TAS5421-Q1: How to handle the 49.9kohm resistors when configuring single-ended input

DY Ko

Part Number: TAS5421-Q1

Hello Audio team,

My customer will change the input configuration of TAS5421-Q1 from differential to single-ended, but asked how to handle the 49.9kohm resistors in the typical application schematic of TAS5421-Q1 datasheet when configuring single-ended input. Please comments on this question.

Best regards,
DY

over 7 years ago

0 Gregg Scott over 7 years ago

TI__Mastermind 45085 points

DY,
In this case as you have underlined, the 49.9kohm resistor on the IN_N input is shorted. It can be removed from the circuit.

0 DY Ko over 7 years ago in reply to Gregg Scott

TI__Expert 5130 points

Gregg,

As I know, the input impedance matching is for low noise operation.
But why the 49.9kohm resistor only on the IN_N input can be removed in the circuit?
Is it o.k. to remove all 49.9kohm resistors on the IN_N and IN_P in the TAS5421-Q1?

Best regards,
DY

0 Gregg Scott over 7 years ago in reply to DY Ko

TI__Mastermind 45085 points

DY,

The additional 49.9k ohm resistor is needed for a ground reference before the capacitor. Since you do not supply the circuit that is driving the input to the amplifier, I assume you need this resistor. It is not good practice to have a capacitor floating on one side.

0 DY Ko over 7 years ago in reply to Gregg Scott

TI__Expert 5130 points

Gregg,

Which one is your recommended configuration for single-end input of TAS5421-Q1 between #1 and #2 on the diagram below?

Best regards,
DY

0 Gregg Scott over 7 years ago in reply to DY Ko

TI__Mastermind 45085 points

DY,

You must use the schematic in #2. The schematic is #1 will work, but the gain structure will be incorrect and will not function well.

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TAS5421-Q1: How to handle the 49.9kohm resistors when configuring single-ended input