PA2005

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

12 of 16

www.unisonic.com.tw

QW-R107-035,D

BUILT-IN PROTECTION SYSTEMS

LOAD DUMP VOLTAGE SURGE

The UTC PA2005 has a circuit which enables it to withstand a voltage pulse train, on pin9, of the type shown in

Figure 3.

If the supply voltage peaks to more than 40V, then an LC filter must be inserted between the supply and pin9, in

order to assure that the pulses at pin 9 will be held withing the limits shown.

A suggested LC network is shown in Figure 2, With this network, a train of pulses with amplitude up to 120V and

width of 2ms can be applied at point A, This type of protection is ON when the supply voltage (pulse or DC) exceeds

18V. For this reason the maximum operating supply voltage is 18V.

FROM

SUPPLY

LINE

A

L=2mH

TO PIN 9

16V

C

Figure 2

Vs(V)

40

14.4

t1

t2

t1=50ms

t2=1000ms

t

Figure 3

3000μ F

SHORT CIRCUIT (AC AND DC CONDITIONS)

The UTC PA2005 can withstand a permanent short circuit on the output for a supply voltage up to 16V.

POLARITY INVERSION

High current (up to 10A) can be handled by the device with no damage for a longer period than the blow-out time

of a quick 2A fuse (normally connected in series with the supply). This feature is added to avoid destruction, if during

fitting to the car, a mistake on the connection of the supply is made.

OPEN GROUND

When the ratio is in the ON condition and the ground is accidentally opened, a standard audio amplifier will be

damaged. On the UTC PA2005 protection diodes are included to avoid any damage.

INDUCTIVE LOAD

A protection diode is provided to allow use of the UTC PA2005 with inductive loads.

DC VOLTAGE

The maxim operating DC voltage for the UTC PA2005 is 18V.

However the device can withstand a DC voltage up to 28V with no damage. This could occur during winter 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 junction temperature; all that happens is that Po (and therefore Ptot) and Id

are reduced.

The maximum allowable power dissipation depends upon the size of the external heatsink (i.e. its thermal

resistance); Figure 4 shows the dissipation power as a function of ambient temperature for different thermal

resistance.

LOUDSPEAKER PROTECTION

The circuit offers loudspeaker protection during short circuit for one wire to ground.