BUF12840: DAC OUTx Control by VS OFF/ON

hideyuki sakai

Mastermind 6250 points

Part Number: BUF12840

Dear, Sir.

My customer is considering the DAC OUTx control by VS OFF/ON.

- VSD(Digital supply) is applied always. So not related to POR.

- DAC OUTx outputs based on the internal resister setting, not 0V.

- DAC OUTx will be controlled by VS(Analog supply) OFF/ON.

So, I would like to make sure following;

1) Is it no problem for BUF12840 under this kind of usage?

2) Please let me know if you find any side-effect or concern under this kind of usage.

Sorry to distrb your job about this kind of matter, Please give your advice.

Best Regards,

H. Sakai

over 6 years ago

0 Costin Cazana over 6 years ago

TI__Expert 4940 points

Hi,

I have notified our expert regarding this topic. Please expect a response by 9/19/19.

Thanks,

Costin

0 hideyuki sakai over 5 years ago in reply to Costin Cazana

Mastermind 6250 points

Dear, Sir.

I am still waiting for your answers against previous questions.

I am hoping to get your help.

Best Regards,

H. Sakai

0 Costin Cazana over 5 years ago in reply to hideyuki sakai

TI__Expert 4940 points

Hi Sakai san,

I don't see any issue turning on/off Vout with Vs. The only issue system needs to take care:

1) Output protections since Vs power is disconnected- page 22 datasheet description

2) If the load has high capacitance and small series R is needed for stability

Regards,

Costin

0 hideyuki sakai over 5 years ago in reply to Costin Cazana

Mastermind 6250 points

Dear, Costin-san.

Thank you so much for your advice for previous question.

The customer tried to control following the previous method.

However, OUTx peak noise is observed when VS off. They set

DAC resister=all 0.

1. Is there any solution to solve this symptom?

They don't expect the cost increasing, so additional component such as

capacitor will not be accepted. Please give your advice one more time.

Best Regards,

H. Sakai

0 hideyuki sakai over 5 years ago in reply to hideyuki sakai

Mastermind 6250 points

Dear, Costin-san.

Sorry to disturb your job, again.

I am expecting to get your help one more time.

Best Regards,

H. Sakai

0 Costin Cazana over 5 years ago in reply to hideyuki sakai

TI__Expert 4940 points

Hi Sakai san,

Seems to me a firmware issue, Out0 turns off before Vs off, than back on when Vs turns off

Regards,

Costin

0 hideyuki sakai over 5 years ago in reply to Costin Cazana

Mastermind 6250 points

Dear, Costin-san.

Thank you so much for your checking & valuable advice.

Sorry again, but I would like to double-confirm.

1. What is the meaning of "Out0 turns off before Vs off"?

Does it mean that LD(Latch) = Low before Vs off?

2. The customer checked OUT0 set to 0V.

You never seen the issue even if OUT0 set to 0V.

Correct?

Best Regards,

H. Sakai

0 Costin Cazana over 5 years ago in reply to hideyuki sakai

TI__Expert 4940 points

Hi Sakai san,

I e-mailed you my answers

Regards,

Costin

0 hideyuki sakai over 5 years ago in reply to Costin Cazana

Mastermind 6250 points

Dear, Costin-san.

Thank you so much for all of your support.

You pointed out the firmware issue, before. The customer tried to check

the timing as below, However, the output peak is not improved.

My private e-mail ADRS is : hideyuki_sakai@marubun.co.jp

Please give us your advice one more time.

Best Regards,

H. Sakai

0 hideyuki sakai over 5 years ago in reply to hideyuki sakai

Mastermind 6250 points

Dear, Costin-san.

I am still waiting for your immediate contact to my private e-mail ADRS.

My private e-mail ADRS is : hideyuki_sakai@marubun.co.jp

Please help us one more time.

Best Regards,

H. Sakai

0 Costin Cazana over 5 years ago in reply to hideyuki sakai

TI__Expert 4940 points

Hi Sakai san,

I'll close this thread, since you got the e-mail last week

Regards,

Costin

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BUF12840: DAC OUTx Control by VS OFF/ON