Omega A2400 User Manual
Page 51
Chapter 7
Power Supply
A2400 modules may be powered with an unregulated +10 to +30Vdc.
Power-supply ripple must be limited to 5V peak-to-peak, and the instanta-
neous ripple voltage must be maintained between the 10 and 30 volt limits
at all times. All power supply specifications are referred to the module
connector; the effects of line voltage drops must be considered when the
module is powered remotely.
The A2400 modules employ an on-board switching regulator to maintain
good efficiency over the 10 to 30 volt input range; therefore the actual
current draw is inversely proportional to the line voltage. The A2400
consume a maximum of .5 watts and this figure should be used in
determining the power supply current requirement.
In some cases, the A2400 may be operated by “stealing” power from a host
computer or terminal. Many computers provide a +15 volt output on the RS-
232C DB-25 connector.
Small systems may be powered by using wall-mounted calculator-type
modular power supplies. These units are inexpensive and may be obtained
from many retail electronics outlets.
A2400 modules may be locally powered. This eliminates the voltage drops
on the Ground lead which may interfere with communications signals. In this
case the V+ terminal is connected only to the local power supply. The
Ground terminal must be connected back to the host to provide a ground
return for the communications loop.
The A2400 modules are protected against power supply reversals.