bd9763fvm ROHM Co. Ltd., bd9763fvm Datasheet - Page 6

• Manufacturer Part Number: bd9763fvm
• Description: Single-output Step-up, High-efficiency Switching Regulators Controller Type
• Manufacturer: ROHM Co. Ltd.

●Selecting application components
(1) Output inductor
(2) Output capacitor
(3) FET
(4) Diode
(5) Setting the oscillator frequency
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.
[ Io : Output Vo : Output voltage VIN : Input voltage η : Efficiency L : Inductance f : Oscillating frequency ]
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.
[ Io : Output Vo : Output voltage VIN : Input voltage η : Efficiency L : Inductance
It is recommended to use FETs which satisfy followings and have small Ciss or Qg and ON resistance.
It is recommended to use a schottky diode which satisfies followings and has low forward voltage drop and high switching
speed.
Refer to Fig.5 and determine Timing resistor (RRT) when setting the oscillating frequency.
I peak = Io･(Vo/VIN) / η + VIN･(VOUT-VIN) / (2･VOUT･L･f) [A]
Vripple = VIN･(VOUT-VIN) / (VOUT･L･f)･ESR [V]
(f >> 1 / (2π√LC)･Vo / VIN)
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
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.
10000
1000
100
Fig.5 Oscillating frequency – Timing resistance (R
1
Oscillating frequency vs. Timing resistance
Timing resistance (RT) [kΩ]
10
Fig.7
6/12
100
C : Output capacitor f : Oscillating frequency ]
RT
)
1000