AK4355 Datasheet, PDF(21/24 Page) Asahi Kasei Microsystems

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AK4355 Datasheet, PDF (21/24 Pages) Asahi Kasei Microsystems – 192kHz 24-Bit 6ch DAC for DVD-Audio

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ASAHI KASEI

[AK4355]

Digital Ground

System

Controller

Analog Ground

1 VREF

2 DZF

3 PDN

4 MCLK

5 BICK

6 SDTI1

7 SDTI2

8 SDTI3

9 LRCK

10 CSN

11 CCLK

12 CDTI

13 DVDD

14 DVSS

AVDD 28

AVSS 27

LOUT1+ 26

LOUT1- 25

AK4355 ROUT1+ 24

ROUT1- 23

LOUT2+ 22

LOUT2- 21

ROUT2+ 20

ROUT2- 19

LOUT3+ 18

LOUT3- 17

ROUT3+ 16

ROUT3- 15

Figure10. Ground Layout

Note: AVSS and DVSS must be connected to the same analog ground plane.

1. Grounding and Power Supply Decoupling

The AK4355 requires careful attention to power supply and grounding arrangements. AVDD and DVDD are usually

supplied from analog supply in system. Alternatively if AVDD and DVDD are supplied separately, the power up sequence

is not critical. AVSS and DVSS of the AK4355 must be connected to analog ground plane. System analog ground and

digital ground should be connected together near to where the supplies are brought onto the printed circuit board.

Decoupling capacitors should be near to the AK4355 as possible, with the small value ceramic capacitors being the nearest.

2. Voltage Reference Inputs

VREF sets the analog output range. VREF pin is normally connected to AVDD with a 0.1ÂµF ceramic capacitor. All signals,

especially clocks, should be kept away from the VREF pin in order to avoid unwanted coupling into the AK4355

3. Analog Outputs

The analog outputs are full -differential outputs and 0.64 x VREFH Vpp (typ) centered aroundthe internal common voltage

(about AVDD/2). The differential outputs are summed externally, VAOUT=(AOUT+)-(AOUT-) between AOUT+ and AOUT-.

If the summing gain is 1, the output range is 6.4Vpp (typ @VREFH=5V). The bias voltage of the external summing circuit is

supplied externally. The input data format is 2âs complement. The output voltage (VAOUT) is a positive full scale for 7FFFFF

(@24bit) and a negative full scale for 800000H (@24bit). The ideal VAOUT is 0V for 000000H (@24bit).

The internal switched -capacitor filter and external low pass filter attenuate the noise generated by the delta -sigma modulator

beyond the audio passband. DC offset on AOUT+/- is eliminated without AC coupling since the analog outputs are

differential. Figure 11and 12 show the example of external op-amp circuit summing the differential outputs.

MS0063-E-01

- 21 -

2002/07

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