NR263S Datasheet, PDF (23/29 Pages) Sanken electric – Light Load High Efficiency Synchronous Buck Regulator IC

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Notes:
1) Dimension is in millimeters, *Dimensions in brackets are in inches
2) Drawing is not to scale
Fig. 8-7 Foot printing for SOP8(recommended land Pad)
8.3 Applied Design
8.3.1 Spike Noise Reduction(1)
The addition of the BS serial resistor
The “turn-on switching speed” of the internal
Power-MOSFET can be slowed down by inserting R_BS
(option) of the Fig8-10.It is tendency that Spike noise
becomes small by reducing the switching-speed. Set
up 10-ohm as an upper limit when you use R_BS.
*Attention
1) When the resistance value of R_BS is enlarged by
mistake too much, the internal power-MOSFET
becomes an under-drive,it may be damaged worst.
2) The “defective starting-up” is caused when the
resistance value of R_BS is too big.
*The BS serial resistor R_BS is R3 in the Demonstration
Board.
R_BS
BS
C_BS
SW
NR263S
Fig. 8-8 The addition of the BS serial resistor
8.3.2 Spike Noise Reduction(2)
The addition of the Snubber circuit
In order to reduce the spike noise, it is possible to
compensate the output waveform and the recovery time
of internal parasitic diode by connecting a capacitor and
resistor parallel to the internal parasitic diode (snubber
method). This method however may slightly reduce the
efficiency.
* For observing the spike noise with an oscilloscope,
the probe lead (GND) should be as short as possible and
connected to the root of output capacitor. If the probe
GND lead is too long, the lead may act like an antenna
and the observed spike noise may be much higher and
may not show the real values.
*The snubber circuit parts are C13 and R10.
IN
SW
NR263S
PGND
≒10Ω
*Option
≒1000pF
Fig. 8-9 The addition of the Snubber circuit
NR263S series-DSE Rev.1.0
SANKEN ELECTRIC CO.,LTD
23
2016.03.09
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2016