bd8671kn ROHM Co. Ltd., bd8671kn Datasheet - Page 4

• Manufacturer Part Number: bd8671kn
• Description: Dc/dc Converter Ic For Camera Module For Car Navigation System
• Manufacturer: ROHM Co. Ltd.

◎NOTE ON USE
1．About the absolute maximum rating
2．About the reverse-connection of the power supply connector
3．Power supply line
4．About grand potential
5．About the heat design
6．About the short and the miss-installation between terminals
7．About operation in strong electromagnetic field
8．About the capacitor during output-GND
9．About the inspection by the set substrate
10．About each input terminal
11．Earth wiring pattern
12．Thermal Shut-Down
13．DC/DC converter control terminal (CTL1,2,3)
Attention is brushed off enough to the quality control, it is likely to destroy when the absolute maximum rating such as impressed voltages (VCC_IN,DCIN) and
ranges (Topr) of the operating temperature as it is exceeded, the mode of breakings of the short or the opening, etc. cannot be specified, and examine it in this
IC to give physical measures for safety such as fuses when a special mode that exceeds the absolute maximum rating is assumed.
IC might destroy it by reversely connecting the power supply connector. Give measures such as putting the diode between power supply terminals of power
supply and IC outside for the reverse-touching destruction protection.
Please do measures such as putting the bypass capacitor in power supply-GND nearest pin of this IC as the route of the resurrection current to cause the
return of the current in which it resurrected it by the counter electromotive force of the coil.
Please confirm the characteristic of the electrolytic capacitor enough as the capacity omission etc. at the low temperature never happen, and decide it.
Any state of operation must become the lowest potential about the potential of the terminal GND. Moreover, confirm whether there is terminal that is actually the
voltage of GND or less including transients.
Think about permissible loss (Pd) in an actual state of use, and do the heat design with the margin enough.
Note the direction and the miss-registration of IC enough when you install it in the set substrate. IC might destroy it as well as reversely connecting the power
supply connector when installing it by mistake. Moreover, there is fear of destruction when the foreign body enters between terminals, the terminal, the power
supply, and grandeur and it is short-circuited.
In use in strong electromagnetic field, note that there is a possibility of malfunctioning.
The current charged the capacitor with when VCC is 0V or is GND and is short-circuited when a big capacitor is connected between GND output by some
factors flows into the output and it is likely to destroy it. Give the capacitor between GND output to 0.1μF or less.
It is likely to suffer stress to IC and discharge electricity every one process when you connect the capacitor with the pin with low impedance when inspecting it in
the set substrate. Moreover, detach it after connecting after the power supply is turned off without fail when detaching it to G in the inspection process,
inspecting, and turning off the power supply. n addition, be give the earth to the assembly process as a static electricity measures, and careful enough when it
transports and you preserve it.
This IC is a monolithic IC which has a P
This P layer and an N layer in each element form a PN junction to construct various parasitic elements.
For instance, the potential difference operates in resistance as shown in the figure below when resistance and the transistor connect it with the terminal and the
playground (GND) >(terminal B) joint of PN operates as a parasitic diode in playground (GND) >(terminal A) transistor (NPN). In addition, the NPN transistor of
parasitism works with N layer of the element of the above-mentioned parasitic diode and the neighborhood and others in transistor (NPN). A parasitic element
in IC composition is inevitably formed because of the potential relation.
A parasitic element can operate, the interference with the circuit operation be caused, it malfunction, and, consequently, it cause destruction. Therefore, do not
do the usage that a parasitic element operates as a voltage that is lower than the playground (GND;P substrate) is impressed to the input terminal enough.
Moreover, do not impress the voltage to the input terminal when you do not impress the power-supply voltage to IC. Give each input terminal to me the voltage
below the power-supply voltage or in the guarantee value of an electric characteristic when you similarly impress the power-supply voltage.
If small signal GND and large current GND exist, disperse their pattern. In addition, for voltage change by pattern wiring impedance and large current not to
change voltage of small signal GND, each ground terminal of IC must be connected at the one point on the set circuit board. As for GND of external parts, it is
similar to the above-mentioned.
When a thermal shutdown operates, the DC/DC converter controller of all Ch is turned off. When a thermal shutdown is released, the DC/DC converter
controller of all Ch becomes an operation beginning from turning off.
This IC has 3 output voltage (3.3V,12.0V,-5.0V). When you turning off control 12.0V output from all output ON(CTL1,2,3=H) time with the terminal CTL2,
please control 12.0V output turning off with the terminal CTL2 after 200μs or more has passed by the terminal CTL3 since -5.0 the V output was turning off
controlled.
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isolations and P substrate to isolate elements each other.
Example of IC of simple structure
REV. A
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