Technical Note
19/21
BD88400GUL,BD88410GUL,BD88415GUL,BD88420GUL
www.rohm.com 2011.03 – Rev. A
© 2011 ROHM Co., Ltd. All rights reserved.
●Notes for use
(1) Absolute Maximum Ratings
An excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc.,
can break down devices, thus making impossible to ide ntify breaking mode such as a short circuit or an open circuit. If
any special mode exceeding the absolute maximum ratings is assumed, consid eration should b e given to take physical
safety measures including the use of fuses, etc.
(2) Operating conditions
These conditions represent a range within which characteristics can be provided approximately as expected. The
electrical characteristics are guara nteed under the conditions of each parameter.
(3) Reverse connection of power supply connector
The reverse connection of power supply connector can break down ICs. Take protective measures against the
breakdown due to the revers e connection, such as mounting a n external diode bet ween the power supply and the IC ’s
power supply terminal.
(4) Power supply line
Design PCB pattern to provide low impedance for the wiring between the power supply and the GND lines. In this
regard, for the digital block power supply and the analog block power supply, even though these power supplies has
the same level of potential, separate the power supply pattern for the digital block from that for the analog block, thus
suppressing the diffraction of digital noises to the analog block po wer supply resultin g from impedance common to the
wiring patterns. For the GND line, give consideration to design the patterns in a similar manner.
Furthermore, for all power supply terminals to ICs, mount a capacitor between the power supply and the GND terminal.
At the same time, in order to use an electrolytic capacitor, thoroughly check to be sure the characteristics of the
capacitor to be used present no problem including the occurrence of capacity dropout at a low temperature, thus
determining the constant.
(5) GND voltage
Make setting of the potential of the GND terminal so that it 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.
(6) Short circuit between terminals and erroneous mountin g
In order to mount ICs on a s et PCB, pay thorough atte ntion 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.
(7) Operation in strong electromagnetic field
Be noted that using ICs in the strong electromagnetic field can malfunction them.
(8) 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.
(9) Input terminals
In terms of the construction of IC, parasitic elements are inevitably formed in re lation to potential. The operati on 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. Furthermore, do not
apply a voltage to the inp ut terminals when no power supp ly voltage is applied to the IC. In ad dition, even if the power
supply voltage is applied, apply to the input terminals a voltage lower than the power supply voltage or within the
guaranteed value of electrical characteristics.
(10) Ground wiring pattern
If small-signal GND and large-current GND are provided, It will be recommended to separate the large-current GND
pattern from the small-signal GND pattern and establish a single ground at the reference point of the set PCB so that
resistance to the wiring pattern and voltage fluctuations due to a l arge current will cause no fluctuations in voltages of
the small-signal GND. Pay attention not to cause fluctuations in the GND wiring pattern of external parts as well.
(11) External capacitor
In order to use a ceramic capacitor as the external capacitor, determine the constant with consideration given to a
degradation in the nomi nal capacitance due to DC bias and changes in the capacitance due to temperature, etc.
(12) About the rush current
For ICs with more than one power supply, it is possible that rush current may flow instantaneously due to the internal
powering sequence and delays. Therefore, give special consideration to power coupling capacitance, power wiring,
width of GND wiring, and routing of wiring.