M4334

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

8 of 9

www.unisonic.com.tw

QW-R502-441A

APPLICATION CONSIDERATION

The M4334 is a complete low cost stereo digital-to-analog output system contains digital interpolation,

fourth-order delta-sigma digital-to-analog conversion, digital de-emphasis and analog low pass filter. The M4334

used the Δ-Σ modulation techniques is to avoid the limitations of resistive laser trimmed DAC architectures by using

an inherently linear 1-bit DAC.

The M4334 supports two modes of operation. The devices operate in Base Rate Mode (BRM) when

MCLK/LRCK is 256, 384 or 512 and in High Rate Mode (HRM) when MCLK/LRCK is 128 or 192. HRM allows input

sample rates up to 100 kHz.

The M4334 also has the de-emphasis function, the de-emphasis filter is active when the DEM/SCLK pin is low

for 5 consecutive falling edges of LRCK, but this function is available only in the internal SCLK mode.

When the M4334 is initially powered-up, the audio outputs, AOUTL and AOUTR, are clamped to AGND. After a

sh- ort delay of approximately 1000 sample periods, each output begins to ramp towards its quiescent voltage, VQ.

App- roximately 10,000 sample cycles later, the outputs reach VQ and audio output begins. This gradual voltage

ramping allows time for the external DC-blocking capacitor to charge to VQ, effectively blocking the quiescent DC

voltage.

To prevent transients at power-down, the device must first enter its power-down state. This is accomplished by

rem- oving MCLK or LRCK. When this occurs, audio output ceases and the internal output buffers are disconnected

from AOUTL and AOUTR. A soft-start current sink is substituted in place of AOUTL and AOUTR which allows the

DC-blo- cking capacitors to slowly discharge. Once this charge is dissipated, the power to the device may be turned

off, and the system is ready for the next power-on.

To prevent an audio transient at the next power-on, the DC-blocking capacitors must fully discharge before

turning off the power or exiting the power-down state. If full discharge does not occur, a transient will occur when the

audio outputs are initially clamped to AGND. The time that the device must remain in the power-down state is related

to the value of the DC-blocking capacitance.