conditions, then the maximum transmission duration can be calculated to be
90.7ms. This maximum duration is applicable for applications where: 1) there
are no priority packet transmissions from the energy storage node; 2) subnet
and node numbers are in the range 0 through 15; and 3) if a six byte domain is
used, it is assigned to be equal to a Neuron Chip ID number.
Transmission
Abort
Packet
Retransmit
Figure 5.1
Supply Voltage vs. Packet Transmission
Products incorporating an energy storage power supply must have the power
management feature of the PLT-22 transceiver enabled (by using the appropriate
standard transceiver type) to prevent signal transmission if the supply voltage
drops too low. The transceiver's power management system is software
selectable through the use of transceiver programming options as described in
Chapter 3.
Energy Storage Capacitor-Input Power Supplies
A particularly cost-effective example of an energy storage power supply is the
capacitor-input power supply.
The most attractive feature of this supply is that
both V
A
and V
DD5
supplies can be built with just a few components for
approximately US$1.00-2.00.
Figure 5.2 illustrates the operation of a capacitor-input power supply. As shown in
the figure, a capacitor in series with the AC mains causes AC current to flow
through a zener diode, which acts as a shunt regulator. This regulator is selected to
limit the V
A
supply voltage to
≤
16V, the specified maximum value of the
transceiver's V
A
supply. An energy storage capacitor is connected across the shunt
regulator to provide current capacity required for transmission. Note that unused
source current flows through the shunt regulator, maximizing the zener diode
temperature when the supply load is at a minimum. Since the regulation voltages
of zener diodes above 10V have strong positive temperature coefficients, a pair of
forward-biased silicon diodes, which have negative temperature coefficients, have
been added in series with a slightly lower-voltage zener diode. Note that this type
of capacitor-input power supply would inherently attenuate communication signals
if not for the addition of a series inductor, as shown in figure 5.2.
L
ON
W
ORKS
PLT-22 Transceiver's User Guide
5-5
Summary of Contents for LONWORKS PLT-22
Page 6: ...iv Echelon...
Page 14: ...1 8 Introduction...
Page 67: ...LONWORKS PLT 22 Transceiver s User Guide 5 7 Figure 5 3 Capacitor Input Power Supply Schematic...
Page 92: ...6 10 Design and Test for Electromagnetic Compatibility...
Page 110: ...7 18 Communication Performance Verification...
Page 114: ...8 4 References...
Page 118: ...A 4 Appendix A...
