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| Protection for the TPA3116D2 |
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| fabiodl:
I am building an amp based on the TPA3116D2. I read that if I forget to attach the speaker / 1 wire slips away, there's danger of the LC filter enter resonance and fry the chip/capacitors. I saw some protections done by attaching two diodes, which lock the output of the filters inside the voltage rail (+Vf). I have two questions though. With reference to this schematic http://www.ti.com/lit/ug/slou336b/slou336b.pdf Are right- and left- usually above ground? Or does the TPA3116D2 usually push right- and left- at negative voltages? The power supply can be as low as 5v. Does it mean that the chip can act as a "boost" converter? If the answer to any of these two questions is "yes", then I guess the diode protection I saw is unusable / impacts the performance (the second is less critical if the supply is high) |
| Zero999:
You need to refer to the TPA3116D2 data sheet to answer those questions. http://www.ti.com/lit/ds/symlink/tpa3116d2.pdf The output voltages from the TPA3116D2, to the speakers are always within the supply rails. Look at the internal schematic. Each output stage is simply a pair of MOSFETs, connected to either power supply rail. The only voltage, above the supply, is the gate drive to the high side N-MOSFETs. It enables the high side MOSFETs to turn fully on, connecting the output to the positive rail. The average voltage on each output will be half the supply voltage. |
| Prehistoricman:
--- Quote from: fabiodl on March 16, 2020, 11:06:13 am ---I read that if I forget to attach the speaker / 1 wire slips away, there's danger of the LC filter enter resonance and fry the chip/capacitors. --- End quote --- Personally, I wouldn't worry about it. You could add a light load (kilo-ohms) to be permanently attached if you're scared. --- Quote from: fabiodl on March 16, 2020, 11:06:13 am ---Are right- and left- usually above ground? Or does the TPA3116D2 usually push right- and left- at negative voltages? --- End quote --- All of the outputs will idle at half the supply voltage. This is known as a bridged amplifier configuration. Two single-ended amplifiers are used to drive the same load. These TI chips can usually go parallel-bridge as well, which is using the two bridged amplifiers driving the same load. --- Quote from: fabiodl on March 16, 2020, 11:06:13 am ---The power supply can be as low as 5v. Does it mean that the chip can act as a "boost" converter? --- End quote --- The opposite. Class D amplifiers are essentially buck converters. |
| fabiodl:
Thank you Zero999 and Prehistoricman, anything is clear now! |
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