TPA0223

2-W MONO AUDIO POWER AMPLIFIER

WITH HEADPHONE DRIVE

SLOS277C – JANUARY 2000 – REVISED NOVEMBER 2002

11

POST OFFICE BOX 655303

APPLICATION INFORMATION

gain setting via input resistance

The gain of the input stage is set by the user-selected input resistor and a 50-k

Ω internal feedback resistor.

However, the power stage is internally configured with a gain of –1.25 V/V in SE mode, and –2.5 V/V in BTL

the overall gain can be calculated using equations (1) and (2).

(1)

A

V +

–125 k

W

R

I

(BTL)

(2)

A

V +

–62.5 k

W

R

I

(SE)

The –3 dB frequency can be calculated using equation 3:

(3)

ƒ

–3dB +

1

2

p R

I

C

i

If the filter must be more accurate, the value of the capacitor should be increased while the value of the resistor

to ground should be decreased. In addition, the order of the filter could be increased.

high-pass filter with the corner frequency determined in equation 4.

f

1

2

pR

I

C

i

–3 dB

fc

(4)

Equation 2 is reconfigured as equation 5.

C

i +

1

2

pR

I

fc

(5)

feedback network to the load. This leakage current creates a dc offset voltage at the input to the amplifier that

reduces useful headroom, especially in high gain applications. For this reason a low-leakage tantalum or

ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor

than the source dc level. Note that it is important to confirm the capacitor polarity in the application.