AIC1641 Datasheet, PDF (10/12 Pages) List of Unclassifed Manufacturers – LOW VOLTAGE STEP-UP DC/DC CONVERTER

IPK
=


VOUT + VD − VSW
VIN − VSW
−
x
2
IOUT

+


VIN − VSW
2L
TON1−

x
2


Valley current (Iv) is
AIC1641
LOW VOLTAGE STEP-UP DC/DC CONVERTER
SPEC NO: DS-1641-00 05/04/00
IV
=


VOUT + VD − VSW
VIN − VSW
−
x
2
IOUT

−


VIN
− VSW
2L
TON1−

x
2


Table 1 Indicates resistance and height for each coil.
Power Inductor Type
Sumida SMT Type CD54
Hold SMT Type PM54
Hold SMT Type PM75
Huan Feng PIN Type V0810
Inductance ( µH )
47
100
47
100
33
33
Resistance ( Ω )
0.25
0.50
0.25
0.50
0.11
40m
Rated Current (A)
0.7
0.5
0.7
0.5
1.2
2
Hieght
(mm)
4.5
4.5
5.0
10.0
CAPACITOR SELECTION
A poor choice for a output capacitor can result in poor
efficiency and hight output ripple. Ordinary aluminum
electrolytics, while inexpensive may have unaccepta-
bly poor ESR and ESL. There are low ESR aluminum
capacitors for switch mode DC-DC converters which
work much better than general porpuse unit. Tantalum
capacitors provide still better performance at more ex-
pensive. OS-CON capacitors have extremely low ESR
in a small size. If capacitance is reduced, output ripple
will increase.
Most of the input supply is supplied by the input by-
passs capacitor, the capacitor voltage rating should be
at least 1.25 times greather than a maximum input
voltage.
DIODE SELECTION
Speed, forward drop, and leakage current are the
three main consideration in selecting a rectifier diode.
Best performance is obtained with Schottky retifier di-
ode such 1N5819. Motorola makes MBR0530 in sur-
face mount. For lower output power a 1N4148 can be
used although efficiency and start-up voltage will suf-
fer substantially.
COMPONENT POWER DISSIPATION
Opeating in discontinuous mode, power loss in the
winding resistance of inductor can be approximate
equal to
PD_L
=
2 _ TON _{(Rs)}
3_ L _{ }
( ) ^{VOUT + VD}  POUT
VOUT _
where P_OUT=V_OUT * I_OUT ; Rs=Inductor DC R;
V_D = Diode drop.
The power dissipated in a switch loss is
PDsw = ²  ^TON (RON) ^{VOUT + VD − VIN} (POUT)
3_ L _

VOUT

The power dissipated in rectifier diode is
PDd =  ^VD (POUT)
 ^VOUT 
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