Technical Note

31/32

BH1771GLC

www.rohm.com

2011.06 - Rev.B

© 2011 ROHM Co., Ltd. All rights reserved.

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Cautions on use

1)

Absolute Maximum Ratings

An excess in the absolute maximum ratings, such as supply voltage ( Vccmax, VSDAmax, VSCLmax, VINTmax,

VGNDNCmax, VLEDmax ), temperature range of operating conditions ( Topr ), etc., can break down devices, thus making

impossible to identify breaking mode such as a short circuit or an open circuit. If any special mode exceeding the absolute

maximum ratings is assumed, consideration should be given to take physical safety measures including the use of fuses,

etc.

2)

GND voltage

Make setting of the potential of the GND terminal and GND_LED terminal so that they will be maintained at the minimum in

any operating state. Furthermore, check to be sure no terminals are at a potential lower than the GND voltage including an

actual electric transient.

3)

Short circuit between terminals and erroneous mounting

In order to mount ICs on a set PCB, pay thorough attention to the direction and offset of the ICs. Erroneous mounting can

break down the ICs. Furthermore, if a short circuit occurs due to foreign matters entering between terminals or between

the terminal and the power supply or the GND terminal, the ICs can break down.

4)

Operation in strong electromagnetic field

Be noted that using ICs in the strong electromagnetic field can malfunction them.

5)

Inspection with set PCB

On the inspection with the set PCB, if a capacitor is connected to a low-impedance IC terminal, the IC can suffer stress.

Therefore, be sure to discharge from the set PCB by each process. Furthermore, in order to mount or dismount the set

PCB to/from the jig for the inspection process, be sure to turn OFF the power supply and then mount the set PCB to the jig.

After the completion of the inspection, be sure to turn OFF the power supply and then dismount it from the jig. In addition,

for protection against static electricity, establish a ground for the assembly process and pay thorough attention to the

transportation and the storage of the set PCB.

6)

Input terminals

In terms of the construction of IC, parasitic elements are inevitably formed in relation to potential. The operation of the

parasitic element can cause interference with circuit operation, thus resulting in a malfunction and then breakdown of the

input terminal. Therefore, pay thorough attention not to handle the input terminals; such as to apply to the input terminals a

voltage lower than the GND respectively, so that any parasitic element will operate. In addition, apply to the input terminals

a voltage within the guaranteed value of electrical characteristics.

7)

Thermal design

Perform thermal design in which there are adequate margins by taking into account the power dissipation ( Pd ) in actual

states of use.

8)

Treatment of package

Dusts or scratch on the photo detector may affect the optical characteristics. Please handle it with care.

9)

RUSH current

When power is first supplied to the CMOS IC, it is possible that the internal logic may be unstable and rush current may

flow instantaneously. Therefore, give special consideration to power coupling capacitance, power wiring, width of GND

wiring, and routing of connections.