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Product Facts
Issue: May 2009
ATX compliant Power Supply Option (internal connector)
The mainboard D2703-S offers a standard ATX power supply connector as shown in the figure and table below.
Figure ATX Power Supply Connector
Table ATX Power Supply Connector Pin Assignment (D2703-S)
Pin
1
2
3
4
5
6
7
8
9
10
Notes to Pin Assigment
• The mainboard D2703-S uses pin 18 of the ATX connector for an internal single 24 V DC supply (see
section "24 V DC power supply option" below for details).
• Typically pin 18 of a standard ATX power supply is "not connected". Former ATX power supplies provided -
5 V via pin 18 which is no longer required for state-of-the-art mainboards.
• If the ATX power supply used for a specific implementation still delivers -5 V via pin 18, this causes no
damage to the mainboard D2703-S.
• In general, pin 3 of an ATX power supply is connected to GND. The mainboard D2703-S uses pin 3 to
detect if an ATX power supply is connected or not.
• Instead of a standard 20-pin ATX power supply, a 24-pin BTX power supply can be connected to the
mainboard D2703-S as well. Pins 21 to 24 will not be used.
The following table lists the requirements for the electrical characteristics that must be met by an ATX power
supply to operate a D2703-S mainboard properly. Please also pay attention to the specific notes.
• During power-on/power-off, the power supply must fulfill the general ATX requirements regarding ramp-
up/down timing for all supply voltages and the Powergood output.
• The ATX power supply input of the D2703-S has capacitive loads which need to be covered by the power
supply during power ramp-up. See the table below for the capacitance values on each voltage rail.
• The ATX power supply must be approved according to IEC60950-1.
Table ATX Power Supply Requirements (D2703-S)
Source
Voltage
(ATX / BTX)
+12 V
Main Power
Product: Power Select
Signal Assignment
+3.3 V
+3.3 V
ATX Detect (low asserted)
+5 V
GND
+5 V
GND
Powergood (high asserted)
+5 V
(Auxiliary)
AUX
+12 V
PS Load (min),
Tolerance
see note 1)
0.15 A
Pin
11
12
13
14
15
16
17
18
19
20
Mainboard
(max)
Current (typ.),
see note 2)
± 5%
0.7 A
Signal Assignment
+3.3 V
-12 V
GND
PS on (low asserted)
GND
GND
GND
+24 V
+5 V
+5 V
Mainboard
Capacitive Input
Current (max),
see note 3)
2.8 A
1000 µF
Page
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