Application Note; Overview; Ex12X2 And Ex12X6 Power Consumption Calculation - VTI Instruments Metek EX1202 User Manual

VTI Instruments Corp.
A
PPLICATION
O
VERVIEW
As with any backplane-based system where modules share power, such as VXI and PXI, the
possibility exists where a combination of plug-in modules may exceed the maximum power
available from the power supply. There are two limitations that govern power delivery by a
supply: 1) the maximum power of the power supply and 2) the maximum power that can be
delivered to a single slot. To avoid potential power-related issues, these two limitations cannot be
exceeded.
As a reference, the power specifications for the EX1200 mainframes are provided which indicate
the limitations on the power supplies and the slots.
P S
OWER PECIFICATIONS
1
A P
VAILABLE OWER
EX1202/06/62/66
EX1208/68
1
U P
SEABLE OWER
EX1202/EX1206
EX1262/EX1266
EX1208/68 (Slots 1 – 5)
EX1208 (Slots 6 – 10)
EX1268 (Slots 6 – 10)
EX1208/68 (Slots 11 – 16)
*The EX12x8 mainframe is powered by four power supplies and each power supply is used for a finite number of mainframe slots. For more
information, see the Power Consumption in Appendix B.
M C P R
AXIMUM URRENT ER AIL
EX1202/EX1206
EX1262/EX1266
EX1208/68 (Slots 1 – 5)
EX1208/68 (Slots 6 – 10)
EX1208/68 (Slots 11 – 16)
M C C
AXIMUM URRENT ARRYING
3.3 V rail
5 V rail
24 V rail
1
Note : The EX12x8 mainframe is powered by four power supplies and each power supply is used for a finite number of mainframe slots.
For more information, see the Power Consumption in Appendix B.
2
Note : For more information on calculating power consumption, please refer to the Power Consumption in Appendix B.
3
Note : These values indicate the maximum current provided by the power supply. This value is limited by the carrying capacity for that
rail. See the Maximum Current Carrying Capacity per Slot specification for more information.
EX12 2 EX12 6 P
X AND X
For the EX12x2 and EX12x6 mainframes, the total power useable (P
(P ), 5 V (P
3.3V
mainframe being used. These mainframes are powered by a single power supply and current on
the 3.3 V rail is derived from the 24 V rail with an efficiency of 80%. When calculating the total
power consumption of the cards installed in an EX12x2/x6 mainframe, the following conditions
must be satisfied:
1) P
24V
2) P
24V
3) P
5V
4) P
3.3V
5) No rail can exceed the maximum current per rail. Particular attention should be paid to the
24 V rail.
154
N
OTE
120 W
120 W per segment, 360 W total
115 W
110 W
102 W
97 W
102 W
102 W
1,2
3.3 V
6.00 A
6.00 A
14.99 A
14.99 A
14.99 A
C P S
APACITY ER LOT
6 A
3.75 A
1.6 A
C
OWER ONSUMPTION
), and 24 V (P
5V 24V
≤ P
+ P + P
5V 3.3V USEABLE
≤ 84 W
+ P
3.3V
≤ 75 W
≤ 24 W
5 V
13.420 A
13.410 A
13.582 A
13.362 A
13.355 A
C
ALCULATION
) rails is defined by the Useable Power specification for the
24 V
3.320 A
3.074 A
2.950 A
2.950 A
2.950 A
) between the 3.3 V
USEABLE
Appendix B