TDA2009A 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.
R1, R3 R2, R4 R5, R6
Recommended Value 1.2kΩ 18kΩ 1Ω
Input DC Decoupling
C8, C9 C10, C11
0.1µF 1000µF to 2200µF
Feedback Input DC Decoupling Frenquency Stability Output DC Decoupling
Purpose Close Loop Gain Setting (1) Frequency Stability
Larger than Increase of Gain Decrease of Gain Danger of Oscillation at High Frequency with Inductive Load High Turn-on Delay
Better SVR. Increase of the Switch-on Time
Smaller than Decrease of Gain Increase of Gain
High Turn-on Pop. Higher Low Frequency Cut-off. Increase of Noise Degradation of SVR
Danger of Oscillation Higher Low-frequency Cut-off
(1) The closed loop gain must be higher than 26dB.
BUILD-IN PROTECTION SYSTEMS THERMAL SHUT-DOWN The presence of a thermal limiting circuit offers the following advantages: 1) an averload on the output (even if it is pe rman e nt ), o r an e xce ssive 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 happens is that Po (and therefore Ptot) and Io are reduced.
The maximum allowable power dissipation depends upon the size of the external heatsink (i.e. its thermal resistance); Figure 18 shows this dissipable 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. 9/12