1999 June 10

30

Philips Semiconductors

Preliminary specification

5 V spindle & VCM driver combo

TDA5345HT

3.3V linear regulator:

The Tda5345HT includes an analog amplifier suited to drive an external NPN that will supply the 3.3 V digital chips used

in the application together with the internal digital outputs (pins SpinDigOut (44), SpinMechClock (43), PowerFault

(37), ShockCompOut (52), TempMux (57)). The external pin Reg3v3PwrUp is used to enable (Reg3v3Pwr = 5 V) or

disable the regulator (Reg3v3Pwr = 0 V). When Reg3v3Pwr = 0 V, it is possible however to wake the regulator up through

the Reg3v3Enable bit (bit number 1 in register #4).

It has been designed to minimise the external components count.

Figure 25 shows the regulator diagram:

Negative supply regulator (-3 V) :

A capacitor-based negative supply regulator is also provided.

Due to process limitations, 2 external shottky diodes need to be added to the 2 external capacitors to make it work.

Figure 25 shows the regulator diagram:

Fig.25 3.3V linear regulator

RegNPNBase

(46)

Vdd5

RegSense (47)

internal

BandGap

voltage

reference

1.23V

800

Ω

1.24 k

Ω

2 k

Ω

5

µF

To 3.3V ICs

3.26V

Reg3v3PwrUp

Reg3v3Enable

(from serial interface)

Enable

(34)

2SC4210 or

similar NPN

decoupling

cap

SpinDigOut

PowerFault

SpinMechClock

ShockCompOut

TempMux