Why so many connectors for SATA power?

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Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

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.)
 
Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

John Smith wrote:

> 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.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
 
Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

Previously John Smith <m@ixo.com> wrote:
> 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
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus
 
Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

Arno Wagner wrote:

> Previously John Smith <m@ixo.com> wrote:
>> 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.

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

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
 
Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

John Smith <m@ixo.com> wrote in message
news:Xns94BDC3D14FF451543AE@205.188.138.161...

> 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.
 
Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

Previously J. Clarke <jclarke@nospam.invalid> wrote:
> Arno Wagner wrote:

>> Previously John Smith <m@ixo.com> wrote:
>>> 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.

> 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
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus
 
Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

"J. Clarke" <jclarke@nospam.invalid> wrote in message news:c4ggeb0aeo@news1.newsguy.com
> Arno Wagner wrote:
>
> > Previously John Smith <m@ixo.com> wrote:
> > > 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.
>
> 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'.

> neither of which is a particularly desirable state of affairs.
>
>
> >
> > Arno
 
Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

"Arno Wagner" <me@privacy.net> wrote in message news:c4h8mi$2im7ae$1@ID-2964.news.uni-berlin.de
> Previously J. Clarke <jclarke@nospam.invalid> wrote:
> > Arno Wagner wrote:
>
> > > Previously John Smith <m@ixo.com> wrote:
> > > > 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.
>
> > 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,

'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
 
Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

Previously Folkert Rienstra <see_reply-to@myweb.nl> wrote:
> "Arno Wagner" <me@privacy.net> wrote in message news:c4h8mi$2im7ae$1@ID-2964.news.uni-berlin.de
>> Previously J. Clarke <jclarke@nospam.invalid> wrote:
>> > Arno Wagner wrote:
>>
>> > > Previously John Smith <m@ixo.com> wrote:
>> > > > 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.
>>
>> > 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,

> 'Clue'less.

Thanks, and the same back to you.

>> 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.

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
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus
 
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