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SEAGATE ENTERPRISE CAPACITY 3.5 HDD V4 SAS PRODUCT MANUAL, REV. A 24
[1] Measured with average reading DC ammeter. Instantaneous +12V current peaks will exceed these values. Power supply at nominal
voltage. N (number of drives tested) = 6, 35 Degrees C ambient.
[2] For +12 V, a –10% tolerance is allowed during initial spindle start but must return to ± 5% before reaching 7200 RPM. The ± 5% must
be maintained after the drive signifies that its power-up sequence has been completed and that the drive is able to accept selection
by the host initiator.
[3] See +12V current profile in Figure 1. (for 4TB models)
[4] This condition occurs after OOB and Speed Negotiation completes but before the drive has received the Notify Spinup primitive.
[5] See paragraph 6.3.1, "Conducted noise immunity." Specified voltage tolerance includes ripple, noise, and transient response.
[6] Operating condition is defined as random 8 block reads.
[7] During idle, the drive heads are relocated every 60 seconds to a random location within the band from three-quarters to maximum
track.
General DC power requirement notes.
1. Minimum current loading for each supply voltage is not less than 1.7% of the maximum operating current shown.
2. The +5V and +12V supplies should employ separate ground returns.
3. Where power is provided to multiple drives from a common supply, careful consideration for individual drive power
requirements should be noted. Where multiple units are powered on simultaneously, the peak starting current must be
available to each device.
4. Parameters, other than spindle start, are measured after a 10-minute warm up.
5. No terminator power.
6.3.1 Conducted noise immunity
Noise is specified as a periodic and random distribution of frequencies covering a band from DC to 10 MHz. Maximum allowed noise
values given below are peak-to-peak measurements and apply at the drive power connector.
6.3.2 Power sequencing
The drive does not require power sequencing. The drive protects against inadvertent writing during power-up and down.
+5v = 250 mV pp from 100 Hz to 20 MHz.
+12v = 800 mV pp from 100 Hz to 8 KHz.
450 mV pp from 8 KHz to 20 KHz.
250 mV pp from 20 KHz to 5 MHz.