Technical Note
28/29
BUTA2WNVX series, BUTA2WHFV series
www.rohm.com
2011.01 - Rev.C
2011 ROHM Co., Ltd. All rights reserved.
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Notes for use
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About absolute maximum rating
Breakage may occur when absolute maximum ratings such as applied voltage and operating temperature range are
exceeded. Short mode or open mode cannot be specified at occurrence of a break, so please prepare physical safety
measures (e.g., fuse) if such special mode in which the absolute maximum rating is exceeded can be assumed.
·
About GND potential
Please be sure that the potential of the GND terminal is the lowest in any operating condition.
·
About thermal design
Please provide thermal design with sufficient margin, taking power dissipation (Pd) in actual usage conditions into
consideration.
·
About short between pins and misattachment
Please be careful regarding the IC direction and misalignment at attachment onto a printed circuit board. Misattachment
may cause a break of IC. Short caused by foreign matter between outputs, output and power supply, or GNDs may also
lead to a break.
·
About operation in a strong electromagnetic field
Please note that usage in a strong electromagnetic field may cause malfunction.
·
About common impedance
Please give due consideration to wiring of the power source and GND by reducing common-mode ripple or making ripple
as small as possible (e.g., making the wiring as thick and short as possible, or reducing ripple by L
C), etc.
·
About STBY terminal voltage
Set STBY terminal voltage to 0.3 V or less to put each channel into a standby state and to 1.5 V or more to put each
channel into an operating state. Do not fix STBY terminal voltage to 0.3 V or more and 1.5 V or less or do not lengthen
the transition time. This may cause malfunction or failure. When shorting the VIN terminal and STBY terminal for usage,
the status will be “STBY=VIN=LOW” at turning the power OFF, and discharge of the VOUT terminal cannot operate,
which means voltage may remain for a certain time in the VOUT terminal. Since turning the power ON again in this state
may cause overshoot, turn the power ON for use after the VOUT terminal is completely discharged.
·
About overcurrent protection circuit
Output has a built-in overcurrent protection circuit, which prevents IC break at load short. Note that this protection circuit
is effective for prevention of breaks due to unexpected accidents. Please avoid usage by which the protection circuit
operates continuously.
·
About thermal shutdown
Output is OFF when the thermal circuit operates since a temperature protection circuit is built in to prevent thermal
breakdown. However, it recovers when the temperature returns to a certain temperature. The thermal circuit operates at
emergency such as overheating of IC. Since it is prepared to prevent IC breakdown, please do not use it in a state in
which protection works.
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About reverse current
For applications on which reverse current is assumed to flow into IC,
it is recommended to prepare a path to let the current out by putting
a bypass diode between the VIN-VOUT terminals.
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About testing on a set board
When connecting a capacitor to a terminal with low impedance for testing on a set board, please be sure to discharge for
each process since IC may be stressed. As a countermeasure against static electricity, prepare grounding in the assembly
process and take sufficient care in transportation and storage. In addition, when connecting a capacitor to a jig in a testing
process, please do so after turning the power OFF and remove it after turning the power OFF.
Fig.181 Example of bypass diode connection
Reverse current
VIN
GND
STBY
OUT