BUILT–IN PROTECTION SYSTEMS

LOAD DUMP VOLTAGE SURGE

The TDA2004A has a circuit which enables it to wi-

thstand a voltage pulse train, on pin 9, of the type

shown in Fig. 19.

If the supply voltage peaks to more than 40 V, then

an LC filter must be insertedbetween the supply and

pin 9, in order to assure that the pulses at pin 9 will

be held within the limits shown.

A suggested LC network is shown in Fig. 18. With

this network, a train of pulsewith amplitude up to 120

V and with of 2 ms can be applied to point A. This

type of protection is ON when the supply voltage

(pulse or DC) exceeds18 V. For this reason the ma-

ximum operating supply voltage is 18 V.

SHORT CIRCUIT (AC conditions)

The TDA2004A can withstand an accidental short-

circuit from the output to ground caused by a wrong

connection during normal working.

POLARITY INVERSION

High current (up to 10 A) can be handled by the de-

vice with no damage for a longer period than the

blow-out time of a quick 2 A fuse (normally connec-

ted in series with the supply). This feature is added

to avoid destruction, if during fitting to the car, a mi-

stake on the connection of the supply is made.

OPEN GROUND

When the ratio is the ON condition and the ground

is accidentally opened, a standard audio amplifier

will be damaged. On the TDA2004A protection dio-

des are included to avoid any damage.

INDUCTIVE LOAD

A protection diode is provided to allow use of the

TDA2004A with inductive loads.

DC VOLTAGE

The maximum operating DC voltage on the

TDA2004A is 18 V.

However the device can withstand a DC voltage up

to 28 V withno damage. This could occur during win-

ter if two batteries are series connected to crank the

engine.

THERMAL SHUT-DOWN

The presence of a thermal limiting circuit offers the

following advantages :

1) an overload on the output(even if it is permanent),

or an excessive ambient temperature can be easily

withstood.

2) the heatsink can have a smaller factor of safety

compared with that of a conventional circuit. There

is no device damage in the case of excessive jun-

The maximum allowable power dissipationdepends

upon the size of the external heatsink(i.e. its thermal

resistance) ; fig. 15 shown this dissipable power as

a function of ambient temperature for different ther-

mal resistance.

Figure 18.

Figure 19.

TDA2004A

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