SLOS970B January 2018 – January 2025 TPA6404-Q1
PRODUCTION DATA
The thermal foldback (TFB) circuitry is designed to protect the TPA6404-Q1 from excessive die temperature. This can be caused by being operated beyond the recommended operating temperature or with a weaker thermal system than recommended. The TFB reduces the on die power dissipation by reducing the closed loop gain in steps of 1.0dB, when the temperature exceeds the TFB temperature specification. The gain will increase as the temperature is reduced by the same gain step. The rate of gain reduction (attack) is controlled in register 0x28 bits 2 and 3. The rate of gain increase or recovery (release) is controlled in register 0x28 bits 0 and 1. Pop free gain changes are control by enabling a zero crossing detector, which is enabled by default in register 0x28 bit 4. The zero crossing has a wait time before the gain can change. The default is 20µs and can be increased in register 0x28 bits 7 and 8. The TFB is enabled by default and can be disabled in register 0x28 bit 5.
Figure 7-6 Thermal Foldback Attack and Release