Conducted Noise Immunity; Power Sequencing - Seagate ST336807FC - Cheetah 36 GB Hard Drive User Manual

[2] For +12 V, a –10% tolerance is allowed during initial spindle start but must return to ±5% before reaching
10,000 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 2.
[4] This condition occurs when the Motor Start option is enabled and the drive has not yet received a Start
Motor command.
[5] See paragraph 6.2.1, "Conducted noise immunity." Specified voltage tolerance includes ripple, noise, and
transient response.
[6] Operating condition is defined as random 8 block reads at:
255 I/Os per second (ST3300007)
251 I/Os per second (ST3146707)
254 I/Os per second (ST373207)
Current and power specified at nominal voltages. Decreasing +5 volt supply by 5% increases 5 volt cur-
rent by <0.5%. Decreasing +12 volt supply by 5% increases 12 volt current by 1.4%.
[7] During idle, the drive heads are relocated every 60 seconds to a random location within the band from
track zero to one-fourth of maximum track.
General DC power requirement notes.
1. Minimum current loading for each supply voltage is not less than 1.2% 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.
6.2.1

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 con-
nector.
+5 V = 250 mV pp from 100 Hz to 20 MHz.
+12 V = 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.
6.2.2

Power sequencing

The drive does not require power sequencing. The drive protects against inadvertent writing during power-up
and down.
Cheetah 10K.7 FC Product Manual, Rev. D 27