System Features
EPM-32 Reference Manual
22
Note:
The +3.3VDC, +12VDC and -12VDC inputs on the main power connector are
only required for PC/104-
Plus
and PC/104 expansion modules that require the
voltages.
P
OWER
R
EQUIREMENTS
The EPM-32 requires only +5 volts (±5%) for proper operation. The voltage required for the RS-
232 ports are generated with a DC/DC converter. A variable low-voltage supply circuit provides
power to the CPU and other on-board devices.
The exact power requirement of the EPM-32 depends on several factors, including memory
configuration, CPU speed, peripheral connections, type and number of expansion modules and
attached devices. For example, PS/2 keyboards typically draw their power directly from the
EPM-32, and driving long RS-232 lines at high speed can increase power demand.
P
OWER
D
ELIVERY
C
ONSIDERATIONS
Using a VersaLogic approved power supply (VL-PS200-ATX) and power cable (CBR-1008) will
ensure high quality power delivery to the board. Customers who design their own power delivery
methods should take into consideration the guidelines below to ensure good power connections.
Also, the specifications for typical operating current do not include any off-board power usage
that may be fed through the EPM-32 power connector. Expansion boards and USB devices
plugged into the board will source additional power through the EPM-32 power connector.
Do not use wire smaller than 22 AWG. Use high quality UL 1007 compliant stranded
wire.
The length of the wire should not exceed 18".
Avoid using any additional connectors in the power delivery system.
The power and ground leads should be twisted together, or as close together as possible
to reduce lead inductance.
A separate conductor must be used for each of the power pins.
All power input pins and all ground pins must be independently connected between the
power source and the power connector.
Use a high quality power supply that can supply a stable voltage while reacting to widely
varying current draws.
