RD014-RGUIDE-01
2018-03-15
Rev. 1
8
/
19
© 2018
Toshiba Electronic Devices & Storage Corporation
Primary-side supply current
Figure 2. 6 shows the relationships between the input voltage and the primary-side supply
current of the TLP7820 ( B) side) and a competitor
’
s isolation amplifier ( A) side). The
primary-side supply current of the competitor
’
s isolation amplifier increases with input voltage
while the TLP7820 has a unique digital encoder/decoder technology to maintain the primary-
side supply current at almost a constant level around 9 mA (typical) over a range of input
voltage (recommend operating range: -0.2 to +0.2 V). This contributes reduction of the
maximum circuit current, simplifying the design of a primary-side power supply.
A) Competitor A B) TLP7820
Figure 2.6 Relationships between the input voltage and the primary-side supply
current of isolation amplifiers
Figure 2.7 (B) shows the changes in the primary-side supply current in response to input
voltage changes at a given frequency in Figure 2.7 (A).
A) Input voltage changes B) Primary-side supply current waveforms
Figure 2.7 Primary-side supply current waveforms in response to input voltage
changes
The primary-side supply current of the competitor
’
s isolation amplifier changes between 9
mA and 13 mA in response to changes in input voltage while the primary-side supply current
TLP7820
Competitor
