW as the leading edge of the target passes

the module in the direction indicated below (pin 4 to pin

1), which means that the output will be LOW when the unit

is facing a tooth. If rotation is in the opposite direction

(pin 1 to pin 4), the output of the device will switch from

LOW to HIGH as the leading edge of the target passes

the module, which means that the output will be HIGH

when the unit is facing a tooth.

Dwg. AH-006-1

1

2

3

4

Power Supply Protection. The sensor contains an on-

chip voltage regulator and can operate over a wide supply

voltage range. For devices that need to operate from an

unregulated power supply, transient and double-battery

protection should be added externally. For applications

using a regulated supply, external EMI/RFI protection is

often required. Insufficient protection can result in unex-

plained pulses on the output line, providing inaccurate

sensing information to the user.

The filter capacitor and EMI protection circuitry can

easily be added to a PC board for use with these devices.

Provisions have been made for simple mounting of a

board on the back of the unit.

Dwg. AH-007

1

2

3

4

Operation From a Regulated Power Supply. These

devices require minimal protection circuitry during opera-

tion from a low-voltage regulated line. The on-chip

voltage regulator provides immunity to power supply

variations between 3.5 V and 16 V. However, even while

operating from a regulated line, some supply and output

filtering is required to provide immunity to coupled and

injected noise on the supply line. A basic RC low-pass

circuit (R1C1) on the supply line and an optional output

capacitor (C2) is recommended for operation in noisy

environments. Because the device has an open-collector

output, an output pull-up resistor (RL) must be included

either at the sensor output (pin 2) or by the signal proces-

sor input.

3

X

X

Dwg. EH-008-1A

+

-

12

4

Vcc

20

Ω

R L

0.033

µF

0.22

µF

100 pF

OUTPUT

SUPPLY

C3

C2

C 1

R 1