Figure 17 : P.C. BOARD and Components Layout of the Circuit of Figure 16 (1:1 scale)

APPLICATION SUGGESTION

The recommended values of the components are those shown on application circuit of fig. 1. Different

values can be used ; the following table can help the designer.

Component

Recommended

Value

Purpose

Larger than

Smaller than

R1, R3

1.2k

Ω

Close Loop Gain

Setting (1)

Increase of Gain

Decrease of Gain

R2, R4

18k

Ω

Decrease of Gain

Increase of Gain

R5, R6

1

Ω

Frequency Stability

Danger of Oscillation at High

Frequency with Inductive Load

C1, C2

2.2

µF

Input DC Decoupling

High Turn-on Delay

High Turn-on Pop.

Higher Low Frequency

Cut-off. Increase of Noise

C3

22

µF

Ripple Rejection

Better SVR. Increase of the

Switch-on Time

Degradation of SVR

C6, C7

220

µF

Feedback Input DC

Decoupling

C8, C9

0.1

µF

Frenquency Stability

Danger of Oscillation

C10, C11

1000

µFto

2200

µF

Output DC

Decoupling

Higher Low-frequency

Cut-off

(1) The closed loop gain must be higher than 26dB.

The presence of a thermal limiting circuit offers the

following advantages:

1) an averload on the output (even if it is

pe r m an e nt ) , o r an e xce ssi ve a mb ien t

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

reduced.

The maximum allowable power dissipation de-

pends upon the size of the external heatsink (i.e.

its thermal resistance); Figure 18 shows this dissi-

pable power as a function of ambient temperature

for different thermal resistance.

Short circuit (AC Conditions). The TDA2009A can

withstand an accidentalshort circuit from the output

and ground made by a wrong connection during

normal play operation.

BUILD-IN PROTECTION SYSTEMS

THERMAL SHUT-DOWN

TDA2009A

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