ISL40 Datasheet, PDF (10/12 Pages) Yamar Electronics Ltd. – Independent DC-LIN Slave For Asynchronous Communication Over Noisy Lines

Proprietary and Confidential Information of YAMAR Electronics Ltd.
4.5 Ceramic Filter
The ISL40 is designed to operate with one ceramic filter for transmission and reception. However, if
switching between two channels is desired, two ceramic filters are required. The minimum allowable
bandwidth of the ceramic filters is +/-70 kHz @ 3dB. Narrower bandwidth limits the maximal bit rate.
The ISL40 selectable frequencies are designed according to the market available ceramic filters.
Nominal 3 db BW 20db Insertion Stop band In/Out
Murata
freq.
BW
loss
attenuation imped.
part #
MHz
KHz KHz
dB
dB
Ohm
min. max.
max.
min.
*3.58
+/-40 530 6.0
25
530
SFSH3.58MCB
4.5
+/-70 750 6.0
30
1000
SFSL4.5MDB
5.5
+/-80 750 6.0
30
600
SFSL5.5MDB
6.0
+/-80 750 6.0
30
470
SFSL6.0MDB
6.5
+/-80 800 6.0
30
470
SFSL6.5MDB
• The 3.58MHz frequency can be operated with 9.6Kbps and 19.2Kbps only
Oscilent
part #
773-0045
773-0055
773-0060
773-0065
4.6 Oscillator
The ISL40 is designed to operate with a low cost 32.768KHz crystal connected between OscIn and
OscOut pins. This type of crystal has the advantage of very low power consumption and low cost.
However there are also drawbacks. It is very sensitive to noise and has a temperature dependency that
should be carefully considered when selecting the crystal.
The following guidelines should be used when designing the PCB:
1. Design the trace length as short as possible.
2. Avoid thin line on resonator traces (< 0.010"), keep them as wide as possible.
3. To avoid noise, protect these signals with Ground shields.
The exact values of C1, C2, R1 and R2 should be determined according to the crystal manufacturer.
4.7 Recommended 32.768KHz Crystal Specifications
Type
Nominal Frequency:
Frequency tolerance @25ºC
Load capacitance
Serial resistance
Drive level
Quality factor
Turnover temperature
Parabolic constant
Aging
Operating temperature
Storage temperature
Value
32.768KHz
+/-20 ppm
12.5 pF
50K Ohm (max.)
1uW (max.)
50,000 (max.)
+25ºC +/- 5ºC
-0.04 ppm/ºC² (max.)
+/-3 ppm in first year (max.)
-40ºC to + 85ºC
-55ºC to + 125ºC
The overall frequency tolerance should not exceed 200ppm.
4.8 Communication performance
The maximal cable length between extreme 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 SIG40 needs at least 20mVpp for proper reception. Good communication should be achieved if an
oscilloscope at the SIG40 receiver can see the transmitted signal within the noise.
© 2007 Yamar Electronics Ltd.
10
DS-ISL40 R1.6