Technical Note

BU52002GUL,BU52003GUL,BU52012HFV,BU52013HFV

8/13

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2010.01 - Rev.B

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

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Description of Operations

(Micropower Operation)

(Offset Cancelation)

(Magnetic Field Detection Mechanism)

The Hall IC cannot detect magnetic fields that run horizontal to the package top layer.

Be certain to configure the Hall IC so that the magnetic field is perpendicular to the top layer.

The unipolar detection Hall IC adopts an intermittent

operation method to save energy. At startup, the Hall

elements, amp, comparator and other detection circuits

power ON and magnetic detection begins. During standby,

the detection circuits power OFF, thereby reducing current

consumption. The detection results are held while standby

is active, and then output.

Reference period: 50ms (MAX100ms)

Reference startup time: 24μs

Standby

Startup time

Period

t

Fig.32

The Hall elements form an equivalent Wheatstone (resistor)

bridge circuit. Offset voltage may be generated by a

differential in this bridge resistance, or can arise from changes

in resistance due to package or bonding stress. A dynamic

offset cancellation circuit is employed to cancel this offset

voltage.

When Hall elements are connected as shown in Fig. 33 and a

magnetic field is applied perpendicular to the Hall elements,

voltage is generated at the mid-point terminal of the bridge.

This is known as Hall voltage.

Dynamic cancellation switches the wiring (shown in the figure)

to redirect the current flow to a 90˚ angle from its original path,

and thereby cancels the Hall voltage.

The magnetic signal (only) is maintained in the sample/hold

circuit during the offset cancellation process and then

released.

＋

GND

－

I

B

×

Hall Voltage

Fig.33

Fig.34

S

S

N

S

N

S

N

Flux

Flux