ADP2164

Data Sheet

Rev. 0 | Page 16 of 20

APPLICATIONS INFORMATION

The typical application circuit for the ADP2164 is shown in

Figure 38.

ADP2164ACPZ

47µF

X5R

10V

47µF

X5R

6.3V

100µF

X5R

6.3V

1.2V

4A

3.3V

SYNC

TRK

FB

RT

SW

SW

SW

PVIN

GND PGND PGND PGND

L

0.8µH

10kΩ

10kΩ

L: MSS1048-801NL COILCRAFT

12

11

10

9

4

3

2

1

56

7

8

PGOOD

C1

0.1µF

EN

R1

10Ω

R2

10kΩ

PVIN

16

15

VIN

14

13

Figure 38. Typical Application Circuit

OUTPUT VOLTAGE SELECTION

The output voltage of the adjustable version of the ADP2164 is

set by an external resistive voltage divider using the following

equation:

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

+

×

=

BOT

TOP

OUT

R

R

V

1

6

.

0

To limit output voltage accuracy degradation due to FB bias

current (0.1 μA maximum) to less than 0.5% (maximum),

INDUCTOR SELECTION

The inductor value is determined by the operating frequency,

input voltage, output voltage, and ripple current. A small inductor

value provides larger inductor current ripple and fast transient

response but degrades efficiency; a large inductor value provides

small inductor current ripple and good efficiency but slows

transient response. For a reasonable trade-off between transient

set to one-third the maximum load current. The inductor value

is calculated using the following equation:

(

)

S

L

OUT

IN

f

I

D

V

V

L

×

Δ

×

−

=

where:

is the input voltage.

is the output voltage.

is the inductor current ripple.

is the switching frequency.

D

The ADP2164 uses slope compensation in the current control

loop to prevent subharmonic oscillations when the duty cycle

is larger than 50%. The internal slope compensation limits the

minimum inductor value.

The negative current limit (−1.3 A) also limits the minimum

the selected inductor should not exceed 2.6 A.

The peak inductor current should be kept below the peak current

limit threshold and is calculated using the following equation:

2

L

O

PEAK

I

I

I

Δ

+

=

Ensure that the rms current of the selected inductor is greater

than the maximum load current and that its saturation current

is greater than the peak current limit of the converter.

OUTPUT CAPACITOR SELECTION

The output capacitor value is determined by the output voltage

ripple, load step transient, and loop stability. The output ripple

is determined by the ESR and the capacitance.

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

×

×

+

×

Δ

=

Δ

S

OUT

L

OUT

f

C

ESR

I

V

8

1

The load step transient response depends on the inductor, the

output capacitor, and the current control loop.

The ADP2164 has integrated loop compensation for simple

power design. Table 5 and Table 6 show the recommended

values for inductors and capacitors for the ADP2164 based

on the input and output voltages for the part. X5R or X7R

dielectric ceramic capacitors are highly recommended.

L (μH)

3.3

1.0

0.8

100 + 100

3.3

1.2

0.8

100 + 47

3.3

1.5

1

100 + 47

3.3

1.8

1

100

3.3

2.5

1

47

5

1.0

0.8

100 + 100

5

1.2

0.8

100 + 47

5

1.5

1

100 + 47

5

1.8

1

100

5

2.5

1

47

5

3.3

1

47