Functional Operations; Power Sequencing - Seagate ST506 Product Manual

3.0 Functional Operations
3.1 Power Sequencing (Figure 4.0)
DC ON
Plus 5 and
+
12 volts may be applied in any order; however,
+
12 volts
must be applied to start the spindle drive motor. A speed sense
circuit counts 512 disc revolutions before recalibrating the heads to
Track
~.
For this recalibration to occur, the step input signal must be
inactive. TRACK
~,
SEEK COMPLETE, and READY signals on the
interface will become true sequentially. The drive will not perform
read, write or seek functions until READY becomes true.
FIGURE 4.0
POWER UP SEQUENCE
I---
18 sec. Typical
DISC UP TO SPEED
(512 REVS COUNTED)
-TRACK 0
-READY
-SEEK COMPLETE
-DRIVE SELECT*
(*GATES READY, TK 0, SEEK COMPLETE)
-7-
AUTO RECAll BRA TE
I
PERIOD
~
5 sec. Maximum
~uPto16.67ms.
I
I
--:
I~ 15ms. Maximum
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