Datasheet

2p R

2p fc

- In

DifferentialInput

InvertingInput

DRV602

+ In

- In

DRV602

SLOS572D –DECEMBER 2008–REVISED OCTOBER 2010

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Input-Blocking Capacitors

DC input-blocking capacitors are required to be added in series with the audio signal into the input pins of the

DRV602. These capacitors block the DC portion of the audio source and allow the DRV602 inputs to be properly

biased to provide maximum performance. The input blocking capacitors also limit the DC gain to 1, limiting the

DC-offset voltage at the output.

These capacitors form a high-pass filter with the input resistor, R

. The cutoff frequency is calculated using

Equation 1. For this calculation, the capacitance used is the input-blocking capacitor and the resistance is the

input resistor chosen from Table 1, then the frequency and/or capacitance can be determined when one of the

two values are given.

(1)

Using the DRV602 as 2

Order Filter

Several audio DACs used today require an external low-pass filter to remove out of band noise. This is possible

with the DRV602 as it can be used like a standard OPAMP.

Several filter topologies can be implemented both single ended and differential. In Figure 9, a Multi FeedBack -

MFB, with differential input and single ended input is shown.

An ac-coupling capacitor to remove dc-content from the source is shown, it serves to block any dc content from

the source and lowers the dc-gain to 1 helping reducing the output dc-offset to minimum.

The component values can be calculated with the help of the TI FilterPro™ program available on the TI website

at: http://focus.ti.com/docs/toolsw/folders/print/filterpro.html

Figure 9. 2

Order Active Low Pass Filter

The resistor values should have a low value for obtaining low noise, but should also have a high enough value to

get a small size ac-coupling cap. With the proposed values, 33k, 68k, 100k, a DNR of 102dB can be achieved

with a small 1mF input ac-coupling capacitor.

Product Folder Link(s): DRV602