SLOS970B January 2018 – January 2025 TPA6404-Q1
PRODUCTION DATA
The DC load diagnostics are used to verify the load is connected properly. The DC diagnostics consists of four tests: short-to-power (S2P), short-to-ground (S2G), open-load (OL), and shorted-load (SL). The S2P and S2G tests trigger if the impedance to ground or the impedance to power is below that specified in the Section 5 section. The diagnostic also detects a short to vehicle battery when the supply is boosted. The SL test has an I2C-configurable threshold depending on the expected load to be connected. Because the speakers and cable impedance connected to each channel might be different, each channel can be assigned a unique threshold value. The OL test reports if the selected channel has a load impedance greater than the limits in the Section 5 section.
The duration of DC load diagnostics can be as short as 250ms and as long as 600ms depending on any fault conditions. The time extension is due to retesting the fault conditions to reduce false positives. Additional time will be added by changing the buffer time or settling time parameters in register 0x09. Buffer time is a delay before the test starts. This is added before the S2G and S2P tests and also added before the SL and the OL tests. The Ramp time is the time that the output is ramped up and down for the SL and OL tests. The settling time is the duration of the SL and OL test.