Datasheet
Table Of Contents
ADM3053 Data Sheet
Rev. E | Page 16 of 18
R
S
PIN
For high speed mode, the R
S
pin is connected directly to GND2
(Pin 16 or Pin 20). The transition time of the CAN bus signals
are short as possible, allowing higher speed signaling. A shielded
cable is recommended to avoid EMI problems in high speed mode.
Slope control mode allows the use of unshielded twisted pair
wires or parallel pair wires as bus lines. The signal rise and fall
transition times are slowed to reduce EMI and ringing. The rise
and fall slopes are adjusted with the resistor (R
SLOPE
) connected
from R
S
to GND2. See Figure 6 for details.
The R
S
pin cannot be left floating.
INSULATION LIFETIME
All insulation structures eventually break down when subjected to
voltage stress over a sufficiently long period. The rate of insulation
degradation is dependent on the characteristics of the voltage
waveform applied across the insulation. Analog Devices conducts
an extensive set of evaluations to determine the lifetime of the
insulation structure within the ADM3053.
Accelerated life testing is performed using voltage levels higher
than the rated continuous working voltage. Acceleration factors for
several operating conditions are determined, allowing calculation
of the time to failure at the working voltage of interest. The values
shown in Table 5 summarize the peak voltages for 50 years of
service life in several operating conditions. In many cases, the
working voltage approved by agency testing is higher than the 50
year service life voltage. Operation at working voltages higher than
the service life voltage listed leads to premature insulation failure.
The insulation lifetime of the ADM3053 depends on the voltage
waveform type imposed across the isolation barrier. The iCoupler
insulation structure degrades at different rates, depending on
whether the waveform is bipolar ac, unipolar ac, or dc. Figure 29,
Figure 30, and Figure 31 illustrate these different isolation voltage
waveforms.
Bipolar ac voltage is the most stringent environment. A 50 year
operating lifetime under the bipolar ac condition determines
the Analog Devices recommended maximum working voltage.
In the case of unipolar ac or dc voltage, the stress on the insulation
is significantly lower. This allows operation at higher working
voltages while still achieving a 50 year service life. The working
voltages listed in Table 5 can be applied while maintaining the
50 year minimum lifetime, provided the voltage conforms to either
the unipolar ac or dc voltage cases. Any cross insulation voltage
waveform that does not conform to Figure 30 or Figure 31 must
be treated as a bipolar ac waveform, and its peak voltage must
be limited to the 50-year lifetime voltage value listed in Table 5.
0V
RATED PEAK VOLTAGE
09293-013
Figure 29. Bipolar AC Waveform
0V
RATED PEAK VOLTAGE
09293-014
Figure 30. DC Waveform
0V
RATED PEAK VOLTAGE
NOTES
1. THE VOLTAGE IS SHOWN AS SINUSODIAL FOR ILLUSTRATION
PURPOSES ONLY. IT IS MEANT TO REPRESENT ANY VOLTAGE
WAVEFORM VARYING BETWEEN 0 AND SOME LIMITING VALUE.
THE LIMITING VALUE CAN BE POSITIVE OR NEGATIVE, BUT THE
VOLTAGE CANNOT CROSS 0V.
09293-015
Figure 31. Unipolar AC Waveform