TPA2028D1: Input resistance and HPF at input

Stephan P

Part Number: TPA2028D1

Hi,

I couldn't find a value for the input resistance of the TPA2028D1 in the datasheet, can you please provide a typical value? What would be the corner frequency of the high pass filter at the input formed by Cin and Rin when using differential input with 1uF caps?

Best regards,

Stephan

over 5 years ago

0 Luis Fernando Rodriguez S. over 5 years ago

TI__Guru* 84915 points

Hi, Stephan,

The input impedance depends of the configured gain. As you may see in the figure 28 from the typical characteristics section, the input impedance may be from 10kohms to 130kohms.

http://www.ti.com/lit/ds/symlink/tpa2028d1.pdf#page=11

The input capacitor must be selected according to the configured gain.

Best regards,
Luis Fernando Rodríguez S.

0 Stephan P over 5 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 220 points

Hi Luis Fernando

Thank you for your reply. So that means that depending on the gain the cutoff frequency will be between ~1.2Hz and ~16Hz?

Kind regards,

Stephan

0 Luis Fernando Rodriguez S. over 5 years ago in reply to Stephan P

TI__Guru* 84915 points

Hi, Stephan,

You are right. The cutoff frequency may vary in the range that you mentioned. It is important to select the correct capacitor value and gain in the design stage, since the high-pass filter cutoff frequency will be affected.

Best regards,
Luis Fernando Rodríguez S.

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

Audio

Audio forum

TPA2028D1: Input resistance and HPF at input