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AS3400 AS3410 AS3430 1v0

Data Sheet - D e t a i l e d D e s c r i p t i o n

8 Detailed Description

This section provides a detailed description of the device related components.

8.1 Audio Line Input

The chip features one line input. The blocks can work in mono differential or in stereo single ended mode.

In addition to the 12.5-25k

Ω input impedance, LineIn has a termination resistor of 10kΩ which is also effective during MUTE to charge

eventually given input capacitors.

8.1.1 Gain Stage

The Line In gain stage is designed to have 63 gain steps of 0.75dB with a max gain of 0dB plus MUTE.

In default, the gain will be ramped up from MUTE to 0dB during startup. There is a possibility to make the playback volume user controlled by the

VOL pin with an ADC converted VOL voltage or UP/DN buttons.

In monitor mode, the gain stage can be set to an fixed default attenuation level for reducing the loudness of the music.

Figure 12. Line Inputs

8.1.2 Parameter

Table 4. Line Input Parameter

Symbol

Parameter

Condition

Min

Typ

Max

Unit

Input Signal Level

0.6*

VBAT

VBAT

Input Impedance

0dB gain (12.5k // 10k)

5.6

kΩ

-46.5dB gain (25k // 10k)

7.2

kΩ

MUTE

10

kΩ

Input Impedance Tolerance

±30

%

Input Capacitance

5pF

Programmable Gain

-46.5

+0

dB

Gain Steps

Discrete logarithmic gain steps

0.75

dB

Gain Step Accuracy

0.5

dB

Mute Attenuation

100

dB

AGND

LINL

stereo mode

LINR

10k

10k

12.5k

k

12.5k

k

QLINR

QLINL

mute

mute

AGND

LINL

mono differential mode

LINR

10k

10k

12.5k

k

12.5k

k

QLINR

QLINL

mute

mute

AGND