OM5193H Datasheet, PDF (16/56 Pages) NXP Semiconductors – Disk drive spindle and VCM with servo controller

Philips Semiconductors
Disk drive spindle and VCM with
servo controller
Product specification
OM5193H
Reading register#1 will read the state of the 3 coils coming
from the spindle control block (ACROSS, BCROSS and
CCROSS). The 3 input lines will be in bits 0, 1, and 2.
The different waveforms are shown in Section “Spindle
driver” (see also Fig.12). Note that depending on the coil
status acquisition moment, transient states (due to the
flyback pulses) can be read.
Table 5 Writing register#1
BIT
DEFAULT
VALUE
NAME
DESCRIPTION
0
0
comA
drives COMA when in manual commutation
1
0
comB
drives COMB when in manual commutation
2
0
comC
drives COMC when in manual commutation
3
0
run/stop
0 = motor to brake-after-park mode
1 = motor spinning; VCM active
4
0
manual
0 = automatic commutation mode with run/stop = 1
1 = manual commutation mode with run/stop = 1
5
0
spindiv
0 = the internal spindle clock frequency is controlled by register#6 (11)
(bit highClock_N)
1 = an additional divider by 4 is added on the internal spindle clock
6
0
sleep_N
0 = sleep mode: low power mode, serial interface active, power stages in
brake-after-park mode
1 = fully functional mode: sleep_N has higher priority than run/stop if both are
active
7
0
−
not used
8
0
−
not used
9
1
seek/trackfw 0 = VCMIN connected to SEEKSELECT
1 = VCMIN connected to TRACKFWSELECT
10
1
−
not used
11
0
reverse break 1 = active brake control
0 = normal commutations as defined by bits above
8.3 Commutation control
The commutation logic block generates the six different
states to rotate the spindle motor. The spindle driver block
provides the BEMF zero crossing information.
The commutation block interprets the zero crossing
information and determines the commutation delay time
and the next coil state. The commutation block must take
into account the following situations:
• Start-up
• No start
• Reverse rotating
• Run
• Manual commutation.
The commutation logic keeps the motor spinning by
commutating the motor after each detected zero crossing.
It measures the time between two successive BEMF zero
crossings and then determines the next commutation.
The delay (commutation delay) between a zero crossing
and the next commutation is half the time between the two
preceding zero crossings. The commutation delay
(Comdelim) can be limited to guarantee a faster lock after
the motor has gone out of lock. A maximum commutation
delay can be set via the serial port. The time is a function
of both the external clock frequency, the individual register
prescalers and the time programmed into the registers.
Figure 7 shows a typical motor commutation timing
diagram.
1998 Nov 02
16