RT9209A Ver la hoja de datos (PDF) - Richtek Technology
Número de pieza
componentes Descripción
Fabricante
RT9209A Datasheet PDF : 14 Pages
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COUNT = 1
4V
2V
0V
COUNT = 2 COUNT = 3
OVERLOAD
APPLIED
0A
T0 T1
T2
T3
TIME
Figure 3
Inductor Selection
The RT9209/A was designed for VIN = 5V, step-down
application mainly. Figure 4 shows the typical topology
and waveforms of step-down converter.
The ripple currents of inductor can be calculated as follows:
(5V - VOUT)
ILRIPPLE =
× TON
L
Because operation frequency is fixed at 260kHz/400kHz,
VOUT
VOUT
TON = 3.85 ×
, or 2.5 ×
5V
5V
The VOUT ripple is
VOUT RIPPLE = ILRIPPLE × ESR
ESR is output capacitor equivalent series resistor
RT9209/A
L
Q
VI
D
C
R VO
C.C.M.
TS
VL
iL
TON TOFF
VI - VO
- VO
uQ
uIL
IL = IO
iQ
IQ
iD
ID
Figure 4
DS9209/A-08 March 2007
www.richtek.com
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