Ampro Corporation 486E - Manual (Page 23)

Product Reference
2–7
Power Requirements
The Little Board/486e CPU operates on +5VDC (±5%). The ±9V RS-232 voltages are generated on
board. The exact power requirement of the Little Board/486e CPU system depends on several
factors such as:
! Amount of installed DRAM
! Number of installed byte-wide memory devices
! Peripheral connections
! MiniModule products (if installed)
! Other expansion boards attached to the PC/104 bus
For example: AT keyboards draw power from the motherboard, and there can be some loading from
the serial and parallel ports. Consult the specifications in Chapter 3 for the basic power
requirements of your model.
If a switching power supply is used it must regulate properly with the system load. Some switching
power supplies do not regulate properly unless they are loaded to some minimum value. If this is
the case, consult the manufacturer for information regarding additional loading or use another
supply or another type of power source such as a linear supply, or batteries.
Backup Battery
With only the real-time clock drawing current, the backup battery on the Little Board/486e should
last 10 years. If it supplies only the clock, replace the battery every 10 years as a routine
maintenance procedure.
Cooling Requirements
Adequate airflow should be provided to maintain an ambient temperature at or below 70°C within
the case. For Extended Temperature Qualified products, the temperature must remain at or below
85°C. Little Board/486e CPU uses a 486DX/System Logic Chip rated at 3.3V to minimize power
drain. In addition a heat sink is provided for the CPU. The majority of the current draw and heat
generated come from the:
! 486 CPU
! DRAM
! video controller
! 486DX/System Logic Chip