CDB4398 Cirrus Logic Inc, CDB4398 Datasheet - Page 20

• Manufacturer Part Number: CDB4398
• Description: BOARD EVAL FOR CS4398 DAC
• Manufacturer: Cirrus Logic Inc

Specifications of CDB4398

• Number Of Dac's: 2
• Number Of Bits: 24
• Outputs And Type: 2, Differential
• Sampling Rate (per Second): 192k
• Data Interface: I²C, SPI™
• Dac Type: Voltage
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -10°C ~ 70°C
• Utilized Ic / Part: CS4398
• Description/function: Audio D/A
• Operating Supply Voltage: 5 V
• Product: Audio Modules
• For Use With/related Products: CS4398
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant
• Other names: 598-1155

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4. APPLICATIONS
4.1
4.2
4.3
Grounding and Power Supply Decoupling
As with any high resolution converter, the CS4398 requires careful attention to power supply and grounding
arrangements to optimize performance. The Typical Connection Diagram shows the recommended power
arrangement with VA, VD, VLS and VLC connected to clean supplies. Decoupling capacitors should be lo-
cated as close to the device package as possible. If desired, all supply pins may be connected to the same
supply, but the recommended decoupling capacitors should still be placed on each supply pin. The AGND
and DGND pins should be tied together with solid ground plane fill underneath the converter extending out
to the GND side of the decoupling caps for VA, VD, VREF, and FILT+. This recommended layout can be
seen in the CDB4398 evaluation board and datasheet.
Analog Output and Filtering
The Cirrus Logic application note “Design Notes for a 2-Pole Filter with Differential Input” (AN48) discusses
the second-order Butterworth filter and differential to single-ended converter topology that was implemented
on the CS4398 evaluation board, CDB4398, as seen in Figure 11.
The CS4398 does not include phase or amplitude compensation for an external filter. Therefore, the DAC
system phase and amplitude response is dependent on the external analog circuitry.
The MUTEC Outputs
The AMUTEC and BMUTEC pins have an auto-polarity detect feature. The MUTEC output pins are high
impedance at the time of reset. The external mute circuitry needs to be self-biased into an active state in
order to be muted during reset. Upon release of reset, the CS4398 detects the status of the MUTEC pins
(high or low) and then selects that state as the polarity to drive when the mutes become active. The external-
bias voltage level that the MUTEC pins see at the time of release of reset must meet the “MUTEC auto de-
tect input high/low voltage” specifications as outlined in the Digital Characteristics in Section 2.
Figure 12 shows a single example of both an active-high and an active-low mute drive circuit. In these de-
signs, the pull-up and pull-down resistors have been specifically chosen to meet the input high/low threshold
when used with the MMUN2111 and MMUN2211 internal bias resistances of 10 kΩ.
Figure 11. Recommended Output Filter
CS4398
DS568F1