1999 June 10

24

Philips Semiconductors

Preliminary specification

5 V spindle & VCM driver combo

TDA5345HT

Table 12 VcmMinus voltage during the slow retract step versus Vretract[2:0] programming (bits [2:0] in register #2):

In full power mode, VcmMinus voltage is limited to 2.8 V. When the spindle back-EMF is used as a supply (power down)

the voltage will not be so high. The loop is working in saturation mode and the retract PMOS is fully saturated.

It is possible to have a kind of “soft rising” slope on VcmMinus voltage when switching from the slow retract state

(VcmMinus voltage is small) to the full power state (VcmMinus voltage is high). An internal digital counter generates

During all the VCM ramp unload sequence, a programmable state machine is activated, clocked by the spindle

back-EMF on SpinMotA.

Table 13 Brake duration versus the T_VcmBrake[2:0] programming (bits [2:0] in register #3):

Table 14 Slow retract duration versus the T_SlowRet[5:0] programming (bits [8:3] in register #3):

Table 15 Full Power retract duration versus the T_FullPower[2:0] programming (bits [11:9] in register #3):

* Include typical waveform

VRETRACT[2:0]

VCMMINUS VOLTAGE

111

1 V

...

...

001

250 mV

000

125 mV

T_VCMBRAKE[2:0]

BRAKE DURATION

111

...

...

010

001

000

0

T_SLOWRET[5:0]

SLOW RET. DURATION

111111

...

...

000010

000001

000000

0

T_FULLPOW[2:0]

FULL POWER DURATION

111

...

...

010

001

000

0