Q: TAS5717 Info

 

A: TAS5717

In the HP not-used case,  HPVSS should be tied to GND, this can of-course be done through a 0R. But in the case where HP is being used, the resistor should be replaced with a cap (as shown in EVM schematic). 

The filter-topology used on the EVM is a 2nd order low-pass filter in MFB (Multi Feed-Back loop) configuration. An excellent resource that describes this in detail is the following TI app-note: http://www.ti.com/lit/an/sloa049b/sloa049b.pdf

 

A: TAS5717

>> Needed >>

 

1.) Tie AVDD, DVDD to prevent any sequencing issues. 

2.) Tie HPVDD to 3.3V. (Although Headphone is not used, it is best to tie HPVDD to 3.3V, to prevent unintentional forward biasing internal diode structure). As long as HP-shut down is tied low, the HPVDD will draw negligble current.

3.) Resistor Osc_res should be low tolerance resistor. (1% or lower)


>> Optional >>

5.) Head-phone inputs & outputs can be tied to GND or left floating

6.) HPVSS can be tied directly to GND

7.) Cap C67 (between CPP & CPN) can be removed. CPP can either be floating or tied to 3.3V. CPN can either be floating or tied to GND.

8.) HP-shut down can be tied to GND directly

 

 Additional Information:

1.) Should I be pulling the headphone inputs low?    {{ Can be tied low or left floating }} 

2.) Is there anything wrong with not powering the HPVDD?   {{ Could cause forward-biasing internal diode structures. Best to tie to 3,3V, and keep HP-SD low}} 

3.) Or not connectng HPVSS low  {{ HPVSS should be tied to GND, for the same reason as point#2 above) }}

4.) Do you know how much power will be consumed when both (PDN & RESET) are low?  {{ Will be similar to the case where RESET is held low}}

5.)  Inductors at the output will be changed to something smaller than what they are now. {{Comment:-- This will result in higher idle current, i.e. larger power consumption in idle mode. Just wanted to point this out since power-consumption was indicated to be a key care about.)

6.) I can cut the power off during power-off mode if necessary (trying to meet under half watt), but I have space issues and I’m a bit worried about pop-noise if I cut power.  {{Comment:-- Power-Off will most likely result in an audible pop.}}