Preliminary and proprietary Information of YAMAR Electronics Ltd. Subject to change without notice.

© 2010 Yamar Electronics Ltd.

7

DS-SIG61 R0.932

3.2 Ceramic Filter

The SIG61 can operate with a single ceramic filter for transmission and reception. If, however,

switching between two channels is desired, two ceramic filters will be required. The minimum allowable

3dB bandwidth of the ceramic filters is ±70 kHz. Choosing a narrower bandwidth shall limit the

maximum achievable bit rate.

The SIG61 selectable carrier frequencies are chosen in accordance with ceramic filter values available

in the market.

Nominal

freq.

[MHz]

3 dB BW

[KHz]

20dB

BW

[KHz]

Insertion

loss

[dB]

Stop band

attenuation

[dB]

In/Out

imped.

[ ]

Murata

part #

Oscilent

part #

*1.75

Discrete

4.50

±70

750

6.0

30

1000

SFSL4.5MDB

773-0045

5.50

±80

750

6.0

30

600

SFSL5.5MDB

773-0055

6.00

±80

750

6.0

30

470

SFSL6.0MDB

773-0060

6.50

±80

800

6.0

30

470

SFSL6.5MDB

773-0065

**10.50

±150

4.5

330

SFELF10M5JAA001-B0

Discrete filter for 115.2Kbps

**13.00

±280

4.5

330

SFELK13M0JA00-B0

*1.75

Discrete

* 1.75MHz can operate only at 9.6Kbps

** 10.5MHz and 13.00MHz can operate at 115.2Kbps instead of 9.6Kbps.

3.3

Oscillator

The SIG61 is designed to operate with a low cost 4MHz crystal connected between OscIn and

OscOut pins. Each of these pins should be connected to the ground via a capacitor. All the

corresponding PCB traces should be as short as possible.

Recommended crystals are:

1.

NDK AT-51 GW.

2.

Epson MA-506.

The values of C1, and C2 in Figure 3.3, pertaining to the oscillator circuitry, should be determined

according to the crystal manufacturer recommendations. Values between 0pF and 4.7pF may serve as

good starting point.

The overall frequency tolerance should not exceed 200ppm.

3.4

Communication performance

The maximum cable length between two devices depends mainly on the AC impedance of loads

connected to that line and number of nodes. The DC cable length has less effect on communication.

The SIG61 requires a minimum received signal of 20mVpp for proper reception.