IBM CMX58886CX Auxiliary Power CN3, Auxiliary Power Connector CN31, Pin Signal Function

Auxiliary Power (CN3)

WARNING If you connect power incorrectly, the module will almost certainly be destroyed. Please verify power connections to the module before applying power.

Power can be conveyed to the module either through the PCI-104-Plusbus (CN16) or through the Auxiliary Power connector (CN3). The cpuModule only requires +5 VDC and ground for operation; however, other modules in the system may require +12 VDC, –12 VDC, and –5 VDC. In these instances, the corresponding inputs on the Auxiliary Power Connector (CN3) may be used to supply these voltages.

Insufficient current supply will prevent your cpuModule from booting. The gauge and length of the wire used for connecting power to the cpuModule must be taken into consideration. Some power connectors have clip leads on them and may have significant resistance. Make sure that the input voltage does not drop below +4.8 V at the +5 V power pins. (Refer to Table 2 on page 10 for the cpuModule’s power requirements). A good rule of thumb is to use wire that can supply twice the power required by the system.

Note Connect two separate wires to the +5V pins (2 and 8) on the power connector to ensure a good power supply connection. We recommend that no less than 18 gauge wire be used and the length of this wire should not exceed 3 ft. Always measure the voltage drop from your power supply to the power pins on the cpuModule. The voltage at pins (2 and 8) should be +5V.

Table 7 Auxiliary Power Connector (CN3)1

Pin	Signal	Function
1	GND	Ground
2	+5 V	+5 Volts DC
3	+5V_STDBY	+5V Standby (ATX)
4	+12 V	+12 Volts DC
5	Reserved	Reserved
6	–12 V	–12 Volts DC
7	GND	Ground
8	+5 V	+5 Volts DC
9	GND	Ground
10	+3.3 V	See note below
11	PSON#	Power Supply On (ATX)
12	+3.3 V	See note below

1.For more information on the ATX style signals, +5V Standby and PSON#, refer to the Power Management section in Chapter 4, Using the cpuModule.

Note The +3.3 V pins (10 and 12) on the auxiliary power connector (CN3) are connected to the +3.3 V pins on the PC-104-Plus bus by default. These pins be configured to supply power to PC/104-Plus or PCI-104 expansion. If +3.3 V is supplied to the PC/104-Plus connector from the onboard power supply, the +3.3V pins (10 and 12) are not connected. Refer to the B3 description in Table 58 on page 82 for more information.

24 CMX58886CX cpuModule BDM-610000050 Rev A