OPT8320 ISSUE ON CONNECTING VMIX

safeer naz

Other Parts Discussed in Thread: OPT8320

HI,

WE ARE FACING A PROBLEM ANY HELP WILL BE THANKFUL:

AS PER DATA SHEET OF OPT8320 WE HAVE FOLLOWED THE INITIALIZATION SET UP ON PAGE 77.

BUT WHEN VMIX (1.8V) IS CONNECTED ,AFTER SETTING TG_EN=1 AND THERE AFTER SETTING TO REMOVE STANDBY BY WRITING 0X80 IS NOT HAPPENING.

BUT WHEN VMIX IS NOT CONNECTED WE ARE ABLE TO EXIT STANBY MODE BY WRITING 0X80 REGISTER.

WHAT WOULD BE THE REASON???????.

over 6 years ago

0 Jithin George over 6 years ago

Prodigy 190 points

Same problem here. Not able to exit standby mode when Vmix is connected.

Is there a requirement to Ramp up Vmix after exiting standby mode?

0 Jithin George over 6 years ago in reply to Jithin George

Prodigy 190 points

Can you let me know,
What is the state of your Standby input pin? Pulled High or Low?

0 Bharath Patil over 6 years ago in reply to Jithin George

TI__Intellectual 2030 points

Can you check the voltage on VMIX and other rails when you do this. VMIX supply takes a surge current of ~500mA upon startup. If the supplies can't handle it, it can cause a reset. Also, can you read back the register 0x80 after you have completed the power up programming sequence.

Regards

0 safeer naz over 6 years ago in reply to Bharath Patil

Prodigy 80 points

1) We made VMIX pin to the OPT8320 as controllable from our controller, initially we disabled VMIX and after setting initialisation process given in datasheet we enabled VMIX, OPCLK is obtained. Thereafter giving VD_IN pulse OPCLK is vanished, thereby we are not getting datas as HD is not high.

2) When VMIX is enabled at the starting, we are not able to remove STANDBY mode.

Is there a strict power sequence to be followed by programming, If any please suggest.

0 Bharath Patil over 6 years ago in reply to safeer naz

TI__Intellectual 2030 points

There is no strict supply sequencing required. Which is why my suspicion is that the power supplies might be tripping. Can you capture a waveform of device DVDD rail and VMIX rails when the power happens?

Regards

0 safeer naz over 6 years ago in reply to Bharath Patil

Prodigy 80 points

THERE IS NO POWER TRIPPING ON THE RAILS.WHAT ACTUALLY HAPPENS IS WHEN VMIX IS CONNECTED AND WHEN VD_IN PULSE FROM CONTROLLER IS GIVEN THE OPCLK IS VANISHED,CAN THERE BE PROBLEM IF ILLUMINATION IS NOT ENABLED WHEN VMIX IS CONNECTED.WHAT CAN BE THE REASON FOR THE MISSING OF OPCLK. PLEASE PROVIDE US WITH SUFFICIENT DETAILS AS WE ARE STUCK IN THIS PART ,ANY HELP WOULD BE THANKFUL.

0 Bharath Patil over 6 years ago in reply to safeer naz

TI__Intellectual 2030 points

Safeer,

Are you using the OPT8320 CDK? If not, which board are you using and is there any particularly noteworthy difference between the CDK and your board? Meanwhile, We are trying to replicate the board conditions under which this is happening.

Regards

0 Bharath Patil over 6 years ago in reply to Bharath Patil

TI__Intellectual 2030 points

Also, Are you using the slave mode or master mode? You mention that you are providing VD_IN. Is an external controller providing VD_IN?

Regards

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OPT8320 ISSUE ON CONNECTING VMIX