R1224N122G RICOH [RICOH electronics devices division], R1224N122G Datasheet - Page 12

• Manufacturer Part Number: R1224N122G
• Description: PWM/VFM step-down DC/DC Converter
• Manufacturer: RICOH [RICOH electronics devices division]

12
External Components
1.
2.
3.
4.
R1224N
Inductor
Select an inductor that peak current does not exceed ILmax. If larger current than allowable current flows,
magnetic saturation occurs and make transform efficiency worse.
When the load current is definite, the smaller value of L, the larger the ripple current.
Provided that the allowable current is large in that case and DC current is small, therefore, for large output
current, efficiency is better than using an inductor with a large value of L and vice versa.
Diode
Use a diode with low V
Reverse voltage rating should be more than V
Capacitors
As for C
stable operation.
C
recommended.
Lx Transistor
Pch Power MOSFET is required for this IC.
Its breakdown voltage between gate and source should be a few V higher than Input Voltage.
In the case of Input Voltage is low, to turn on MOSFET completely, to use a MOSFET with low threshold
voltage is effective.
If a large load current is necessary for your application and important, choose a MOSFET with low ON
resistance for good efficiency.
If a small load current is mainly necessary for your application, choose a MOSFET with low gate capacity for
good efficiency.
Maximum continuous drain current of MOSFET should be larger than peak current, ILmax.
OUT
can reduce ripple of Output Voltage, therefore 47µF or more value of tantalum type capacitor is
IN
, use a capacitor with low ESR (Equivalent Series Resistance) and a capacity of at least 10µF for
F
(Schottky type is recommended.) and high switching speed.
IN
and current rating should be equal or more than ILmax.