IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 1

USER GUIDE FOR IR3448 EVALUATION BOARD

DESCRIPTION

The IR3448 is a synchronous buckconverter, providing a compact, highperformance and flexible solution in a small5mmx6mm QFN package.

Key features offered by the IR3448 includeinternal Digital Soft Start, precision 0.6Vreference voltage, Power Good, thermalprotection, programmable switchingfrequency, Enable input, input under-voltagelockout for proper start-up, enhanced line/load regulation with feed forward, externalfrequency synchronization with smoothclocking, internal LDO, true differentialremote sensing and pre-bias start-up.

A thermally compensated output over-currentprotection function is implemented by sensingthe voltage developed across the on-resistanceof the synchronous rectifier MOSFET foroptimum cost and performance.

This user guide contains the schematic and billof materials for the IR3448 evaluation board.The guide describes operation and use of theevaluation board itself. Detailed applicationinformation for IR3448 is available in theIR3448 data sheet.

BOARD FEATURES

• Vin = +12V

• Vout = +0.9V @ 0-16A

• Fs = 1MHz

• L = 0.16uH

• Cin = 2x22uF (ceramic 1206) + 1x330uF* (electrolytic)

• Cout = 6x47uF (ceramic 0805)

* The 330uF input capacitor is placed for damping the parasitic inductance of bench power supply wires. It is not required for the POL applications where input is delivered with power planes.

SupIRBuckTM

IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 2

A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum of 16A load shouldbe connected to VOUT+ and VOUT-. The inputs and output connections of the board are listed in Table I.

IR3448 needs only one input supply and internal LDO generates Vcc from Vin. The board is configured forremote sensing.

External Enable signal can be applied to the board via exposed Enable pad and R18 should be removed forthis purpose.

CONNECTIONS and OPERATING INSTRUCTIONS

LAYOUTThe PCB is a 6-layer board. All of layers are 2 Oz. copper. The IR3448 and most of the passivecomponents are mounted on the top side of the board.

Power supply decoupling capacitors and feedback components are located close to IR3448. Thefeedback resistors are connected to the output of the remote sense amplifier of the IR3448 and arelocated close to the IR3448. To improve efficiency, the circuit board is designed to minimize the length

of the on-board power ground current path. Separate power ground and analog ground are used andmay be connected together using a single point connection.

Table I. Connections

Connection Signal Name

VIN+ Vin (+12V)

VIN- Ground of Vin

Vout+ Vout(+0.9V)

Vout- Ground for Vout

Vcc+ Vcc Pin

Vcc- Ground for Vcc input

Enable Enable

PGood Power Good Signal

AGnd Analog ground

IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 3

CONNECTIONS and OPERATING INSTRUCTIONS

LAYOUTThe PCB is a 6-layer board. All of layers are 2 Oz. copper. The IR3448 and most of the passivecomponents are mounted on the top side of the board.

Power supply decoupling capacitors and feedback components are located close to IR3448. Thefeedback resistors are connected to the output of the remote sense amplifier of the IR3448 and arelocated close to the IR3448. To improve efficiency, the circuit board is designed to minimize the length of

the on-board power ground current path.

Vin

Vo

Gnd

Gnd

Top View

IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 4

Fig

.1:

Sch

emat

ico

fth

eIR

3448

eval

uat

ion

bo

ard

C1

9

47uF

C20

47u

F

14

0.1

uF

PG

D

L1

160nH

Vou

t+123456

Cb

yp

C25

0.1

uF

Vo_

R_P

Vo

ut

C2

6

4.7n

F

Vo_

R_N

R1

97

.5k

C66

10u

F

R1

1.8k

C3

22u

F

BO

DE

JUM

PE

R 2

R4

47.

