AIC1653 데이터 시트보기 (PDF) - Analog Intergrations
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AIC1653 Datasheet PDF : 11 Pages
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AIC1653
Inductor Selection – Inverting Charge Pump
Regulator
This topology, inverting charge pump regulator, is
recommended when internal power switch voltage
is over its maximum rating.
As the inverting regulator application above, its
internal power switch voltage is 9.6V (the sum of
the absolute value of 3.6V input and –6V output),
which is fine as it is under the maximum rating, 30V.
However, any applications of internal power switch
voltage exceeding the maximum rating, topology of
inverting charge pump regulator is recommended
for their system.
For example, a 12V to -30V converter will generate
42V internal power switch voltage, which exceeds
its maximum rating 30V. For such a system, an
inverting charge pump regulator is the
recommended topology.
Appropriate inductor value for an inverting charge
pump regulator can be calculated by formula (2).
For designs with varying VIN value such as
battery-powered applications, minimum VIN value
is used in formula (2).
L=
VOUT
− VIN(MIN) + VD
ILIM
t OFF
(2)
Capacitor Selection
Output Capacitors
Low ESR (Equivalent Series Resistance)
capacitors should be used at output terminal to
minimize the output ripple voltage.
Multilayer ceramic capacitors are the best choice
as they have a very low ESR and are available in
low-profile packages. Due to the advantage of
small size, it makes multilayer ceramic capacitors
and AIC1653’s SOT-23 packages good
companions for size-concerning applications.
Solid tantalum capacitors are another alternative
for output capacitors, but they take more board
area and have larger ESR than ceramics.
Input Capacitors
Ceramic capacitors also make a good choice for
the input decoupling capacitor, which should be
placed as close as possible to AIC1653. A 4.7µF
input capacitor is sufficient for most applications.
Be aware that, sufficient voltage rating is required
for capacitor selection.
Diode Selection
For most AIC1653 applications, Rohm RB521S-30
surface mount Schottky diode (200mA, 30V)
providing the advantage of low forward voltage and
fast switching speed is an ideal choice. Note that,
generally, rating of handling minimum current at 1A
is required for AIC1653 applications.
Reducing Output Ripple Voltage
Using low ESR capacitors will help reduce the
output ripple voltage. In addition, proper selection
of the inductor and the output capacitor plays an
important role in output ripple voltage reduction.
The AIC1653 provides energy to the output in
8
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