ADUM1234BRWZ-RL1 AD [Analog Devices], ADUM1234BRWZ-RL1 Datasheet - Page 9

• Manufacturer Part Number: ADUM1234BRWZ-RL1
• Description: Isolated, Precision Half-Bridge Driver, 0.1 A Output
• Manufacturer: AD [Analog Devices]

V
GND
INSULATION LIFETIME
All insulation structures eventually break down when subjected
to voltage stress over a sufficiently long period. The rate of
insulation degradation depends on the characteristics of the
voltage waveform applied across the insulation. In addition to
the testing performed by the regulatory agencies, Analog
Devices conducts an extensive set of evaluations to determine
the lifetime of the insulation structure within the ADuM1234.
Analog Devices performs accelerated life testing using voltage
levels higher than the rated continuous working voltage.
Acceleration factors for several operating conditions are
determined. These factors allow calculation of the time to
failure at the actual working voltage. Table 7 summarizes the
peak voltages for 50 years of service life for a bipolar ac
operating condition and the maximum Analog Devices
recommended working voltages. In many cases, the approved
working voltage is higher than the 50-year service life voltage.
Operation at these high working voltages can lead to shortened
insulation life in some cases.
The insulation lifetime of the ADuM1234 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 14, Figure 15, and Figure 16 illustrate these
different isolation voltage waveforms.
Bipolar ac voltage is the most stringent environment. The goal
of a 50-year operating lifetime under the ac bipolar condition
DDA
A
/V
/GND
DDB
B
Figure 13. Transient Immunity Waveforms, Output Supplies
ΔV
Δt
DD
GND
V
DDA
A
/GND
/V
DDB
B
Rev. 0 | Page 9 of 12
determines the maximum working voltage recommended by
Analog Devices.
In the case of unipolar ac or dc voltage, the stress on the insu-
lation is significantly lower. This allows operation at higher
working voltages while still achieving a 50-year service life.
The working voltages listed in Table 7 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 15
or Figure 16 should be treated as a bipolar ac waveform and its
peak voltage should be limited to the 50-year lifetime voltage
value listed in Table 7. Note that the voltage presented in Figure 15
is shown as sinusoidal for illustration purposes only. It is meant
to represent any voltage waveform varying between 0 V and
some limiting value. The limiting value can be positive or
negative, but the voltage cannot cross 0 V.
RATED PEAK VOLTAGE
RATED PEAK VOLTAGE
RATED PEAK VOLTAGE
0V
0V
0V
Figure 15. Unipolar AC Waveform
Figure 14. Bipolar AC Waveform
Figure 16. DC Waveform
ADuM1234