L6238S datasheet(11/31 Pages) STMICROELECTRONICS

11 / 31 page

Bemf. This resychronization can either occur

whenever Output Enable or Run/Brake is first

brought low then high.

Referring to figure 2-4, the ”Hold for Resync”

state is brought low. The controller leaves this

state and enters ”Start Resync” when Output En-

able is high.

TO START-UP

LOGIC

OVER TEMP SHUTDOWN

D95IN311

OUTPUT

ENABLE

RUN/

BRAKE

FALIGN

Figure 2.3: Watch-Dog Timer

LOAD MIN DELAY

LOAD MIN MASK***

DELAY COUNT

STATE=STATE+1

MASK COUNT

LOAD DELAY=MIN

LOAD MASK=MIN

PERIOD COUNT

DELAY COUNT*

STATE=STATE+1

MASK COUNT

CHECK FOR Zc

OUTENA=1

BEMF

DRIVERS OFF

MIN CLOCK DELAY

PERIOD STOP

D95IN312

*CLOCK DELAY=(TDLY [2:0] WHEN BEMF PERIOD <3.3ms @ 10MHz (SPEED>12.7Hz FOR 8 POLES)

BEMF: BEMF RISING WITH PNSLOPE=1 OR BEMF FALLING WITH PNSLOPE=0

BEMF: BEMF RISING WITH PNSLOPE=0 OR BEMF FALLING WITH PNSLOPE=1

** MONO=0 WHEN FREQ (BEMF)=2*FREQ(PHASE)

*** MIN MASK=192/SYS_CLK(I.E.WITH SYS_CLK=10MHz, MIN MASK=19.2

µs)

BEMF

RUN/BRK=0

BEMF

DRIVERS OFF

DRIVERS ON

LOAD DELAY=PERIOD

LOAD MASK=PERIOD

RESET PERIOD

PERIOD COUNT

DELAYH COUNT*

STATE=STATE+1

MASK COUNT

MONO=0**

BEMF

RUN

MODE

OUTENA=0

OUTENA=1

HOLD FOR RESYNC

RESYNCHRONIZATION MODE

Figure 2-4

STATE=1

DRIVERS OFF

MIN CLOCK DELAY

PERIOD STOP

DELAY STOP

MASK STOP

DRIVERS OFF

MIN CLOCK DELAY

LOAD MIN DELAY

LOAD MIN MASK

PERIOD STOP

DELAY COUNT

STATE=STATE+1

MASK COUNT

CHECK FOR Zc

DRIVERS ON

PERIOD STOP

DELAY STOP

MASK STOP

STATE=STATE+1

LOAD DELAY=MIN

LOAD MASK=MAX

PERIOD COUNT

DELAY COUNT

STATE=STATE+1

MASK COUNT

CHECK FOR Zc

BEMF

221

SYS_CLK

RUN/BRAKE=1

POR=0

FROM ANY STATE

OUTENA=1

64/FALIGN

192/FALIGN

DRIVERS ON

LOAD DELAY=PERIOD

LOAD MASK=PERIOD

RESET PERIOD

PERIOD COUNT

DELAY COUNT*

STATE=STATE+1

MASK COUNT

BEMF

D95IN310

BEMF: BEMF RISING WITH PNSLOPE=1 OR BEMF FALLING WITH PNSLOPE=0

BEMF: BEMF RISING WITH PNSLOPE=0 OR BEMF FALLING WITH PNSLOPE=1

***MIN MASK=192/SYS_CLK (I.E. WITH SYS_CLK=10MHz, MIN MASK=19.2

µs)

BEMF

RUN/BRK=0

FROM ANY STATE

Figure 2.2

L6238S

11/31

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