SLAS997B March 2014 – January 2015 TPA6166A2
PRODUCTION DATA.
The TPA6166A2 has two power-supply domains, VDD and MICVDD. The TPA6166A2 allows VDD and MICVDD supplies to come up in any order. The Internal circuit of the TPA6166A2 has diodes between VDD and MICVDD supply domain, which are reversed bias during normal operation. If MICVDD voltage is less than VDD, these diodes can get forward bias and drive MICVDD. If the application requires that the MICVDD terminal not be driven in such a condition, an external switch on MICVDD can be used. I2C read/write and the accessory-detection algorithm is disabled until both VDD and MICVDD supplies are up. During operation, if the MICVDD supply goes below its normal operating voltage, the control-register contents are still preserved. Once the supply comes up again, the accessory detection algorithm runs again to ensure the correct state. If the MICVDD supply is not powered up, the SDA line can be clamped by TPA6166A2. This is due to the internal ESD protection structure on SDA being biased based on MICVDD.
The TPA6166A2 requires adequate power supply decoupling to ensure that output noise and total harmonic distortion (THD) remain low. Use quality low equivalent-series-resistance (ESR) ceramic capacitors (X5R material or better is required for best performance). Place a 1-μF capacitor within 5 mm of the VDD and MICVDD terminal. Reducing the distance between the decoupling capacitor and VDD/MICVDD minimizes parasitic inductance and resistance, improving TPA6166A2 supply rejection performance. Use 0402 or smaller size capacitors if possible. Ensure that the ground connection of each of the capacitors has a minimum-length return path to the device. Failure to properly decouple the TPA6166A2 may degrade audio or EMC performance.