AIC1639 查看數據表（PDF） - Analog Intergrations
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AIC1639 Datasheet PDF : 11 Pages
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Valley current (Iv) is
IV
=
Vout + Vd − Vsw
Vin − Vsw
−
x
2
Iout
−
Vin
− Vsw
2L
Ton
1−
x
2
AIC1639
3-PIN ONE-CELL STEP-UP DC/DC CONVERTER
SPEC NO: DS-1639-00 05/26/00
Table 1 Indicates resistance and height for each coil.
Power Inductor Type
Inductance ( µH )
Sumida SMT Type CD54
47
100
Hold SMT Type PM54
47
100
Hold SMT Type PM75
33
Huan Feng PIN Type V0810
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 unacceptably
poor ESR and ESL. There are low ESR aluminum ca-
pacitors for switch mode DC-DC converters which work
much better than general porpuse unit. Tantalum ca-
pacitors provide still better performance at more expen-
sive. 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 volt-
age.
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 diode
such 1N5819. Motorola makes MBR0530 in surface
mount. For lower output power a 1N4148 can be used
although efficiency and start-up voltage will suffer sub-
stantially.
COMPONENT POWER DISSIPATION
Opeating in discontinuous mode, power loss in the
winding resistance of inductor can be approximate
equal to
PDL
=
2
3
Ton
L
(Rs
)
Vout + Vd
Vout
(Pout
)
where Pout=Vout * Iout ; Rs=Inductor DC R;
VD = Diode drop.
The power dissipated in a switch loss is
PDsw
=
2
3
ToLn
(Ron )Vout
+ Vd
Vout
− Vin
(Pout
)
The power dissipated in rectifier diode is
PDd
=
Vd
Vout
(Pout )
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
10
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