5

R2

2.67

k

R6

20

R3

5.3

6k

C8

22

00pF

Fb

C3

91u

F

PV

inR

18

49

.9k

+C

1

330

uF

U1

IR3

448

Vin17

LGnd11

Rt/

Sy

nc

4

SW

22

Vc

c1

8C

omp

8

Vs

ns

6

PG

nd

26

OC

Se

lect

5

FB

7B

oo

t2

PG

D1

6

PVin1

PGnd10

RS-12R

S+

13

RS

o9

SW

21

SW

23

SW

20

SW

24

SW

32

Cbyp14NC5

15

Enable3

PGnd27

PGnd29

SW

25

NC

12

8

NC

23

0

NC

33

1

NC

43

3

NC

01

9

R9

23.2

k

C2

22u

F

Vo

ut

C15

47u

F

C1

6

47uF

Rt/

Sy

nc

VC

C

Vo

ut-

123456

C11

75p

F

PI

N1

1P

IN

10

C1

0

100

pF

R17

10k

C3

7

0.1u

F

C17

47u

F

C18

47u

F

Vin

+

123456

Vin

-

123456

IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 5

Bill of Materials

Item Qty Part Reference Value Description Manufacturer Part Number

1 1 C1 330uFSMD Elecrolytic, Fsize,

25V, 20%Panasonic EEE-FK1E331P

2 2 C2 C3 22uF 1206, 25V, X5R, 10% Murata GRM31CR61E226KE15L

3 1 C10 100pF 0402, 50V, NP0, 5% Murata GRM1555C1H101JZ01D4 3 C14 C25 C37 0.1uF 0402, 50V, X7R, 10% TDK C1005X7R1H104K050BB5 1 C8 2200pF 0402, 25V, NP0, 5% Kemet C0402C222J3GACTU6 1 C11 75pF 0402, 50V, NP0, 5% Murata GRM1555C1H750JA01D

7 6C15 C16 C17C18 C19 C20

47uF 0805, 6.3V, X5R, 20% TDK C2012X5R0J476M

8 1 C26 4.7nF 0402, 50V, X7R, 10% Murata GRM155R71H472KA01D9 1 C39 1uF 0402, 25V, X5R,10% TDK C1005X5R1E105K050BC

10 1 C66 10uF 0603, X5R, 10V, 20% TDK C1608X5R1A106M080AC11 1 L1 0.16uH 0.16uH, DCR=2.15mohm Coilcraft XAL5030-161ME_12 1 R1 1.8k 0402,1/10W,1% Panasonic ERJ-2RKF1801X13 1 R2 2.67k 0402,1/10W,1% Panasonic ERJ-2RKF2671X14 1 R3 5.36k 0402,1/10W,1% Panasonic ERJ-2RKF5361X15 1 R4 47.5 0402,1/10W,1% Panasonic ERJ-2RKF47R5X16 1 R6 20 0402,1/10W,1% Panasonic ERJ-2RKF20R0X17 1 R9 23.2k 0402,1/10W,1% Panasonic ERJ-2RKF2322X18 1 R17 10k 0402,1/10W,1% Panasonic ERJ-2RKF1002X19 1 R18 49.9k 0402,1/10W,1% Panasonic ERJ-2RKF4992X20 1 R19 7.5k 0402,1/10W,1% Panasonic ERJ-2RKF7501X

21 1 U1 IR3448 IR3448 5mm X6mmInternational

RectifierIR3448MPBF

IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 6

TYPICAL OPERATING WAVEFORMSVin=12.0V, Vout=0.9V, Iout=0A-16A, Fs=1MHz, Room Temperature, No air flow

Fig. 5: Output Voltage Ripple, 16A load Ch2: Vout

Fig. 6: Inductor node at 16A loadCh1:SW Node

Fig. 7: Short (Hiccup) RecoveryCh2:Vout, Ch3:PGood, Ch4:Iout

Fig. 3: Start up at 16A Load Ch1:Vin, Ch2:Vout, Ch3:PGood,Ch4:Vcc

Fig. 2: Start up at 16A LoadCh1:Vin, Ch2:Vout, Ch3:PGood, Ch4:Enable

Fig. 4: Start up with 0.81V Pre Bias , 0A Load Ch2:Vout , Ch3:PGood, Ch4:Enable

IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 7

TYPICAL OPERATING WAVEFORMSVin=12.0V, Vout=0.9V, Iout=8A-16A, Fs=1MHz, Room Temperature, No air flow

Fig. 8: Transient Response, 8A to 16A step with Electronic load setting = 2.5A/us

Ch2:Vout, Ch4:Iout

IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 8

TYPICAL OPERATING WAVEFORMSVin=12.0V, Vout=0.9V, Iout=0A-16A, Fs=1MHz, Room Temperature, No air flow

Fig. 9: Bode Plot at 16A load shows: Fc = 185.6kHz, Phase Margin = 52.3º

IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 9

Fig.11: Power loss versus load current

Fig.10: Efficiency versus load current

TYPICAL OPERATING WAVEFORMSVin=12.0V, Vout=0.9V, Iout=0A-16A, Fs=1MHz, Room Temperature, No air flow

IRDC3448-P0V9

Confidential

This evaluation board is a preliminary version meant for the engineering evaluation of the IR3448. Based on the resultsof the continuing evaluation, this board can evolve and change without notice

AL

9/18/2013 10

THERMAL IMAGESVin=12.0V, Vout=0.9V, Iout=0A-16A, Fs=1MHz, Room Temperature, No air flow

Fig. 12: Thermal Image of the board top at 16A loadIR3448: 65.130C

Fig. 13: Thermal Image of the board bottom at 16A loadInductor: 69.290C