AIC1641 ETC [List of Unclassifed Manufacturers], AIC1641 Datasheet - Page 9

• Manufacturer Part Number: AIC1641
• Description: LOW VOLTAGE STEP-UP DC/DC CONVERTER
• Manufacturer: ETC [List of Unclassifed Manufacturers]

ANALOG INTEGRATIONS CORPORATION
4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C.
t the boundry between continuous and discontinuous
mode, output current (IOB) is determined by
I
where Vd is the diode drop,
x = (R
Ron= Switch turn on resistance, Rs= Inductor DC re-
sistance
T
In the discontinuous mode, the switching frequency
(fsw) is
In the continuous mode, the switching frequency is
fsw=
OB
F
ON
SW
=
= Switch ON time
T
=
V
I
V
ON
I
IN
SW
1
ON
V
EXT
SW
2(L)(V
I
OUT
+Rs)T
Continuous Conduction Mode
D
(V
V
V
IN
OUT
OUT
V
OUT
ON
V
D
IN
V
/L.
V
2
2
1
D
D
V
V
D
T
L
IN
V
V
ON
SW
T
IN
V
2
ON
IN
)
)(I
[1
1
OUT
I
PK
x
2
x
)
(
V
(1
OUT
V

x
IN
I
OUT
V
V
D
t
SW
V
SW
)]
Power required from the inductor per cycle must be
in order for the converter to regulate the output.
When loading is over IOB, PFM controller operates in
equal or greater than
P
continuous mode. Inductor peak current can be de-
rived from
LOW VOLTAGE STEP-UP DC/DC CONVERTER
where Vsw = switch drop and proportion to output
current.
INDUCTOR SELECTION
To operate as an efficient energy transfer element,
the inductor must fulfill three requirement. First, the
inductance must be low enough for the inductor to
store adquate energy under the worst case condition
of minimum input voltage and switch ON time. Sec-
ond, the inductance must also be high enough so
maximum current rating of AIC1641 and inductor are
not exceed at the other worst case cindition of
maximum input voltage and ON time. Lastly, the in-
ductor must have sufficiently low DC resistance so
excessive power is not lost as heat in the windings.
But unfotrunately this is inversely related to physical
size.
age and output current must be established before
and incuctor can be selected.
In discontinuous mode operation, at the end of the
switch ON time, peak current and energy in the in-
ductor build according to
L
I
TEL: [phone] FAX:[phone]
Minimum and Maximum input voltage, output volt-
www.analog.com.tw
PK
/f
SW
where x=(R
1
2
R
L
V
(V
T
L
V
ON
1
ON
IN
L
OUT
V
IN
I
T
PK
IN
ON
Rs
V


T
V
OUT
ON
V
OUT
ON
D
1
1
(simple lossless equation),
+Rs)T
V
V
V
exp(
IN
D
x
2
D
)(I
V
OUT
ON
V
SPEC NO: DS-1641-00 05/04/00
SW
IN
R
/L
)(
ON
fsw
L
1
Rs
)
T
AIC1641
ON
)
9