ADP1614

Data Sheet

Rev. 0 | Page 12 of 16

APPLICATIONS INFORMATION

ADIsimPower DESIGN TOOL

The ADP1614 is supported by the ADIsimPower™ design toolset.

ADIsimPower is a collection of tools that produce complete

power designs that are optimized for a specific design goal. The

tools enable the user to generate a full schematic and bill of

materials and to calculate performance in minutes. ADIsimPower

can optimize designs for cost, area, efficiency, and parts count

while taking into consideration the operating conditions and

limitations of the IC and the external components. For more

information about the ADIsimPower design tools, visit

www.analog.com/ADIsimPower. The toolset is available from

this website, and users can request an unpopulated board.

SETTING THE OUTPUT VOLTAGE

to 20 V. The output voltage is set by the resistor voltage divider,

1.245 V feedback input at FB. Use the following equation to

determine the output voltage:

(1)

Choose R1 based on the following equation:













−

×

=

245

.

1

245

.

1

OUT

V

R2

R1

(2)

INDUCTOR SELECTION

The inductor is an essential part of the step-up switching

converter. It stores energy during the on time of the power

switch and transfers that energy to the output through the

output rectifier during the off time. To balance the trade-offs

between small inductor current ripple and efficiency, induc-

tance values in the range of 4.7 µH to 22 µH are recommended.

In general, lower inductance values have higher saturation

current and lower series resistance for a given physical size.

However, lower inductance values result in higher peak current,

which can lead to reduced efficiency and greater input and/or

output ripple and noise. A peak-to-peak inductor ripple current

close to 30% of the maximum dc input current typically yields

an optimal compromise.

For determining the inductor ripple current in continuous

the switch duty cycle (D) as follows:

OUT

IN

OUT

V

V

V

D

−

=

(3)

determine the on time:

SW

ON

f

D

t

=

(4)

L

t

V

I

ON

IN

L

×

=

∆

(5)

Solve for the inductance value (L) as follows:

L

ON

IN

I

t

V

L

∆

×

=

(6)

Ensure that the peak inductor current (the maximum input

current plus half the inductor ripple current) is below the rated

saturation current of the inductor. Likewise, make sure that the

maximum rated rms current of the inductor is greater than the

maximum dc input current to the regulator.

For continuous current-mode (CCM) duty cycles greater than

50% that occur with input voltages less than one-half the output

voltage, slope compensation is required to maintain stability of

the current-mode regulator. For stable current-mode operation,

ensure that the selected inductance is equal to or greater than

parameters in the following equation:

SW

IN

OUT

MIN

f

V

V

L

L

×

×

−

=

>

8

)

2

(

(7)

Inductors smaller than the 4.7 µH to 22 µH recommended

range can be used as long as Equation 7 is satisfied for the given

application. For input/output combinations that approach the

90% maximum duty cycle, doubling the inductor is recom-

mended to ensure stable operation. Table 5 suggests a series

of inductors for use with the ADP1614.

Table 5. Suggested Inductors

Manufacturer

Part Series

Coilcraft

XAL40xx, XAL50xx, XAL6060, DO3316P

TOKO Inc.

FDV06xx, DG6045C, FDSD0630, DEM8045C,

FDVE1040

Würth Elektronik

WE-HCI, WE-TPC, WE-PD, WE-PD2, WE -PDF

Vishay Dale

IHLP-2020, IHLP-2525, IHLP-3232, IHLP-4040

TDK Components

SPM6530, VLP8040, VLF10040, VLF10045

Taiyo Yuden

NRS8030, NRS8040