BU52004GUL, BU52014HFV

Technical Note

10/11

www.rohm.com

2010.01 - Rev.D

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

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Operation Notes

1) Absolute maximum ratings

Exceeding the absolute maximum ratings for supply voltage, operating conditions, etc. may result in damage to or

destruction of the IC. Because the source (short mode or open mode) cannot be identified if the device is damaged in this

way, it is important to take physical safety measures such as fusing when implementing any special mode that operates in

excess of absolute rating limits.

2) GND voltage

Make sure that the GND terminal potential is maintained at the minimum in any operating state, and is always kept lower

than the potential of all other pins.

3) Thermal design

Use a thermal design that allows for sufficient margin in light of the power dissipation (Pd) in actual operating conditions.

4) Pin shorts and mounting errors

Use caution when positioning the IC for mounting on printed circuit boards. Mounting errors, such as improper positioning or

orientation, may damage or destroy the device. The IC may also be damaged or destroyed if output pins are shorted

together, or if shorts occur between the output pin and supply pin or GND.

5) Positioning components in proximity to the Hall IC and magnet

Positioning magnetic components in close proximity to the Hall IC or magnet may alter the magnetic field, and therefore the

magnetic detection operation. Thus, placing magnetic components near the Hall IC and magnet should be avoided in the

design if possible. However, where there is no alternative to employing such a design, be sure to thoroughly test and

evaluate performance with the magnetic component(s) in place to verify normal operation before implementing the design.

6) Slide-by position sensing

Fig.29 depicts the slide-by configuration employed for position sensing. Note that when the gap (d) between the magnet and

the Hall IC is narrowed, the reverse magnetic field generated by the magnet can cause the IC to malfunction. As seen in

Fig.30, the magnetic field runs in opposite directions at Point A and Point B. Since the dual output Omnipolar detection Hall

IC can detect the S-pole at Point A and the N-pole at Point B, it can wind up switching output ON as the magnet slides by in

the process of position detection. Fig. 31 plots magnetic flux density during the magnet slide-by. Although a reverse

magnetic field was generated in the process, the magnetic flux density decreased compared with the center of the magnet.

This demonstrates that slightly widening the gap (d) between the magnet and Hall IC reduces the reverse magnetic field

and prevents malfunctions.

7) Operation in strong electromagnetic fields

Exercise extreme caution about using the device in the presence of a strong electromagnetic field, as such use may cause

the IC to malfunction.

8) Common impedance

Make sure that the power supply and GND wiring limits common impedance to the extent possible by, for example,

employing short, thick supply and ground lines. Also, take measures to minimize ripple such as using an inductor or

capacitor.

9) GND wiring pattern

When both a small-signal GND and high-current GND are provided, single-point grounding at the reference point of the set

PCB is recommended, in order to separate the small-signal and high-current patterns, and to ensure that voltage changes

due to the wiring resistance and high current do not cause any voltage fluctuation in the small-signal GND. In the same way,

care must also be taken to avoid wiring pattern fluctuations in the GND wiring pattern of external components.

10) Exposure to strong light

Exposure to halogen lamps, UV and other strong light sources may cause the IC to malfunction. If the IC is subject to such

exposure, provide a shield or take other measures to protect it from the light. In testing, exposure to white LED and

fluorescent light sources was shown to have no significant effect on the IC.

11) Power source design

Since the IC performs intermittent operation, it has peak current when it’s ON. Please taking that into account and under

examine adequate evaluations when designing the power source.

L

Fig.29

d

Magnet

Hall IC

Slide

-10

-8

-6

-4

-2

0

2

4

6

8

10

0

123

456

789

10

Horizontal distance from the magnet [mm]

Reverse

Fig.31

Fig.30

B

S

A

N

Flux

Flux