TDA5345HT Datasheet, PDF (30/44 Pages) NXP Semiconductors – 5 V spindle & VCM driver combo

Philips Semiconductors
5 V spindle & VCM driver combo
Preliminary specification
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:
Reg3v3Enable
(from serial interface)
Reg3v3PwrUp
Enable
(46)
(34)
Vdd5
2SC4210 or
similar NPN
decoupling
cap
RegNPNBase
1.23V
800 Ω
RegSense ₍₄₇₎
3.26V
internal
BandGap
voltage
reference
2 kΩ
TempMux
SpinDigOut
PowerFault
To 3.3V ICs
5 µF
1.24 kΩ
SpinMechClock
ShockCompOut
Fig.25 3.3V linear regulator
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:
1999 June 10
30