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DLP3030-Q1: Photodiode selection

Part Number: DLP3030-Q1

Dears,

I have some questions about Photodiode selection

1. Are there specs on Photodiode? Are there selected criteria and conditions?

2. Is there any restriction on the placement of Photodiode in the optical machine (where can it be placed)?

3. Is it possible to not use Photodiode on the DLP3030-Q1 architecture?

4. If needed. The reason why DLP3030 needs to add Photodiode?

5. Is there a meter for photodiode signal strength corresponding to brightness (R/G/B LED current), color temperature?

Many thanks & Best Wishes

Weite

E:weite.chi@ofilm.com

  • Our application experts will get back to you shortly on these topics.

  • Hi Weite,

    Please see the following document related to photodiode selection and why it is important for the system. 

    2514478_PD_App_note_RevA (1).pdf

    Thanks,

    Alex Chan

  • Hi Alex,

    There are still a few questions, please help, thanks.

    1. What is the feedback effect of the PD placed outside the shell?

    2. What is the specific feedback process for PD?

    3. What is the main contribution of PD?

    4. Is there any data provided for photodiode signal strength corresponding to brightness (R/G/B LED current), color temperature, thermal protection?

    Many thanks & Best Wishes.

    Weite

    E:weite.chi@ofilm.com

  • Hi Weite,

    Please see the following responses.

    1. For debug or analysis purposes you can have a photodiode outside your system but you would have to also be aware of stray or environmental light. Additionally you will have the system projecting light onto a surface but if your photodiode is in the way it is going to block the projection.

    2/3. Please see the following images from the document I previous sent to you.

    Additionally here is another attachment explaining how the LED Drivers work for the DLP3030Q1 display system and it discusses the use of the photodiode in more detail.

    dlpa084 (1).pdf

    4.) As the application note states, the photodiode placement can directly impact brightness so careful testing of placement in the system must be done.

    Additionally photodiode placement will be important for the whitepoint calibration of the system. The whitepoint calibration of the system will ensure correct whitepoint color matching is done across the brightness range across various temperature range. A calibration table will be generated with system settings to account for various temperatures to achieve correct brightness with good color performance. Calibration uses the photodiode so it is important that the photodiode is setup and placed correctly. We also have a temp sensor on our boards to allow the system in the field to automatically adjust to the ambient temperature to change LED intensities to balance color/brightness.

     

    In terms of thermal performance, it would be up to the customer to ensure their end system has appropriate thermal management such as heatsinks or some other cooling method like fans. If you look at the user guides for our electronics boards, they have appropriate specifications listed of temperature and electrical characteristics.

    https://www.ti.com/tool/DLP3030Q1EVM?keyMatch=DLP3030Q1EVM

    Thanks,

    Alex Chan

  • Hi Alex,

    There is another small question.

    What is the reason why Photodiode must be used on DLP3030-Q1?

    Many thanks & Best Wishes.

    Weite

  • Hi Weite,

    Please see the information from the dlpa084 application note about LED Drivers for DLP3030-Q1 Displays. We use the photodiode extensively as part of real time feedback in the system to maintain correct LED behavior. 

    Thanks,

    Alex Chan