SLFS040

– DECEMBER 1993

POST OFFICE BOX 655303

DALLAS, TEXAS 75265

25

PRINCIPLES OF OPERATION

Table 7. Spindle-Motor Operating Modes

PORT C

AUXOUT

PCLK

PADV

START

BIT 1

AUX1

BIT 10

AUX0

BIT 9

MULTIPLEXER

OUTPUT

MULTIPLEXER

OUTPUT

MULTIPLEXER

OUTPUT

DESCRIPTION

0

0

0

NHphase

Phase

NHphase

RUN MODE0

0

0

1

NHphase

AUXIN

NHphase

RUN MODE1

0

1

0

Fspn

Phase

NHphase

RUN MODE2

0

1

1

Fspn

AUXIN

NHphase

RUN MODE3

1

0

0

Fref

AUXIN

SCK

TEST MODE0 †

1

0

1

Fref

AUXIN

SCK

TEST MODE1 †

1

1

0

Fspn

AUXIN

SCK

TEST MODE2 †

1

1

1

NHphase

Phase

SCK

START MODE

† These test modes were developed for internal chip testing.

descriptions

AUXOUT:

The auxiliary logic output multiplexer

AUXIN:

The auxiliary logic input (can be used to commutate spindle)

PCLK:

The spindle-speed feedback clock (AUXIN or phase)

PADV:

The spindle phase-advance clock (back-EMF mode)

START:

Spindle start mode (from port C, bit 1, 1 = enable)

AUX0:

Option control (from port C, bit 9)

AUX1:

Option control (from port C, bit 10)

COMM:

Commutation via serial port (from port C, bit 4)

Fspn:

The once-around signal and the frequency of PCLK divided by 12 for an 8 pole motor (bit 11

on port B set low), or divided by 18 for a 12 pole motor (bit 11 on port B set high).

Fref:

The divided output of the speed-discriminator reference frequency (MTRCLK)

Phase:

The spindle-control logic output of the spindle even states (see Figure 4, SC 0,2,4)

NHphase:

No Halls phase is the back-EMF zero-crossing clock

Hphase:

Halls-phase clock from external Hall sensors

SCK:

Start clock, AUXIN ORed with COMM (from port C, bit 4)

RUN MODE 0:

Speed feedback information comes from motor commutation, AUXOUT = NHphase

RUN MODE 1:

Speed feedback information comes from AUXIN, AUXOUT = NHphase

RUN MODE 2:

Speed feedback information comes from motor commutation, AUXOUT = Fspn

RUN MODE 3:

Speed feedback information comes from AUXIN, AUXOUT = Fspn

TEST MODE 0: AUXOUT = Fref: Fref = MTRCLK/N; N = value stored in port-B reference counter

TEST MODE 1: AUXOUT = Fref: Fref = MTRCLK/(16

N); N = same as above

TEST MODE 2: AUXOUT = Fspin: Fspin = AUXIN/12 or 18 depending on number of motor poles (port B, bit 11)

START MODE:

Spindle commutation is controlled externally via AUXIN