TLC5947: Pin Status at Power On

Alpesh Borad

Part Number: TLC5947

Hello,

I am using TLC5947DAPR in my current design.

I have connected BLABK, SCLK, SIN and XTAL signal to controller through Level Shifter and put the Pull up resistor (3.3V) on BLANK Signal in Controller Board.

At Output, I have placed Pull Up resistors (Pin#5 to 23) and connected to MOSFET through Inverter to keep the MOSFET OFF in default condition but some how when I power ON, the MOSFETs are ON for some time and then OFF.

I want to know the output pin condition of TLC5947DAPR at Power ON, here I have kept the BLANK pin High from controller board.

Kindly share the actual working condition of TLC5947DAPR at power ON i.e the status of each pins.

Please find the below Image for your reference.

Regards,

Alpesh

over 4 years ago

0 Kenneth Du over 4 years ago

TI__Genius 14295 points

Proper engineer has been assigned to look at it and will reply you soon.

0 Shawn Ding over 4 years ago

TI__Expert 3190 points

Hi, Alpesh,

Two suggestions:

1) remove the pull-up resisters on the channels(R1-R22)

2) add a pull-up resistor at a BLANK_5V to +5V

then, the problem should be solved.

Regards,

Shawn

0 Alpesh Borad over 4 years ago in reply to Shawn Ding

Intellectual 860 points

Hello Shawn,

Thanks for your reply.

I will check as per suggestion but I have one Question that As per Datasheet Out put Schematic Diagram is as per Below Image Figure 14..

As per my understanding, there should be Pull-Up resistor on R1-R22 as these are Open Drain Output because I am not connected LED on this Pin. I am using this pin to drive MOSFET.

If I am removing the Pull Up from R1-R22 then MOSFET will not be controlled through R1-R22.

Please correct if I am wrong.

Regards,

Alpesh.

0 Shawn Ding over 4 years ago in reply to Alpesh Borad

TI__Expert 3190 points

Hi Aipesh,

If you use the driver to drive the MOSFET, the pull-up resister is needed.

However, you need to increase te resistance from 1.5kohm to 10kohm or above, to make the current is smaller enough when channels ON(5V/10k=0.5mA)

Regards,

Shawn

0 Alpesh Borad over 4 years ago in reply to Shawn Ding

Intellectual 860 points

Hello Shawn,

Thanks for your prompt response.

I will update the resistor value from 1.5kohm to 10kohm and test it again as per your previous suggestion.

After testing I will share the result.

Also ask for solution if there is any issue.

Thanks again.

Regards,

Alpesh.

0 Alpesh Borad over 4 years ago in reply to Alpesh Borad

Intellectual 860 points

Hello Shawn,

I update as per your suggestion and it's work fine.

Thanks for your guidance.

Regards,

Alpesh

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TLC5947: Pin Status at Power On