AS3543 datasheet(23/92 Pages) AMSCO

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AS3543 3v2

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

Figure 9. Headphone Change Gain Settings

8.4.4

Headphone Detection

When the headphone amplifier is powered down, one can detect the connection of a headset. It only work if the

headset is connected between pins HPR/HPL and HPCM. As long as the headphone amplifier is powered down,

HPCM is biased to 150mV and acting as the sense pin. There is a corresponding interrupt available to be enabled.

8.4.5

Over-current Protection

The headphone amplifier has an over-current protection (e.g. HPR/HPL is shorted). This over-current protection will

power down the headphone amplifier for a programmable time-out period (512ms, 0ms). There is a corresponding

interrupt available to be enabled.

Figure 10. Headphone Overcurrent OFF-ON Sequence

8.4.6

Ground Noise Cancelation

As separate ground input allows to connect a ground sense line direct from the dock connector ground or headphone

jack shield to make the audio output independent from PCB ground noise.

8.4.7

Power Options

To save power, especially when driving 32 Ohm loads, a reduction of the bias current is selected. For 16Ohm loads

the bias current can be increased.

8.4.8

Parameter

AVDD17=1.7, AVDD27=2.7, HPVDD = 2.7V, TA= 25

C, unless otherwise mentioned

Table 13. Headphone Output Parameter

Symbol

Parameter

Condition

Min

Typ

Max

Unit

RL_HP

Load Impedance

stereo mode

CL_HP

Load Capacitance

stereo mode

100

PHP

Nominal Output Power

RL=16 , limiter enabled

RL=32 , limiter enabled

AHP

Programmable Gain

-40.5

Gain Steps

discrete logarithmic gain steps

1.5

Gain Step Accuracy

±0.25

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