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 2006 Semtech Corp.

www.semtech.com

SC4602A/B

POWER MANAGEMENT

Applications Information (Cont.)

Layout Guideline

In order to achieve optimal electrical, thermal and noise

performance for high frequency converters, special at-

tention must be paid to the PCB layouts. The goal of lay-

out optimization is to identify the high di/dt loops and

minimize them. The following guideline should be used to

ensure proper functions of the converters.

1. A ground plane is recommended to minimize noises

and copper losses, and maximize heat dissipation.

2. Start the PCB layout by placing the power compo-

nents first. Arrange the power circuit to achieve a

clean power flow route. Put all the connections on

one side of the PCB with wide copper filled areas if

possible.

3. The Vcc bypass capacitor should be placed next to

the Vcc and GND pins.

4. The trace connecting the feedback resistors to the

output should be short, direct and far away from the

noise sources such as the phase node and switching

components.

5. Minimize the traces between PDRV/NDRV and the

gates of the MOSFETs to reduce their impedance to

drive the MOSFETs.

6. Minimize the loop including input capacitors, top/bot-

tom MOSFETs. This loop passes high di/dt current.

Make sure the trace width is wide enough to reduce

copper losses in this loop.

7. The PHASE connection to P-MOSFET for current sens-

ing must use Kelvin connection.

8. Maximize the trace width of the loop connecting the

inductor, bottom MOSFET and the output capacitors.

9. Connect the ground of the feedback divider and the

compensation components directly to the GND pin

of the SC4602A/B by using a separate ground trace.

Then connect this pin to the ground of the output

capacitor as close as possible.

A Design Example: 3.3V to1.5V @6A application with SC4602B (NH020 footprint)

R2

3.32K

C2

6.8n

R1

5.11k

C7

150u

C1

470p

R6

1.0

R5

1.0

L1

1.6u

C4

22u

M2

C10

22u

C11

22u

C12

22u

C13

22u

Vin = 3.3V

C9

3.3n

R8

169

R7

4.64k

R9

5.36k

R10

100

Vo = 1.5V/6A

U1

SC4602B

VCC

1

SY NC/SLEEP

2

COMP

3

VSENSE

4

PHASE

5

GND

6

NDRV

7

PDRV

8

J2

1

2

3

4

5

C3

4.7u

J1

1

2

3

4

5

6

GND

ON/OFF

TRIM

R11

100

ON/OFF

M1

R15

1

R2

3.32K

C2

6.8n

R1

5.11k

C7

150u

C1

470p

R6

1.0

R5

1.0

L1

1.6u

C4

22u

M2

C10

22u

C11

22u

C12

22u

C13

22u

Vin = 3.3V

C9

3.3n

R8

169

R7

4.64k

R9

5.36k

R10

100

Vo = 1.5V/6A

U1

SC4602B

VCC

1

SY NC/SLEEP

2

COMP

3

VSENSE

4

PHASE

5

GND

6

NDRV

7

PDRV

8

J2

1

2

3

4

5

C3

4.7u

J1

1

2

3

4

5

6

GND

ON/OFF

TRIM

R11

100

ON/OFF

M1

R15

1