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SSD power: Is it using 3.3v or not?

A Molex connector for an IDE HDD supplies 12v and 5v. The SATA connectors for SATA HDDs and SSDs have 12v, 5v, and 3.3v. But I see SSDs and SATA HDDs running on Molex-to-Sata dongles like this: http://www.newegg.com/Product/Product.aspx?Item=N82E16812186163

Do these things actively step down one of the inputs to 3.3v (yeah, right), or just not supply 3.3v? And if there is no 3.3v, why do the SATA drives work? Do they not actually draw from the 3.3v? Do they step down from the 5v if the 3.3v is not present?

A minor point, but it's driving me nuts. Why do devices that require a connector with a 3.3v input work without 3.3v? Is it that the spec calls for 3.3v but all of the SSDs ever made only use the 5v input? Inquiring minds want to know.
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  1. Best answer
    Some of the newer 1.8" SSDs use the 3.3 Volts, But to the best of my knowledge all 2 1/2 in SSDs and HDDs use the 5 Volts.

    the Molex -> SATA adptors ONLY provide the +5 and +12V. and can NOT be used on the 1.8" 3.3 V SSDs.

    enclosures for 2 1/2 in SSDs/HDDs use the +5 V (USB supplied power) which is applied directly to the SSD/HDD.

    Internally the 2 1/2" SSD could be either +5V or +3.3 V. But if 3.3 V would reqire a converter circuit to step the +5 down to +3.3 V.

    For the 3.3 V 1.8" SSDs a special encloser would be required to step 5V -> 3.3V

    For direct connection to sata Power connector, this is not a problem as the correct pin suppling the voltage is mapped internally. Ie with a 5V SSD ONLY the +5 v and return are mapped, the 3.3 V and =12 V pins are simply "open circuited" at the connector input.

    Found this
    Quote: 3) Supply 3.3 volt output for your SSD – 2.5″ hard drive bays found on laptops supply 5 volts. 1.8″ SSD devices require 3.3 volts. In order for your 1.8″ SSD to function properply, you would need to use an adapter/converter that has 3.3 volt output
    End quote.
  2. Best answer selected by WyomingKnott.
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