NR263S Datasheet, PDF (24/29 Pages) Sanken electric – Light Load High Efficiency Synchronous Buck Regulator IC

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8.3.3 Attention about the insertion of the bead-core
Fig. 8-10 Bead core insertion prohibited area
In the area surrounded by the red dotted line within the Fig8-12, don’t insert the bead-core such as Ferrite-bead.
As for the pattern-design of printed-circuit-board, it is recommended that the parasitic-inductance of wiring-pattern
is made small for the safety and the stability.
When bead-core was inserted, the inductance of the bead-core is added to parasitic-inductance of the wiring-pattern.
By this influence, the surge-voltage occurs often, or , AGND & PGND of IC becomes unstable, and also, negative
voltage occurs often.
Because of this, faulty operation occurs in the IC. The IC has the possibility of damage in the worst case.
About the Noise-reduction, fundamentally, Cope by “The addition of BS serial resistor” and “The addition of CR
snubber circuit”.
8.3.4 Reverse Bias Protection
A diode for reverse bias protection may be required
between input and output in case the output voltage is
expected to be higher than the input Pin voltage
(a common case in battery charger applications).
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Fig. 8-11 Reverse bias protection diode
8.3.5 Overvoltage protection of VO terminal
If the hot-swap is done by such as load-line connector when the DC / DC converter circuit is in operation, the surge
voltage due to hot-swap will occur on the Vo output circuit. In your use condition, please be careful so that the
voltage applied to the VO terminal does not exceed the absolute maximum rating (6V). For problems such as the
reverse-flow from the external circuit, please take measures. Nevertheless, if you can not suppress an overvoltage
factors by the surge voltage such as when the hot-swap was done, please protect the VO terminal by inserting the
R_VO as shown in Fig8-14. The resistance of R_VO as a guide is defined as 100Ω. And, by inserting of the R_VO
(= 100Ω) to the sensing line, the output voltage V_O(=5V(typ)) will rise further +5mV equivalent.
NR263S series-DSE Rev.1.0
SANKEN ELECTRIC CO.,LTD
24
2016.03.09
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2016