RD014-RGUIDE-01
2018-03-15
Rev. 1
6
/
19
© 2018
Toshiba Electronic Devices & Storage Corporation
Just for reference, Figure 2.3 shows an example of an output waveform when the common-
mode voltage V
CM
has a very large dV/dt rate with 60kV/μs. The V
OUT
waveform has a noise
spike caused by V
CM
sudden change. This noise spike could cause a total system malfunction if
it becomes larger.
Figure 2.3 Example of an output waveform of the TLP7820 when a common-mode
voltage (V
CM
) with a very large slew rate is applied
About output linearity characteristics
When system feedback needs using isolation amplifier detecting current fluctuations, it is
important for input-output linearity characteristics to control system properly. The output of an
isolation amplifier with bad linearity characteristics does not respond accurately with specific
input so there are lacking of the stability and accuracy of a system. In the trend of increasing
speed, accurate control is required for inverters and it is important for isolation amplifier to
minimize the output errors. Although an electronic circuit or software can be used to correct
output errors, both methods are impractically complicated and difficult, considering variations
in device characteristics. Using an isolation amplifier with high precision linearity characteristics
is more practical. Figure 2.4 shows a test circuit for measuring the linearity characteristics of
an isolation amplifier.
Figure 2.4 Example of a nonlinearity test circuit
V
CM
(V
OUT+
) - (V
OUT-
)
V
CM
: 1 kV/div
ｄ
V/dt = 60 kV/μs
t: 80 ns/div
(V
OUT+
) - (V
OUT-
): 100 mV/div
