TLV320AIC3254: PGA input impedance spec

Part Number: TLV320AIC3254

Tool/software:

Hello,

What is the PGA input impedance on this device?  I am trying to determine a resistor pad than can work when connecting to this device since I will need to reduce the ADC drive by 6 dB (2 Vrms to 500 mVrms).  I am not finding a PGA input impedance specification in the datasheet.