BU21072MUV_16 Datasheet, PDF (30/40 Pages) Rohm – Capacitive Switch Controller ICs

BU21072MUV / BU21078MUV / BU21078FV
Operational Notes
(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 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) Operating conditions
These conditions represent a range within which characteristics can be provided approximately as expected. The
electrical characteristics are guaranteed 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 reverse connection, such as mounting an external diode between 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 power supply resulting 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 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.
(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 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.
Furthermore, do not apply a voltage to the input terminals when no power supply voltage is applied to the IC. In
addition, 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.
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TSZ02201-0L5L0F300640-1-2
14.Jul.2016 Rev.004