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DLP7000: Switching frequency

Part Number: DLP7000
Other Parts Discussed in Thread: DLPA200, DLP9500, DLPA2000, DLPC410, DLPLCR70EVM, DLPLCRC410EVM

Hi Team,

A customer wants to know the maximum switching frequency of the mirrors of DLP7000. Do we have this data?

Regards,

Danilo

  • Hi Team,

    The customer also wants to know if the switching frequency of the mirrors are the same for all DLP devices. 

    Regards,

    Danilo

  • Danilo,

    We need a little bit of clarification on what is being asked since the data sheet has frame rates in the DMD datasheets.

    Are they wanting to know how long it takes to transition from "on to off" and "off to on"?  

    Or do they want to know how fast they can load a row and reset it?

    As far as the transition time, the DMDs are all specified the same.

    Fizix

  • Hi Fizix,

    The customer wants to know the "on to off" and "off to on" switching times of the DMD devices.

    Regards,

    Danilo

  • Danilo,

    These are not published as such, but are on the order of 2-3 microseconds, and then are followed by a "settling time".

    If you are projecting light out of a pupil (such as in a projector, the light leaves the pupil within 1-2 microseconds.  If coming from off to on, it is about the same, but is delayed by the time it takes to come over from the "off" side.

    Are they willing to share a little more about their requirements?  If they do not want to share on a public forum you can message me privately.

    Fizix

  • Hi Fizix,

    I am the customer. Actually I would like to know how fast we can load a row and reset it? Would it be >=25us (<=40kHz)?

    Thank you.

    Xinyu

  • Hello Xinyu,

    From your question it sounds like you want to load the same row repeatedly as fast as possible.  

    First we must understand the row load time, and then the MCP (Micromirror Clocking Pulse - also sometimes called a mirror reset)

      1. Row load time is fairly short. The row cycle is 16 clocks (32 edges) long [bus width is 32 bits] so that makes 32*32=1024 pixels which is the width of the XGA DMD.  At 400 MHz 16 clocks is 40 ns.
      2. The MCP time is much longer and dominates how fast you can load and reset a row.  This is defined in the DLP7000 data sheet on page 21 as 13 μs.

    Adding these gives 13.04 μs which means the fastest you can reload and reset a given row is 1/13.04 μs = ~76,7 kHz.  According to the DLPA200 data sheet the max reset frequency for the Analog reset driver is 50 kHz.  Therefore TI cannot guarantee the DLPA200 at speeds greater than 50 kHz.

    I hope this helps.

    Fizix

  • Hi Fizix,

    Thank you for the information! So I should use DLPA200 as the driver for DLP7000?

    Xinyu

  • Xinyu,

    The DLPA200 is an integral part of the chipset and is required.

    You can try driving it faster, but TI cannot guarantee operation beyond the data sheet specs.  

    I was simply pointing out that for a single row it is the limiting factor.  

    What is your requirement?

    Fizix

  • Hi Fizix,

    Thank you. I understand that. I think 50kHz should satisfy my requirement.

    Besides, I have another question. What is major difference between the products in the DLP series?

    https://www.ti.com/dlp-chip/advanced-light-control/high-speed-visible/products.html#sort=p2439max;desc

    Do they all use DLPA200 as the driver?

    Kind Regards

    Xinyu

  • Hi Xinyu,

    The devices have different array sizes, form factors (sizes) and performance specifications. 

    In general, the smaller devices are for mobile or small footprint types of products, and the larger ones for more industrial or higher performance types of applications. This is a very general statement, so you would have to check each DMD to see what your application needs.

    Each DMD requires the use of a controller chip. We call this combination a chipset. Some chipsets with larger mirror sizes like 14um or 10um require the DLPA200 driver device to supply the voltages to the mirrors. Each DMD datasheet will let you know if a chipset requires a DLPA200 device.

    Regards,

    Matt

  • Hi Matt,

    Thanks. I will look into it.

    Kind Regards

    Xinyu

  • Hi Matt,

    By the way, can you tell me that does this "Pattern rate, binary (Max) (Hz) mean?

    Thank you very much.

    Kind Regards

    Xinyu

  • Hi Xinyu,

    Normally, display patterns for the human eye have 8-bit red, green, blue data coming to the inputs of the system. The bits are weighted differently, with the 1-bit data being the "fastest" or shortest.

    For Industrial systems, we tend to talk mostly about 1-bit or binary pattern rates. The mirror is either off or on, and the user just sends 1-bit data to the system for the "fastest" pattern rate. This is what the ~32kHz pattern rate for the DLP7000 means, or the ~23kHz pattern rate for the DLP9500.

    The DLP7000 is our fastest product when it comes to pattern rate. The array size and number of electrical pins for driving data allows the device to have this pattern rate.

    Hope this helps!

    Matt

  • Hi Matt,

    Thank you. This is very helpful. If I understand correctly, this binary pattern rates is more related to display on human eyes. In my application, I want to shot the laser on DMD and use it to control the angle of reflection beam. So as Fizix explained previously, the highest switching frequency should be limited by the max reset frequency for analog reset driver (e.g. 50kHz for DLPA200), and I don't need to worry about the binary pattern rates?

    Kind Regards

    Xinyu

  • Hi Xinyu,

    Let me see if I can help.

    The binary pattern rates are highlighted for industrial uses like I believe you are planning. The goal is to steer light as fast as possible for one frame of data, and then to move the next frame as fast as possible.

    For the DLP7000 and DLP9500 DMDs, the binary pattern rates shown in the table you had are indeed the maximum pattern rates that the user can achieve. 

    We have to remember that the chipset works together: the DMD, the controller, and the driver device. The DLPA2000 was designed to support many different devices from TI, so it is designed with a large capability of 50kHz. However, the number of pins on a DMD, the array size, and then the board design choices all will go into the maximum performance achievable from one chipset combinaton.

    For Display applications for the human eye, a common frequency would be 120Hz and 24-bit (RGB) data coming in to the system.

    Hope this helps.

    Matt

  • Hi Matt,

    Thank you for your response. I don't want to use DMD as light projector to display on human eye. I only want to use it to steer the angle of light. For the fastest rate that we can change the angle of the mirrors, is it equal to the maximum binary pattern rates?

    Kind Regards

    Xinyu

  • Xinyu,

    Yes, you are correct. Changing the position of the mirrors at the maximum frequency is the "maximum binary rate."

    Regards,

    Matt

  • Hi Matt,

    Thanks! That answers my question!

    I should use DLP7000 along with DLPA200. Anything else I should purchase?

    Kind Regards

    Xinyu

  • Xinyu,

    You will need a controller: the DLPC410. 

    You can buy the individual components, or you can buy the components mounted on printed circuit boards. We have evaluation modules that you can review and purchase if you like from ti.com. They are part of the Discovery 4100 platform as shown from this link: https://www.ti.com/tool/DLPD4X00KIT.

    The DLP7000 is part of the DLPLCR70EVM, and the DLPA200 and DLPC410 devices are on the DLPLCRC410EVM.

    Regards,

    Matt

  • Hi Matt,

    Thank you so much! Since we probably don't want to design the PCB layout by ourselves, we would consider purchase the evaluation board.

    Kind Regards

    Xinyu