AN93

11

11

 

 

 

 

 

 

 

 

 

 

 

 

 

C27

 

 

C26

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Y1

 

1

 

 

 

 

2

 

 

 

 

11

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8D

1

 

Traces, pad sites and vias

 

 

U1 Si24HS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

enclosed in box are in the DAA

 

 

 

 

3A

 

 

 

 

 

 

4C

 

 

 

 

5

 

 

section, and must be separated

 

1

XTALI

 

 

 

 

 

 

 

 

 

 

 

 

 

from all other circuits by 5 mm.

 

2

XTALO

 

 

C52 12

 

 

 

 

 

C7

 

 

 

 

 

 

 

 

C50

 

 

 

21

 

 

 

 

 

 

 

 

9C

 

Q5

 

 

 

 

 

 

VDD3.3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

12

5

20

 

 

 

 

 

 

 

4B

 

 

 

 

 

 

 

 

 

VDD3.3

GND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6

19

 

 

 

 

 

 

 

R9

 

 

 

 

 

 

 

 

GND

VDDB

C53

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7

VDDA

 

12

2

 

 

4A

 

3A

 

 

 

4D

 

8D

 

 

 

 

 

C51

 

 

R12*

C1

3B

+

 

 

 

R2

 

 

 

 

 

 

12

 

C1A

14

 

C4

 

1

QE

DCT2

16

6

 

 

 

 

 

 

 

13

3C

3E C2

 

 

 

2

15

 

Q4

 

 

 

 

 

 

 

C1B

 

 

 

DCT

IGND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3

RX

DCT3

14

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4

IB

QB

13

 

 

 

 

 

 

 

 

 

 

 

 

 

R13*

 

 

 

 

 

5

C1B

QE2

12

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6

11

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C2B

SC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

7

10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VREG

VREG2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8

9

 

 

 

 

 

 

 

 

 

*Note: Do

NOT

use ferrite

 

 

 

 

RNG1

RNG2

 

 

 

 

 

 

 

 

 

 

 

C5

 

3E

3E

 

C6

 

 

 

 

 

 

 

beads in place of R12 and

 

 

4G

 

 

R7

 

9B

4F

 

4E

 

 

 

 

 

 

 

R13.

 

 

 

 

 

 

 

 

4F

U2

Si3018

R8

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9C

 

 

 

 

 

 

 

9C

 

C3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3E

 

8C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10

 

 

 

 

 

 

RING

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

D1

FB2

 

R16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-

+

 

 

7A

RV1

 

 

 

 

 

 

 

 

 

 

 

3E

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TIP

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FB1

 

R15

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C9

C8

 

 

 

 

 

 

 

 

 

 

 

7B

 

 

 

 

 

 

 

7B

7C

7C

7B

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

2

 

Note: Encircled references are described in the numbered paragraphs in Appendix A.

This is not a complete schematic. Only critical component placement and nets are drawn.

Figure 21. Illustrated Layout Guidelines

4.4.1. ISOmodem Layout Check List

Table 34 is a checklist that the designer can use during the layout process to ensure that all the recommendations in this application note have been implemented. Additionally, Figure 21 provides an annotated diagram of all relevant layout guidelines for the SI3054 CNR/AMR/ACR applications. See "10.4.2. Safety" on page 254 for information about design for safety compliance.

Table 34. Layout Checklist

 

P

#

Layout Items

Required

 

 

 

 

 

 

 

 

1

U1 and U2 are placed so that pins 9–16 of U1 are facing pins 1–8 of U2. C1 and C2

 

 

 

 

 

are placed directly between U1 and U2.

 

 

 

 

 

 

 

 

 

 

2

Place U1, U2, C1, and C2 so that the recommended minimum creepage spacing for

 

 

 

 

 

the target application is implemented. R12 and R13 should be close to U1.

 

 

 

 

 

 

 

 

 

 

3

C1 and C2 should be placed directly between U1 and U2. Short, direct traces should

 

 

 

 

 

be used to connect C1 and C2 to U1 and U2. These traces should not be longer than

 

 

 

 

 

two inches and should be minimized in length. Place C2 such that its accompanying

 

 

 

 

 

trace to the C2B pin (pin 6) on the Si3018 is not close to the trace from R7 to the

 

 

 

 

 

RNG1 pin on the Si3018 (pin 8).

 

 

 

 

 

 

 

 

 

 

4

Place R7 and R8 as close as possible to the RNG1 and RNG2 pins (pins 8 and 9),

 

 

 

 

 

ensuring a minimum trace length from the RNG1 or RNG2 pin to the R7 or R8 resistor.

 

 

 

 

 

In order to space the R7 component further from the trace from C2 to the C2B pin, it is

 

 

 

 

 

acceptable to orient it 90 degrees relative to the RNG1 pin (pin 8).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rev. 1.3

51

Page 51
Image 51
Silicon Laboratories SI2494/39, SI2493/57/34/15/04 Layout Checklist, ISOmodem Layout Check List, Layout Items Required