21

 2004 Semtech Corp.

www.semtech.com

SC1486A

POWER MANAGEMENT

Application Information (Cont.)

Layout Guidelines (Cont.)

Next, looking at the power section, the schematics in Figures 10 and 11 below show the power sections for

VDDQ and VTT:

+

C13

330u/25m

Q2

IRF7811AV

1

2

3

4

5

6

7

8

S

S

S

G

D

D

D

D

1210

Q3

FDS6676S

1

2

3

4

5

6

7

8

S

S

S

G

D

D

D

D

0402

0402

1210

+

C14

330u/25m

7343

L1

2u4

7343

C2

0u1/25V

0603

C1

2n2/50V

C3

10u/25V

0402

C4

10u/25V

C12

0u1

1.8V, 10A

R7

0R

0402

R8

0R

L2

3u9

1210

0603

C6

0u1/25V

0603

0402

C7

2n2/50V

C5

10u/25V

C16

0u1

+

C15

220u/25m

0402

7343

0.9V, 1.5A

Q1

FDS6982S

4

1

2

3

5

6

7

8

Figure 10: VDDQ Power Section

Figure 11: VTT Power Section

The highest di/dts occur in the input loops (see Figures 12 and 13 below) and thus these should be kept as small

as possible.

Figure 12: VDDQ Input Loop

Figure 13: VTT Input Loop

C3

10u/25V

0603

C1

2n2/50V

1210

Q2

IRF7811AV

1

2

3

4

5

6

7

8

S

S

S

G

D

D

D

D

C2

0u1/25V

C4

10u/25V

0402

Q3 FDS6676S

1

2

3

4

5

6

7

8

S

S

S

GD

D

D

D

1210

0402

C6

0u1/25V

0603

C7

2n2/50V

Q1

FDS6982S

4

1

2

3

5

6

7

8

C5

10u/25V

1210

The input capacitors should be placed with the highest frequency capacitors closest to the loop to reduce EMI. Use

large copper pours to minimize losses and parasitics. See Figures 14 and 15 below for examples.

Figure 14: VDDQ Power Component Placement

And Copper Pours

Figure 15: VTT Power Component Placement

And Copper Pours