Datasheet ADUM7234 (Analog Devices) - 9

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Data Sheet ADuM7234
The insulation lifetime of the ADuM7234 depends on the
V 5V 15V DD1 GND1
voltage waveform type imposed across the isolation barrier.
V 15V DDA AND VDDB
The iCoupler insulation structure degrades at different rates
GNDA AND GNDB 15V ΔV
depending on whether the waveform is bipolar ac, unipolar
VDDA AND VDDB Δt GND
ac, or dc. Figure 14, Figure 15, and Figure 16 il ustrate these
A AND GNDB 5V ΔV 15V VDD1 Δt
006 different isolation voltage waveforms.
GND1
07990- Bipolar ac voltage is the most stringent environment. The goal Figure 11. Common-Mode Transient Immunity Waveforms, Input to Output of a 50-year operating lifetime under the bipolar ac condition determines the maximum working voltage recommended by
V 15V 15V DDA/VDDB
Analog Devices.
GNDA/GNDB V 15V DDB/VDDA
In the case of unipolar ac or dc voltage, the stress on the insulation
GNDB/GNDA
is significantly lower. This al ows operation at higher working
15V ΔV VDDA/VDDB Δt
voltages while still achieving a 50-year service life. The working
GNDA/GNDB 15V ΔV 15V VDDB/VDDA Δt
voltage listed in Table 3 can be applied while maintaining the 007
GNDA/GNDB
50-year minimum lifetime, provided that the voltage conforms 07990- Figure 12. Common-Mode Transient Immunity Waveforms to either the unipolar ac or dc voltage cases. Any cross-insulation Between Outputs voltage waveform that does not conform to Figure 15 or Figure 16 should be treated as a bipolar ac waveform, and its peak voltage
VDDA/VDDB
should be limited to the 50-year lifetime voltage value listed in Table 3.
ΔVDD VDDA/VDDB Δt
008 Note that the voltage presented in Figure 15 is shown as sinu-
GNDA/GNDB GNDA/GNDB
07990- soidal for il ustration purposes only. It is meant to represent any Figure 13. Transient Immunity Waveforms, Output Supplies voltage waveform varying between 0 V and some limiting value.
INSULATION LIFETIME
The limiting value can be positive or negative, but the voltage cannot cross 0 V. All insulation structures eventual y break down when subjected to voltage stress over a sufficiently long period. The rate of insu- lation degradation depends on the characteristics of the voltage
RATED PEAK VOLTAGE
waveform applied across the insulation. In addition to the testing
0V
009 performed by the regulatory agencies, Analog Devices conducts 07990- an extensive set of evaluations to determine the lifetime of the Figure 14. Bipolar AC Waveform insulation structure within the ADuM7234. Analog Devices performs accelerated life testing using voltage
RATED PEAK VOLTAGE
levels higher than the rated continuous working voltage. Accel- eration factors for several operating conditions are determined. 010 These factors al ow calculation of the time to failure at the actual
0V
07990- working voltage. Table 3 lists the peak voltage for 50 years of Figure 15. Unipolar AC Waveform service life for a bipolar ac operating condition and the maximum Analog Devices recommended working voltage. In many cases,
RATED PEAK VOLTAGE
the approved working voltage is higher than the 50-year service life voltage. Operation at these high working voltages can lead 011 to shortened insulation life in some cases.
0V
07990- Figure 16. DC Waveform Rev. B | Page 9 of 12 Document Outline Features Applications General Description Functional Block Diagram Table of Contents Revision History Specifications Electrical Characteristics Package Characteristics Insulation and Safety-Related Specifications Recommended Operating Conditions Regulatory Information Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics Applications Information Common-Mode Transient Immunity Insulation Lifetime Outline Dimensions Ordering Guide