Data Sheet ADuM5410/ADuM5411/ADuM5412
Rev. 0 | Page 27 of 29
THERMAL ANALYSIS
The ADuM5410/ADuM5411/ADuM5412 consist of four internal
die attached to a split lead frame with two die attach pads. For the
purposes of thermal analysis, the die is treated as a thermal unit,
with the highest junction temperature reflected in the θJA value
from Table 21. The value of θJA is based on measurements taken
with the devices mounted on a JEDEC standard, 4-layer board
with fine width traces and still air. Under normal operating
conditions, the ADuM5410/ADuM5411/ADuM5412 can
operate at full load across the full temperature range without
derating the output current.
PROPAGATION DELAY RELATED PARAMETERS
Propagation delay is a parameter that describes the time it takes
a logic signal to propagate through a component (see Figure 33).
The propagation delay to a logic low output may differ from the
propagation delay to a logic high.
INPUT (V
Ix
)
OUTPUT (V
Ox
)
t
PLH
t
PHL
50%
50%
14695-032
Figure 33. Propagation Delay Parameters
Pulse width distortion is the maximum difference between these
two propagation delay values and is an indication of how
accurately the input signal timing is preserved.
Channel to channel matching refers to the maximum amount
the propagation delay differs between channels within a single
ADuM5410/ADuM5411/ADuM5412 component.
Propagation delay skew refers to the maximum amount the
propagation delay differs between multiple ADuM5410/
ADuM5411/ADuM5412 components operating under the
same conditions.
EMI CONSIDERATIONS
The dc-to-dc converter section of the ADuM5410/ADuM5411/
ADuM5412 components must, of necessity, operate at a very high
frequency to allow efficient power transfer through the small
transformers, which creates high frequency currents that can
propagate in circuit board ground and power planes, causing
edge and dipole radiation. Grounded enclosures are recommended
for applications that use these devices. If grounded enclosures are
not possible, follow good RF design practices in the layout of
the PCB. Follow the layout techniques described in the PCB
Layout section. See the AN-0971 Application Note for the most
current PCB layout recommendations for the ADuM5410/
ADuM5411/ADuM5412.
POWER CONSUMPTION
The VDDP power supply input only provides power to the converter.
Power for the data channels is provided through VDD1 and VDD2.
These power supplies can be connected to VDDP and VISO if desired,
or the supplies can receive power from an independent source.
Treat the converter as a standalone supply to be utilized at the
discretion of the designer.
The VDD1 or VDD2 supply current at a given channel of the
ADuM5410/ADuM5411/ADuM5412 isolator is a function of
the supply voltage, the data rate of the channel, and the output
load of the channel.
To calculate the total VDD1 and VDD2 supply current, the supply
currents for each input and output channel corresponding to
VDD1 and VDD2 are calculated and totaled. Figure 18 and
Figure 19 show per channel supply currents as a function of
data rate for an unloaded output condition. Figure 20 shows the
per channel supply current as a function of data rate for a 15 pF
output condition. Figure 21 through Figure 26 show the total
VDD1 and VDD2 supply current as a function of data rate for
ADuM5410/ADuM5411/ADuM5412 channel configurations.
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 as well as on the materials
and material interfaces.
The two types of insulation degradation of primary interest are
breakdown along surfaces exposed to the air and insulation wear
out. Surface breakdown is the phenomenon of surface tracking
and the primary determinant of surface creepage requirements
in system level standards. Insulation wear out is the phenomenon
where charge injection or displacement currents inside the
insulation material cause long-term insulation degradation.
Surface Tracking
Surface tracking is addressed in electrical safety standards by
setting a minimum surface creepage based on the working voltage,
the environmental conditions, and the properties of the insulation
material. Safety agencies perform characterization testing on the
surface insulation of components that allows the components to be
categorized in different material groups. Lower material group
ratings are more resistant to surface tracking and, therefore, can
provide adequate lifetime with smaller creepage. The minimum
creepage for a given working voltage and material group is in
each system level standard and is based on the total rms voltage
across the isolation, pollution degree, and material group. The
material group and creepage for the digital isolator channels are
presented in Table 23.
Insulation Wear Out
The lifetime of insulation caused by wear out is determined by
its thickness, material properties, and the voltage stress applied.
It is important to verify that the product lifetime is adequate at
the application working voltage. The working voltage supported
by an isolator for wear out may not be the same as the working
voltage supported for tracking. The working voltage applicable
to tracking is specified in most standards.