• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 2 answers
  • Subscribers 34 subscribers
  • Views 132 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Signal driver

Marvin Gasis Arcangel
Expert 8940 points
Other Parts Discussed in Thread: TLV1812, UCC27533, UCC27624

Hi Team,

A customer is looking for a device to simulate an Incremental Encoder. Would you kindly help?

They designed a board with MCU and 2 output signal A and B (image below). These 2 signals are set up with a 90° offset, which is required for the detection of the encoder’s rotation. The characteristics of the 2 signals (A and B): max output current of 20mA, supply voltage from 10Vdc to 30Vdc and short circuit protected

The board is supplied with a voltage from 10Vdc to 30Vdc. There is dc/dc converter and an MCU. The voltage of the A and B signal is the same of the power supply (from 10 to 30 Vdc).

I hope this helps. Please let me know if you need more information

Regards,

Marvin

  • 0
    Guru 243180 points

    Logic devices do not go above 20 V. To translate to higher voltages, use a comparator or a gate driver.

    The TLV1812 is a dual comparator with push/pull output. Use a reference voltage of about 1.66 V at the inverting input. With an output current of 20 mA, it has quite a high voltage drop. What are the required VOL/VOH at this current?

    The UCC27533 is a gate driver with TTL-compatible inputs; you can use it as a high-voltage buffer or inverter.

    Use multiple devices to get four outputs. Both choices need current limiting at their outputs; it might be possible to use simple series resistors.

  • 0 in reply to Clemens Ladisch
    TI__Genius 11750 points

    Hi Marvin,

    I am on the gate drivers team. I agree with Clemens that UCC2753x series is a good choice. The 30V VDD is actually pretty rare among gate drivers also. The main downside to that device is that it is a single channel driver. It looks like you may want a dual-channel here. Some other options:

    • UCC27624 - very new dual channel driver, but 30V is absmax and rec max is only 26V. 
    • UCx707/9 - older drivers that support up to 40V VDD.
    • TPS281x - comes with an LDO to step down higher voltages.
    • There are also a few isolated gate drivers that support 30V VDD.

    Lastly, there are no drivers that I am aware of that monitor the output current for short circuit. There are some that monitor the FET for short circuit, but I assume that isn't what the customer is asking for here. All of these drivers have much higher than 20mA outputs, so the only option would be to limit it with external circuitry. One solution may be to use a PTC "resettable fuse" to limit the output current and provide some short-circuit protection with one device. 

    Please let me know if you have any questions.

    Thanks,

    Alex M.