Isolated Node Providing Power to
the Network
(network) side of the two
will not “lock-up” if either AC line
power to the node is lost or the
node powered-off. Specifically,
when input power (VDD1) to the
HCPL-x710 located in the
transmit path is eliminated, a
RECESSIVE bus state is ensured
as the HCPL-x710 output voltage
(VO) go HIGH.
optocouplers. This method is
recommended when there are a
limited number of devices on the
network that don’t require much
power, thus eliminating the need
for separate power supplies.
Figure 21 shows a node providing
power to the network. The AC line
powers a regulator which
provides five (5) volts locally. The
AC line also powers a 24 volt
isolated supply, which powers the
network, and another five-volt
regulator, which, in turn, powers
the transceiver and isolated
More importantly, the unique
“dual-inverting” design of the
HCPL-x710 ensure the network
AC LINE
DEVICENET NODE
NODE/APP SPECIFIC
uP/CAN
5 V REG.
ISOLATED
SWITCHING
POWER
GALVANIC
ISOLATION
BOUNDARY
HCPL
x710
HCPL
x710
SUPPLY
5 V REG.
TRANSCEIVER
DRAIN/SHIELD
SIGNAL
V+ (SIGNAL)
V– (SIGNAL)
V+ (POWER)
V– (POWER)
POWER
Figure 21. Isolated node providing power to the network.
14
AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
