TAS5721 datasheet(68/78 Pages) TI1

68 / 78 page

TAS5721

SLOS739A – JULY 2012 – REVISED MARCH 2016

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11 Power Supply Recommendations

The TAS5721 requires two power supplies; a low voltage 3.3 V nominal for the pins DVDD, AVDD and DRVDD

and a high power supply, 8 V to 24 V for the pin PVDD. There is no requirement for power up sequencing of low

and high power supplies, however is recommended to put /PDN pin to low before removing the low voltage

power supplies in order to protect the outputs.

11.1 DVDD and AVDD Supplies

The AVDD Supply is used to power the analog internal circuit of the device, and needs a well regulated and

filtered 3.3-V supply voltage. The DVDD Supply is used to power the digital circuitry. DVDD needs a well

regulated and filtered 3.3-V supply voltage.

11.2 PVDD Power Supply

The TAS5721 class-D audio amplifier requires adequate power supply decoupling to ensure the output total

harmonic distortion (THD) and noise is as low as possible. A good low equivalent-series-resistance (ESR)

ceramic capacitor, typically 1 µF, placed as close as possible to the device PVDD leads works best. For filtering

lower frequency noise signals, a 10µF or greater capacitor placed near the audio power amplifier is

recommended.

12 Layout

12.1 Layout Guidelines

Class-D switching edges are fast and switched currents are high so it is necessary to take care when planning

the layout of the printed circuit board. The following suggestions will help to meet audio, thermal and EMC

requirements.

•

uses the PCB for heat sinking therefore the powerPad needs to be soldered to the PCB and adequate copper

area and copper vias connecting the top, bottom and internal layers should be used.

•

Decoupling capacitors: the high-frequency decoupling capacitors should be placed as close to the supply pins

as possible; on the a 1-µF high-quality ceramic capacitor is used. Large (10

μ-F or greater) bulk power supply

decoupling capacitors should be placed near the on the PVDD supplies.

•

Keep the current loop from each of the outputs through the output inductor and the small filter cap and back

to GND as small and tight as possible. The size of this current loop determines its effectiveness as an

antenna.

•

To avoid crosstalk issues on the headphone/line driver output, it is recommended to have a wide space

between the traces of the outputs.

•

Grounding: A big common GND plane is recommended. The PVDD decoupling capacitors should connect to

GND. The TAS5721 PowerPAD should be connected to GND.

•

Output filter: remember to select inductors that can handle the high short circuit current of the device. The LC

filter should be placed close to the outputs.

The EVM product folder (http://www.ti.com/tool/tas5721evm) and User’s Guide available on www.ti.com shows

schematic, bill of material, gerber files and more detailed layout plots.

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