Maximum current rating of the +5V terminal in PXI 7813R

[VGR]

Hi,

I am bit confused about the maximum current rating of the +5V terminal of PXI 7813R specified in "NI R Series Multifunction RIO Specifications". I understand that there four connectors for PXI 7813R and in each connector there are two +5V terminals. If I use this +5V to give power for my external circuit, what is the maximum current that can be supplied by each terminal?

Thanks

Reju

[crossrulz]

Sheet 5 in the bottom right corner of the spec gives all of your answers.

+5V terminal
Connector 0.................................0.5 A max
Connector 1.................................0.5 A max
Connector 2.................................0.5 A max
All connectors .............................1.5 A max

[VGR]

Hi, thanks for the replay.

I saw this specification, but I am confused because these values are under the heading “Power requirement”. So I thought it is the power required by PXI-7813R. Also, in page 5 foot note 3, it is mentioned that the maximum terminal current for all the connectors is 100 mA unless disk drive connector is installed. In my case I don’t have the disk drive connector. Does it mean that I can get only 100 mA maximum? Another confusion is, for PXI-7813R there are four connectors but here only three connectors are mentioned (connector 0, 1 and 2). Since one connector has two +5V terminals, does it mean that one terminal can supply only 0.25 A  (50 mA without disk drive) as one connector can supply only 0.5 A (100 mA without disk drive)? In page 6, at the top of the first column, it is given that “Power available at I/O connectors...4.50 to 5.25 VDC at 1 A total, 250 mA per I/O connector pin”. Which are these terminals?

Thanks

Reju

[crossrulz]

The 100mA footnote was only for PCIe cards.  Since you are using a PXI, you can ignore that one.

My understanding is that the two +5V terminals on a connector are directly tied together.

The page 6 spec says that you will have between 4.5V and 5.25V when you are drawing 1A.

I don't know why it doesn't mention connector 4.  Maybe connector 4 actually doesn't have +5V.  That's something I'll have to look at one of these days.

But the main thing you need is 0.5A per connector.

[VGR]

Hi,

Thanks for the reply. Hope you can clarify why only three connectors are shown even though there are 4 four connectors for PXI-7813R.

Reju

[VGR]

In PXI-7813R, can I connect the +5V terminals from different connectors together? For example, since one +5V terminal can only supply maximum 0.5 A, if I need more than 0.5 A current, can I connect two or more +5V terminals together?  

[crossrulz]

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@VGR wrote:

In PXI-7813R, can I connect the +5V terminals from different connectors together? For example, since one +5V terminal can only supply maximum 0.5 A, if I need more than 0.5 A current, can I connect two or more +5V terminals together?  

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In theory, sure.  But it always makes me feel uneasy about putting fuses in parallel with each other.  How much current do you need?  What are you trying to do with the +5V?

[VGR · Accepted solution]

I got your point, in that case I can do it separately.

Thanks

Reju

[redfrank]

We are currently using PCI-7833R, PCIe-7852R and PXI-7853R boards.

I'm still confused by the data sheet and manual for this 5V supply and think NI need to update it.

The discussion here talks about not wiring multiple outputs from multiple connectors to draw more current as multiple fuses would be in parallel, yet there is only one fuse fitted to the board, so this is protecting all 3 connectors.

Also, the Littelfuse 0453004 fuse when I googled it revealed itself to be 4A!

Athe original poster said, can we draw 0.5A from each of the 2 pins on each connector, or only 0.25A each?

The manual for the R-series cards states:

"The power rating on most devices is +4.75 to +5.25 VDC at 1 A.

Refer to the NI R Series Multifunction RIO Specifications document,

available at ni.com/manuals, to obtain the power rating for your device."

but the spec sheet it then refers to states 0.5A on each connector or 1.5A in total, with no 1A in sight, and a caveat that PCIe boards will be 100mA if the disk drive connector isn't used.