Input power for Prometheus-LC may be supplied either through J11 from an external supply or directly through the PC/104 bus power pins if a PC/104 power supply is used with the CPU.
Prometheus-LC requires only +5VDC input power to operate. All other required voltages are generated on board with miniature switching regulators. However since the PC/104 bus includes pins for ±5V and ±12V, these voltages may be supplied through J11 if needed. The +5V and +12V voltages are controlled by the ATX power manager switches, while -5V and -12V are routed directly to the corresponding pins on PC/104 bus and are not controlled by the ATX function.
Make sure that the power supply used has enough current capacity to drive your system. The Prometheus-LC CPU requires up to 1.1A on the +5V line. If you have a disk drive or other modules connected, you need additional power. In particular, many disk drives need extra current during startup. If your system fails to boot properly, or if disk accesses do not work properly, the first thing to check is the power supply voltage level. Many boot-up problems are caused simply by insufficient voltage due to excess current draw on the +5V supply.
Multiple +5V and Ground pins are provided for extra current carrying capacity if needed. Each pin is rated at 3A max (15W). For the Prometheus-LC CPU, the panel I/O board, and a video board, 3A is sufficient, so +5 and Ground require only a single wire each. In this case the first 4 pins may be connected to a standard 4-pin miniature PC power connector if desired.
For a larger PC/104 stack the total power requirements should be calculated to determine whether additional wires are necessary.
ATX control enables the +5V and +12V power to be switched on and off with an external momentary switch. A short press on the switch will turn on power, and holding the switch on for 4 seconds or longer will turn off power.
Diamond Systems’ cable no. 698009 mates with J11. It provides 9 color-coded wires with stripped and tinned leads for connection to user-supplied power sources. This cable may also be used with Diamond Systems’ Jupiter-MM series power supplies in vehicle-based applications. In this configuration, the input power is supplied to the Jupiter-MM board, and the Jupiter-MM output power is connected to J11 on the CPU using cable 698009. When used in this way, make sure the two red +5V wires are both connected to the +5V output screw terminal on Jupiter-MM.
Prometheus-LC CPU User Manual V1.0 | Page 9 |
