
NET_A
NET_B
V+
INDUCTOR
Vcc
GND
CLK
L1
C2
C1
+5V
C3
Ro
Lo
Co1
Co2
To General
Circuitry
LPT-11
TO
NETWORK
To Sensitive
Low-power
Analog Circuits
To Higher-power
Resonant Loads
Figure 4.1
Post-Filtering of Vcc
Use the following guidelines to design the resistor and capacitor values for the R-C
filter:
1. Set the resistance value R
o
as high as possible without causing an
excessive voltage drop in the Vcc supplied to the filtered load;
2. Choose the capacitor value C
o1
to set the cutoff frequency of the R-C filter
at least 10x below the frequency (fn) of noise sensitivity in the circuit
being powered. That is, choose
C
o1
≥
10/(2
π
Rf
n
)
;
3. R
o
must be large enough to keep the “effective capacitance” of Co1 as seen
by the LPT-11 transceiver to less than 5% of the transceiver’s 22µF
output capacitor C2. This can be accomplished by ensuring that
R
o
≥
100
Ω
(C
o1
/1µF)
.
The L-C filter should be used for higher-power isolation (when the voltage drop
through R would be too high for the application circuit to tolerate). Use the following
steps to design the inductor and capacitor values for the L-C filter:
L
ON
W
ORKS
LPT-11 Transceiver User’s Guide
4-3
Содержание LonWorks LPT-11
Страница 20: ...2 10 Electrical Interface ...
Страница 40: ...5 14 Network Cabling and System Performance ...
Страница 70: ...B 4 Appendix B Differences Between LPT 10 and LPT 11 ...
Страница 76: ...C 6 Appendix C Checklist ...