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"OL": led di overload

Overload IndicatorThe lighting up of the Overload indicator identifies the introduction of distortions into the music playback. These distortions mainly depend on the output signal amplitude in relation to the value of power supply voltage (13.68 V) and secondarily on the RDSon parameter of the Power MOSFET inside the TA2024C chip. In fact, with the voltage required to operate the TA2024C, you cannot exceed the maximum electrical power the amplifier can provide. A 4Ω speaker with a power supply of 13.68 V cannot provide a power greater than the theoretical one given by the following formula:

Prms = (11.68V)² / (2*4Ω) = 17.05W

where 11.68V is the voltage drop applied to the MOSFET inside the TA2024C chip when the current is maximum. In this formula,
we made the hypothesis of a sinusoidal signal at 1kHz applied at the input of the amplifier and a RDSon of MOSFET equal to 0.342Ω.
Practically, in special conditions, lacking a sufficient dynamic, the CHIP performs a cut on the amplitude of the audio signal, producing a distortion. These distortions may be inaudible. In any case, being aware of the limits of operation of the chip leads the user to lower the sound volume, thus ensuring consistently optimal music listening: this is the reason which led to the introduction of the OL indicator.

Another function performed by this indicator is to report an accidental short circuit at the output terminals (amplifier output or speakers input). When this happens, the amplifier is muted and the OL indicator light comes on.
In this case, the amplifier must be turned off, the cause of the short circuit must be removed and the amplifier switched on again.
A similar operation also occurs when there is overheating of the TA2024C chip (>150°C), in which case you must switch off and wait for the chip's temperature to drop below 105°C before turning it on again. In our workshop, this event has never happened.