full load while drawing only 3mA from the negative supply.
鈮?/div>
5). Thus, the
PWS725A/726A can power more circuits than is at first
apparent.
ISOLATION VOLTAGE RATINGS
Because a long-term test is impractical in a manufacturing
situation, the generally accepted practice is to perform a
production test at a higher voltage for some shorter period of
time. The relationship between actual test conditions and the
continuous derated maximum specification is an important
one. Burr-Brown has chosen a deliberately conservative
one: VDC
TEST
= (2
X
VACrms
CONTINUOUS RATING
) + 1000V for
ten seconds. This choice is appropriate for conditions where
system transient voltages are not well defined.
(1)
Where the
real voltages are well-defined or where the isolation voltage
is not continuous, the user may choose a less conservative
derating to establish a specification from the test voltage.
NOTE: (1) Reference National Electrical Manufacturers Association (NEMA)
Standards Parts ICS I-109 and ICS I-111.
OUTPUT SYNC SIGNAL
To allow synchronization of an ISO120 or ISO121 isolation
amplifier, the PWS725A and PWS726A have an OUTPUT
SYNC signal at pin 29. It should be connected as shown in
Figure 5 to keep capacitive loading of pin 29 to a minimum.
If output sync is not used, leave pin open.
4
PWS725A/726A
29
20k鈩?/div>
20pF
Ext Osc
Connection
of
ISO120
or
ISO121
FIGURE 5. Synchronization with ISO120 or ISO121 Isola-
tion Amplifier.
庐
PWS725A/726A
6
1
2
3
4
5
6
