TPA2006D1: Pull-Down Resistor Value inside of /Shurdown Pin

Hi Sakai-san,

I don't think this is tested so max/min data is most likely not available, although I'll still check if this or the resistor tolerance is available somwhere.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

Dear, Ivan-san. 

Thank you so much for your kindly reply & sorry to ask you about this kind of matter. 

I was working a semiconductor company before, then tasking with a designer. 

The designer said "The resistor absolute tolerance +- 20% to +- 30% will be a

limitation on the semiconductor process, the other side, the relative tolerant will be

so better". 

Could you agree with above tolerance +- 20% to +- 30%?

Best Regards, 

H. Sakai

Hi Sakai-san,

I think that would be a good estimation given the IC process.
I'll try to confirm or get relative tolerance from our team.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

Dear, Ivan-san. 

Thank you so much for your valuable comment. 

BTW, My customer is facing TPA2006D1 malfunction(shutdown) issue under

ESD testing. They input PWM signal, but it become DC at IN+ & IN-. 

The symptom can be solved to add 100kOHM series resistor on /SHUTDOWN. 

The issue seems to influence to the cable length for Speaker. 

Please let us know the solution under ESD or Immunity testing if you had an

experience to face such trouble before. 

Best Regards, 

H. Sakai

Sakai-san,

I think 20-30% tolerance is a good estimate for worst case.

Do you have schematics you can share of the circuit before and after fixing the issue?
If input signal is PWM there must be a Low-Pass filter at the amplifiers input.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

Dear, Ivan-san. 

Thank you so much for your kindly reply. 

The output impedance issue has been fixed, so they proceeded to next step. 

LPF will be located input because PWM signal input. So IN+/IN- signal should be

DCX. Sorry!!

Now, they are facing the malfunction under ESD test issue on /SHUTDOWN

or OUT+/OUT-.

Please let me know the related information if you faced past time. 

PS)

Regarding the tolerance, Is it both + & - or just only + side?

Best Regards, 

H. Sakai

Sakai-san,

I can't find previous reports of issues with TPA2006D1 during ESD tests. For the outputs perhaps adding a filter could help to prevent ESD.

The tolerance is bot + and -.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

Dear, Ivan-san. 

Thank you so much for your reply. 

The customer is requiring to explain the reason why the series 100kohm resistor with typ.300kohm

pull-down resistor can be improved the malfunction under ESD or noise immunity testings. 

I tried to consider & find out following scenario against that, but just my guess. 

1. There is the Ramp generator circuit inside of /SHUTDOWN pin. 

    The circuit creates the ramp signal for the OUT+ & OUT- duty control. 

2. To put 100kohm series resistor with typ. 300kohm pull-down resistor, the base bias voltage, also

   the peak will be decreased. 

3. The above voltage decreasing is acting to avoid the influence for malfunction under ESD or 

   noise immunity testings. 

Again, these are just my guess. Please give your advice one more time. 

Best Regards, 

H. Sakai

Sakai-san,

I'll discuss this with our systems team, they might have a better idea about the internals of the device. Although they answer may take some time, I'll keep you updated about it.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

Sakai-san,

I'm still waiting for feedback on this matter.
I'll keep you updated.

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

Sakai-san,

One possible explanation for the observed behavior is that external series resistor helps the internal pull-down resistor to keep the device under shutdown condition.
During ESD/noise test, is the SD pin externally pulled-up or down? or is it floating?

Best regards,
-Ivan Salazar
Applications Engineer - Low Power Audio & Actuators

Dear, Ivan-san. 

Thank you so much for all of your advice. 

The SD pin is pulled up to 3V by external device. 

They mentioned 100kohm series resistor to the SD pin is helped to improve. 

The bias to SD pin would be 2.25V, over 0.35V. 

Best Regards, 

H. Sakai