Siemens SPC4000 Installation & Configuration Manual page 114

Appendix
16.5 Appendix F: Powering Expanders from the Auxiliary Power
Terminals
114
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Fire Safety & Security Products
The Auxiliary 12 V power terminals on the SPC Controller (0 V, 12 V) share a
power supply (750 mA) with the Darlington outputs (OP4, OP 5, OP6) enabling
connection to a number of external devices and/or Expanders to the Controller.
To calculate the number of Expanders/Keypads that can safely be powered from
the auxiliary power terminals, add the total maximum current draw from all of the
Expanders/Keypads to be powered and determine if this total is less than 750 mA.
A table containing the current draw for each type of Expander is below. The max
current values assume all relays on the Expanders are powered and no devices
are connected to the Auxiliary power terminals on each Expander.
Expander
SPCE650 Expander with
8 Input / 2 Output
SPCE450 Expander with
8 Output
SPCK420 LCD Keypad
SPCK421 LCD Keypad with Card Reader
(*) – The maximum current value displayed for the Keypad is with the backlight ON.
Tab. 29 Current draw for each type of Expanders
Expander 1 Current (mA) + Expander 2 Current (mA) + ..... <750 mA
If the Darlington outputs (OP4, OP5 & OP6) are already powering external devices
then the power supplied to these devices from the 750 mA supply must be
subtracted to determine the amount of available power from the Auxiliary power
terminals (0 V, 12 V).
Quiescent Current
45 mA
55 mA
60 mA
90 mA
Max Current
80 mA
190 mA
70 mA
110 mA
09.2008