1999 June 10

27

Philips Semiconductors

Preliminary specification

5 V spindle & VCM driver combo

TDA5345HT

The device is protected against over-temperature by the temperature shutdown circuit. When the temperature of the chip

exceeds 160

°C, the device is automatically set to a VCM retract and a spindle disable mode. It remains in this mode

until the temperature goes below 160

°C - 30 °C = 130 °C (30 °C is an internal hysteresis).

During normal operation, the signal TempMux provides either a voltage that is function of the chip temperature when

TempSelect = ‘1’ or a digital warning when TempSelect = ‘0’.

When the analog information is selected, the equation of the voltage versus the temperature is:

(18)

When the digital information is selected, you get a temperature warning on pin TempMux (57). If the internal temperature

over passes 145

°C, TempMux = ‘1’ and remains high until the temperature comes below 130 °C (see Fig.19).

IT IS STRONGLY ADVISED TO USE THE TempMux INFORMATION (analog or digital) TO GENERATE EMERGENCY

PROCEDURES INSTEAD OF WAITING FOR THE TEMPERATURE SHUT DOWN MODE TO TRIGGER. The

temperature shut down has to considered as an ultimate self-protection.

Fig.19 Temperature monitor circuitry

TempMux

TempSelect

(bit 0, reg#3)

junction thermometer

Voltage

Converter

55

Temp shut

1

0

V

TempMux

2.954

7.55 10

3

–

⋅





Temperature

°C

(

)

×

–

=

130

145

TEMPERATURE (

°C)

0

Vdd5

0