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LMH13000RQEEVM: Connection issue

Brian
Prodigy 20 points

Part Number: LMH13000RQEEVM
Other Parts Discussed in Thread: LMH13000, TIDA-060025, MSP430F5529

Hi, 

I am currently working on the design that is similar to the TIDA-060025 using the LMH13000 EVM as the laser driver. I wired a laser diode to J3 pins of the driver, connected power supply (5V) to J_VLD and J_GND to ground. However, I couldn't get the laser diode to work at all. 
Also, I am not sure on how to use the MSP430F5529 LP to control the driver.

I am very new to working with pcb and evm so any guidance and advice are appreciated.


  • 0
    TI__Expert 4070 points

    Brian,

    There are few step you need to follow to make it work after you connect the laser at J3:-

    1. Power the EVM with supply at J_VDD in range of 3V to 5.5V. This power the LMH13000 ic and generate some bias needed for the device to work.

    2. Supply the laser voltage at VLD, the voltage level depends on the laser diode forward voltage drop (Vf)

    3.You need to set the laser current by applying appropriate voltage at J_VSET (see the LMH13000 user guide for VSET to IOUT transfer function) and select the mode of operation, mode0 for <=1A of laser current and Mode1 for upto 5A of laser. This selection you can do by J_MODE_SEL jumper.

    4. Ensure the device is enabled ( short pins 2 and 3 of J_PD_SEL, this is also the default setting of the EVM when shipped)

    5, Then apply the pulse signal at the J_EP and J_EN connector. Refer to section 2.3 of the EVM user guide to know how to configure the EP and EN pin for single ended or differential LVDS pulse signal.

    Let me know if it doesnot work even after you followed these steps.

    Regards

    Anant

  • 0 in reply to Anant Sinha
    Prodigy 20 points

    Hi Anant,

    Thanks for the response. I followed the instructions but still could not get the laser to start. I wonder if it need pulse signal from the MCU LP to start the laser. 

    If that is the case, then how can I send the signal from the MSP430F5529 LP? I already shorted J1 and connect J_EP of the driver EVM to pin P1.3 and pin GND on the LP.

    Thank

  • 0 in reply to Brian
    TI__Expert 4070 points

    Hi Brian,

    Can you just probe and check if you are getting any signal at EP and EN pin or not. To turn on the current at the IOUT pin, you need EP to be atleast 100mV above EN and to turn it off, EP should be be 100mV below EN. And the common mode voltage should be in between the supply rail for pulse frequency of <10Mhz. 

    Regarding the MSP430F5529 query, I am transfering this thread to MSP team who can help you better on this.

    Regards

    Anant

  • 0 in reply to Anant Sinha
    TI__Genius 14350 points

    Hello Brian,

    Could this design guide can help you? If it can't, please describe your questions in detail and then I can send this post to our SEM team who is respobslibe for TI design issue.

    Ref. Des. Maximizing Transimpedance Bandwidth for LIDAR & ToF Applications (Rev. A)

    BR,

    Janz Bai