TDA2050 datasheet(10/13 Pages) STMICROELECTRONICS

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ent. Fig. 17 shows this dissipable power as a

function of ambient temperature for different ther-

mal resistance.

MOUNTING INSTRUCTIONS

The power dissipated in the circuit must be re-

moved by adding an external heatsink.

Thanks

the

PENTAWATT

package, the

heatsink mounting operation is very simple, a

screw or a compression spring (clip) being suffi-

cient. Between the heatsink and the package is

better to insert a layer of silicon grease, to opti-

mize the thermal contact; no electrical isolation is

needed between the two surfaces. Fig. 18 shows

an example of heatsink.

Dimension suggestion

The following table shows the length that the

heatsink in fig. 18 must have for several values

of Ptot and Rth.

Ptot (W)

Lenght of heatsink (mm)

Rth of heatsink (

°C/W)

4.2

6.2

8.3

Figure 18: Example of heat-sink

Figure 17: Maximum Allowable Power Dissipa-

tion vs. Ambient Temperature

A.1 - MUSIC POWER CONCEPT

MUSIC POWER is (according to the IEC clauses

n.268-3 of Jan 83) the maximum power which the

amplifier is capable of producing across the rated

load resistance (regardless of non linearity) 1 sec

after the application of a sinusoidal input signal of

frequency 1 KHz.

According to this definition our method of meas-

urement comprises the following steps:

- Set the voltage supply at the maximum oper-

ating value;

- Apply a input signal in the form of a 1KHz tone

burst of 1 sec duration: the repetition period

of the signal pulses is 60 sec;

- The output voltage is measured 1 sec from the

start of the pulse;

- Increase the input voltage until the output sig-

nal shows a THD=10%;

- The music power is then V

out /RL, where

Vout is the output voltage measured in the

condition of point 4 and RL is the rated load

impedance;

The target of this method is to avoid excessive

dissipation in the amplifier.

A.2 - INSTANTANEOUS POWER

Another power measurement (MAXIMUM IN-

STANTANEOUS OUTPUT POWER) was pro-

posed by IEC in 1988 (IEC publication 268-3 sub-

clause 19.A).

We give here only a brief extract of the concept,

and a circuit useful for the measurement.

The supply voltage is set at the maximum operat-

ing value.

The test signal consists of a sinusoidal signal

whose frequency is 20 Hz, to which are added al-

ternate positive and negative pulses of 50

µs du-

ration and 500 Hz repetition rate. The amplitude

of the 20 Hz signal is chosen to drive the amplifier

to its voltage clipping limits, while the amplitude of

the pulses takes the amplifier alternately into its

current-overload limits.

APPENDIX A

TDA2050

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