A3282LUA 查看數據表（PDF） - Allegro MicroSystems

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A3282LUA

Chopper-Stabilized Hall Effect Latch

Allegro MicroSystems 

A3282

Chopper-Stabilized Hall Effect Latch

Functional Description

Operation

The output of these devices switches low (turns on) when a

magnetic field perpendicular to the Hall sensor exceeds the

operate point threshold, BOP. After turn-on, the output voltage

is VOUT(SAT). The output transistor is capable of sinking current

up to the short circuit current limit, IOM, which is a minimum of

30 mA. Note that the device latches, that is, a south pole of suffi-

cient strength towards the branded surface of the device turns the

device on. The device remains on if the south pole is removed.

When the magnetic field is reduced below the release point, BRP,

the device output turns off (goes high). The difference in the

magnetic operate and release points is the hysteresis, BHYS , of

the device. This built-in hysteresis allows clean switching of the

output even in the presence of external mechanical vibration and

electrical noise.

Powering-on the device in the hysteresis region (less than BOP and

higher than BRP) allows an indeterminate output state. The correct

state is attained after the first excursion beyond BOP or BRP.

Applications

It is strongly recommended that an external bypass capacitor be

connected (in close proximity to the Hall sensor) between the

supply and ground of the device to reduce both external noise

and noise generated by the chopper stabilization technique. As is

shown in Panel B of figure 1, a 0.1µF capacitor is typical.

Extensive applications information on magnets and Hall-effect

sensors is available in:

• Hall-Effect IC Applications Guide, AN27701,

• Hall-Effect Devices: Gluing, Potting, Encapsulating, Lead

Welding and Lead Forming, AN27703.1

• Soldering Methods for Allegro’s Products – SMT and Through-

Hole, AN26009

All are provided in Allegro Electronic Data Book, AMS-702 and

the Allegro Web site: www.allegromicro.com

(A)

V+

VCC

0

B–

0

BHYS

VOUT(SAT)

B+

(B)

VS

VCC

CBYP

0.1 µF

A3282

VOUT

GND

RLOAD

Sensor Output

Figure 1: Switching Behavior of Latches. In Panel A, on the horizontal axis, the B+ direction indicates increasing south polarity magnetic

field strength, and the B– direction indicates decreasing south polarity field strength (including the case of increasing north polarity). This

behavior can be exhibited when using a circuit such as that shown in panel B.

A3282-DS

Allegro MicroSystems, Inc.

7

115 Northeast Cutoff, Box 15036

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

www.allegromicro.com

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