SLOS704B January 2011 – August 2015 TPA6138A2
PRODUCTION DATA.
The TPA6138A2 DirectPath headphone amplifier requires adequate power supply decoupling to ensure that output noise and total harmonic distortion (THD) remain low. Use good low equivalent-series-resistance (ESR) ceramic capacitors (X5R material or better is required for best performance). Place a 2.2 μF capacitor within 5 mm of the VDD pin. Reducing the distance between the decoupling capacitor and VDD minimizes parasitic inductance and resistance, improving TPA6138A2 supply rejection performance. Use 0402 or smaller size capacitors if possible.
For additional supply rejection, connect an additional 10 μF or higher value capacitor between VDD and ground. This will help filter lower frequency power supply noise. The high power supply rejection ratio (PSRR) of the TPA6138A2 makes the 10μF capacitor unnecessary in most applications.