Hi,
We are in pre-production stage in one of our current projects and we found during the reliability test that the output power of the device changes from one to the other.
We are using the TAS5756M amp, we have done some testing but when we swapped the amps is when the major change happened.
FYI, the system is configured to deliver 25W per channel into 6 Ohms. Every single unit should deliver the same, but we found that some of them deliver 22W and some of them 27W, is there anything that we need to have a look at? Apparently, the manufacturer (as you can see below) has swapped the amps on the units that were producing 22W and 27W and the result was a swap on the power, so the unit that was producing 22 started producing 27 and vice versa, which concludes that the amp is causing this. What is the output tolerance of the amp?
Below is what I received from the factory:
Hardware:
Using below method to test on black and white units. White unit max power is 22W, Black unit max power is 27W.
1.Change the RC resistance on the power amplifier PWM to 10R 1% precision resistance The test power does not change
2. Swapped the Bluetooth module on these two units, no change on power test
- Swapped the TAS5756M on these two units, and output change follows the TAS5756M chips
Software:
1. Measure the output of the two power amplifiers. When the input is below 350mV (linear amplification area), and the input is above 350mV (DRC active area),
the power amplifier output of the two units is always different by 0.5dB~0.7dB
2. Measure the BT module I2S output of the two machines, it can be seen that the I2S audio amplitude of the two machines is the same
From the above, we considered the root cause is the TI TAS5756M
Please let me know if you need more info. Thank you.
