Why so many connectors for SATA power?

[John Smith]

Why does a SATA drive have so many connectors for the power supply?

Why does the SATA spec seem to specify so many connectors? (I think there
are 15.)

 

[J. Clarke]

Why does a SATA drive have so many connectors for the power supply?

Why does the SATA spec seem to specify so many connectors? (I think there
are 15.)

??? There's only one SATA power connector on any drive that I've examined.
Do you mean contacts? If so I suspect it's to allow a relatively small
wire size for the individual conductors.

 

[Rod Speed]

Why does a SATA drive have so many connectors for the power supply?

Basically for convenience when so many systems dont have SATA
power available from the power supply. And that isnt just a matter
of the mechanical detail so a purely mechanical adapter can be used,
the older ATA power connector doesnt have 3.3V available at all.

Why does the SATA spec seem to specify so many connectors?
(I think there are 15.)

You mean connections, not connectors. There are just two power
connectors, the SATA power connector and the legacy power connector.

There are duplicates of all the connectors in the SATA
connector, just like there is with the power connector
to the motherboard, basically to share the load over a
number of connections and so the current thru each one.

There is also a precharge/2nd mate for each voltage.
That basically sequences the connection for that voltage.

There are basically 4 voltages, OV, 3.3V, 5V, 12V and
3 connections for each voltage, 5 grounds, and one reserved.

 

[Arno Wagner]

Why does a SATA drive have so many connectors for the power supply?

Why does the SATA spec seem to specify so many connectors? (I think there
are 15.)

I you mean "contacts", simple:
The standard molex connectors are rated for 5A. The thin wire
pressing on PCB-style connectors can take maybe 1A or less per
contact, so you have to use several.

Underlying reason may be that they did not want to use
any existing connectors and wanted the power connector
to match the data connector as closely as possible.

Arno

 

[J. Clarke]

I you mean "contacts", simple:
The standard molex connectors are rated for 5A. The thin wire
pressing on PCB-style connectors can take maybe 1A or less per
contact, so you have to use several.

Underlying reason may be that they did not want to use
any existing connectors and wanted the power connector
to match the data connector as closely as possible.

Bear in mind that SATA is intended to be hot-swappable. That means
connectors amenable to easy plugging into and unplugging from a backplane.
They could probably have used some variant on the SCA connector but that
would have far more contacts than SATA needs and would allow SATA drives to
be easily confused with SCA drives, neither of which is a particularly
desirable state of affairs.

 

[Arno Wagner]

Arno Wagner wrote:

Bear in mind that SATA is intended to be hot-swappable. That means
connectors amenable to easy plugging into and unplugging from a backplane.
They could probably have used some variant on the SCA connector but that
would have far more contacts than SATA needs and would allow SATA drives to
be easily confused with SCA drives, neither of which is a particularly
desirable state of affairs.

Yes, that could be it. Hot-plugging is a newer trend, so the choice of
existing _cheap_ connectors was possibly very limited. Same problem perhaps
when they used a new system for the USB and Firewire connectrs...

And you want to avoid the case where some existing hardware uses
the same connector with possible disastrous effects if somebody
plugs it in...

Arno

 

[Folkert Rienstra]

Bear in mind that SATA is intended to be hot-swappable. That means
connectors amenable to easy plugging into and unplugging from a backplane.
They could probably have used some variant on the SCA connector but that
would have far more contacts than SATA needs

Not if they used a SCA40 variant.

and would allow SATA drives to be easily confused with SCA drives,

Not if they used a 'variant'.

 

[Folkert Rienstra]

Yes, that could be it.

Hot-plugging is a newer trend,
'Clue'less.

so the choice of
existing _cheap_ connectors was possibly very limited. Same problem perhaps
when they used a new system for the USB and Firewire connectors...

And you want to avoid the case where some existing hardware uses the
same connector with possible disastrous effects if somebody plugs it in...

That's why you don't do that (preferably) or make sure they differ in some
way or other so that they can't be interchanged. Simplest would be to mount it upside down.

And lots of removable trays used the same 50pin centronics connector
for IDE as well as SCSI.

 

[Arno Wagner]

'Clue'less.

Thanks, and the same back to you.

That's why you don't do that (preferably) or make sure they differ in some
way or other so that they can't be interchanged. Simplest would be
to mount it upside down.

See above.

And lots of removable trays used the same 50pin centronics connector
for IDE as well as SCSI.

That is called "shoddy design".

Arno