BD9763FVM Datasheet, PDF (5/12 Pages) Rohm – Single-output Step-up,High-efficiency Switching Regulator (Controller Type)

BD9763FVM
●Application example
VOUT
Technical Note
R1
R2
VCC
C1 ＊
VCC
OUT
RT
CTL/SS
＊RRT
GND
FB
C2
1μF
＊
VREF
INV
Fig.7
ON/OFF
H:OFF
L:ON
●Selecting application components
(1) Output inductor
It is recommended to use an inductor which satisfies the following rating current (the following value of current), and also
has low DCR. The shield type inductor is preferable.
I peak = Io･(Vo/VIN) / η + VIN･(VOUT-VIN) / (2･VOUT･L･f) [A]
[ Io : Output Vo : Output voltage VIN : Input voltage η : Efficiency L : Inductance f : Oscillating frequency ]
(2) Output capacitor
It is recommended to use the output capacitor which has the enough margin to maximum rating for output voltage and
low fluctuation for temperature. The ripple voltage of the output is influenced by ESR of the output capacitor.
Vripple = VINï½¥(VOUT-VIN) / (VOUTï½¥Lï½¥f)ï½¥ESR [V]
(f >> 1 / (2π√LC)･Vo / VIN)
[ Io : Output Vo : Output voltage VIN : Input voltage η : Efficiency L : Inductance C : Output capacitor
f : Oscillating frequency ]
(3) FET
It is recommended to use FETs which satisfy followings and have small Ciss or Qg and ON resistance.
D-S Voltage : Over (Output voltage + Vf of Di)
G-S Voltage : Over input voltage
D-S Current : Over Ipeak at the section of output inductor
(4) Diode
It is recommended to use a schottky diode which satisfies followings and has low forward voltage drop and high switching
speed.
Maximum current : Over maximum output current
Direct reverse voltage : Over output voltage
* Please provide sufficient margin in the choice of external components by factoring into the worst case characteristics and temperature range.
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5/11
2009.05 - Rev.A