BU52004GUL, BU52014HFV

Technical Note

7/11

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2010.01 - Rev.D

© 2010 ROHM Co., Ltd. All rights reserved.

The OUT1 pin detects and outputs for the S-pole only. Since it is unipolar, it does not recognize the N-pole.

The OUT2 pin detects and outputs for the N-pole only. Since it is unipolar, it does not recognize the S-pole.

The dual output Omnipolar detection Hall IC detects magnetic fields running perpendicular to the top surface of the package.

There is an inverse relationship between magnetic flux density and the distance separating the magnet and the Hall IC:

when distance increases magnetic density falls. When it drops below the operate point (Bop), output goes HIGH. When the

magnet gets closer to the IC and magnetic density rises, to the operate point, the output switches LOW. In LOW output

mode, the distance from the magnet to the IC increases again until the magnetic density falls to a point just below Bop, and

output returns HIGH. (This point, where magnetic flux density restores HIGH output, is known as the release point, Brp.)

This detection and adjustment mechanism is designed to prevent noise, oscillation and other erratic system operation.

Flux

B

Low

Brp S

Bop S

0

High

N-Pole

Magnetic flux density [mT]

Flux

High

High

OUT 1[V]

N

N

S

S

S

N

S-Pole

OUT1

Fig.23 S-Pole Detection

Flux

B

Bop N

Brp N

0

High

N-Pole

Magnetic density [mT]

Fig.24 N-Pole Detection

Flux

High

High

Low

OUT 2[V]

N

N

S

S

S

N

S-Pole

OUT2