PA3632

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

7 of 9

www.unisonic.com.tw

QW-R107-071.b



APPLICATION INFORMATION (Cont.)

GAIN-SETTING RESISTOR RANGES

PA3632

Table 1. Recommended Resistor Values

GAIN

-1V/V

10kΩ

10kΩ

-1.5V/V

8.2kΩ

12kΩ

-2V/V

15kΩ

30kΩ

-10V/V

4.7kΩ

47kΩ

UTC PA3632 UVP OPERATION

The shutdown threshold at the UVP pin is 1.25V. The customer must use a resistor divider to obtain the shutdown

threshold and hysteresis desired for a particular application. The customer-selected thresholds can be determined as

follows:

EXTERNAL UNDERVOLTAGE DETECTION

External undervoltage detection can be used to mute/shut down the UTC PA3632 before an input device can

generate a pop.

The shutdown threshold at the UVP pin is 1.25V. The user selects a resistor divider to obtain the shutdown

threshold and hysteresis for the specific application. The thresholds can be determined as follows:

Hysteresis=5μA×R3×(R1+R2)/R2

INPUT-BLOCKING CAPACITORS

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

PA3632

. These capacitors block the dc portion of the audio source and allow the UTC PA3632 inputs to be properly

biased to provide maximum performance.

Equation 3. 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

is given.

It is recommended to use electrolytic capacitors or high-voltage-rated capacitors as input blocking capacitors to

ensure minimal variation in capacitance with input voltages. Such variation in capacitance with input voltages is

commonly seen in ceramic capacitors and can increase low-frequency audio distortion.

IN

IN

CIN

C

R

2

1

f





or

IN

IN

C

IN

R

f

2

1

C





(3)