Technical Note

BU52002GUL,BU52003GUL,BU52012HFV,BU52013HFV

9/13

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2010.01 - Rev.B

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

BU52002GUL,BU52012HFV

BU52002GUL,BU52012HFV detects and outputs for the S-pole only. Since it is unipolar, it does not recognize the N-pole.

BU52003GUL,BU52013HFV

BU52003GUL,BU52013HFV detects and outputs for the N-pole only. Since it is unipolar, it does not recognize the S-pole.

The unipolar 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.

N-Pole

S-Pole

Flux

B

Low

Brp S

Bop S

0

High

N-Pole

Magnetic flux density [mT]

Fig.35

S-Pole Detection

Flux

High

High

OUT [V]

N

N

S

S

S

N

S-Pole

B

Bop N

Brp N

0

High

N-Pole

Magnetic flux density [mT]

Fig.36

N-Pole Detection

Flux

High

High

Low

OUT [V]

N

N

S

S

S

N

S-Pole

Flux