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EN5339QI

3A PowerSoC Low Profile Synchronous Buck DC-DC Converter with Integrated Inductor

Altera Corporation 

EN5339QI

Application Information

Setting the Output Voltage

The EN5339 uses a simple and flexible resistor

divider network to program the output voltage. A

feed-forward capacitor (Ca) is used to improve

transient response. Table 3 shows the

recommended component values for the feedback

network as a function of VOUT. It is recommended

to use 1% or better feedback resistors to ensure

output voltage accuracy. The Ra resistor value is

fixed at 348k as shown in Table 3. Based on that

value, the bottom resistor Rb can be calculated

below as:

Rb = Ra× 0.6 V

VOUT − 0.6 V

The VOUT is the nominal output voltage. The Rb

and Ra resistors have the same units based on the

above equation.

VIN

CIN

22µF

1µF

100k

ENABLE POK VOUT

PVIN

TST0

TST1

EN5339QI

Ca

TST2

PGND

VFB

AVIN AGND PGND

POK

Ra

Rb

VOUT

COUT

3x 22µF

or

2x 47µF

Figure 6. Typical Application Circuit.

(NOTE: Enable can be separated from PVIN if the

application requires it)

capacitors. Y5V or equivalent dielectrics lose too

much capacitance with frequency, DC bias, and

temperature. Therefore, they are not suitable for

switch-mode DC-DC converter filtering, and must

be avoided.

Table 1: Recommended Input Capacitors

Description

22µF, 10V,

X5R, 0805

MFG

Taiyo

Yuden

Murata

P/N

LMK212BBJ226MG-T

GRM21BR61A226ME51

Output Filter Capacitor Selection

The EN5339QI output capacitor selection may be

determined based on two configurations. Table 3

provides the recommended output capacitor

configurations based on operating conditions. For

lower output ripple, choose 3 x 22µF for the output

capacitors. For smaller solution size, use two 47µF

output capacitors. Table 2 shows the

recommended type and brand of output capacitors

to use. For details regarding other configurations,

contact

Power

Applications

Support

(www.altera.com/mysupport).

Table 2: Recommended Output Capacitors

Description

47µF, 6.3V,

X5R, 0805

22µF, 10V,

X5R, 0805

MFG

Taiyo

Yuden

Murata

Taiyo

Yuden

Murata

P/N

JMK212BBJ476MG-T

GRM21BR60J476ME15

LMK212BBJ226MG-T

GRM21BR61A226ME51

AVIN Filter Capacitor

A 1.0 µF, 10V, 0402 MLCC capacitor should be

placed between AVIN and AGND as close to the

pins as possible. This will provide high frequency

bypass to ensure clean chip supply for optimal

performance.

Input Filter Capacitor Selection

A single 22µF, 0805 MLCC capacitor is needed on

PVIN for all applications. Connect the input

capacitor between PVIN and PGND as close to the

pins as possible. Placement of the input capacitor

is critical to ensure low conducted and radiated

EMI.

Low ESR MLCC capacitors with X5R or X7R or

equivalent dielectric should be used for the input

Table 3. Typical Recommended Components

(Note: Follow Layout Recommendations)

VIN (V) IOUT VOUT

COUT

Ra

Ca

(kΩ)

(pF)

0.9V

1V

1.2V

3x 22µF

(0805)

2.5

1.5V

to

3A

Or

5.5

1.8V

2.5

2x 47µF

(0805)

2.85V

10

348

8.2

3.3V

06903

June 26, 2015

www.altera.com/enpirion, Page 14

Rev E

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