Specifications

PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Book 161
Energy Storage Linear Supplies
For products requiring minimal application current and safety isolation, an energy storage linear supply is a small
cost effective option. Consider a device based on a PL 3120 or PL 3170 Smart Transceiver consuming 10mA of
application and I/O current. Using a linear V
A
power supply and a linear regulator for the V
DD5
supply, the worst case
current requirements are presented in the table below.
Table 5.5 Worst-Case Device Current Consumption Example
Transmit Receive
V
A
Current 250mA 0.5mA
PL 3120/PL 3170 Smart
Transceiver
V
DD5
Current
13mA 13mA
Application & I/O
Current
10mA 10mA
78L05 Regulator
Current
5mA 5mA
Total 278mA 29mA
A traditional linear supply would require a transformer with an output current rating of ≥300mA. By taking
advantage of the PL Smart Transceiver’s power management feature, an energy storage linear supply can be built
with a 100mA transformer.
Figure 5.5 shows an example of an energy storage linear supply. This example supply meets the criteria listed in the
energy storage section of this chapter, for both C-band and A-band operation. With a transient load of 120mA for
140.7ms added to a constant 29mA receive load, this supply does not drop below 10.8V. This supply also maintains
≥9.0V after a 250mA load is added to the constant 29mA load for 140.7ms. Both of these criteria hold true even with
an AC line voltage that is 10% low and an output capacitance value that is 20% below nominal. In addition, this
example supply supports transmit duty cycles of ≥65% under typical conditions and ≥10% with worst case line
voltage and component tolerances.
Figure 5.5 Energy Storage Linear Power Supply
AC Line
Voltage
V
V
78L05
12.6 VAC @100 mA
4700 µF
25 V
±20%
+
A
DD5
(5V)
Gnd