• State Resolved
  • Replies 3 replies
  • Subscribers 47 subscribers
  • Views 101 views
  • Users 0 members are here
Support feedback
Options
Options
Related

Original question:

TLV4111: High current linear drive

ALM2402-Q1: Boosting output current

David Pfaltzgraff
Expert 2475 points
Part Number: ALM2402-Q1


Tool/software:

This is a follow-up question for Jacob who helped me get this far...

The circuit you provided does work as intended when there's no load. However, it does not provide enough current to get the DC-DC converter running. Although the spec for the G60 supply says that it should start at about 0.7V and run at 175 mA with no load. The output of the ALM2402 goes as high as about 0.8 V and stays there in spite of the input. The DC-DC converter outputs nothing.

Analog is not my strong area, so I was wondering if you could provide a voltage follower type circuit that would give higher currents. Remember that one amp only supplies current while the other sinks it.

Thanks for any pointers, Dave

  • +1
    TI__Genius 15286 points

    Hey Dave, 

    Hope you are doing well!

    I am happy to hear that the circuit works with no load, but it would certainly be better if all was working right off the bat Disappointed

    I am interested to understand what may be causing this to not function.

    1. If the circuit is working with no load, yet failing with the DC-DC converter, my immediate thought is to better understand where this current could be going.  If you have an ammeter, it may be helpful to quickly verify that the Iq of the module makes sense. The ALM2402-Q1 should have an ISC of around 500mA since this is bridge tied.

    If we can confirm that the current consumption is in the 500mA+ range, we can somewhat determine that the converter is unhappy.

    Alternatively, we could also place a resistor across the leads and validate that the ALM is doing it's job properly while being loaded. 

    I am still somewhat stuck on the startup of the DC-DC converter. 175mA should be relatively easy for this amplifier. Do you have a schematic of the configuration? 

    Thanks,

    Jacob

  • 0 in reply to Jacob Nogaj
    Expert 2475 points

    Hi Jacob,

    Sometimes you just need to 'talk' to someone to help focus! On reviewing your questions, I went back to the data sheet and the layout. Figuring out that I may have misunderstood the pin assignments (top view versus bottom view), I pulled the DC-DC out of the circuit and reversed the input connections. Hey, it works!

    It appears that their pin assignment drawing is wrong. I'll need to get back to them for verification.

    The rest is gravy.

    Thanks, Dave

  • 0 in reply to David Pfaltzgraff
    TI__Genius 15286 points

    Hey Dave,

    David Pfaltzgraff said:
    Sometimes you just need to 'talk' to someone to help focus!

    Couldn't agree more, I have been in many similar positions where I just need a bit of direction as for where to look .

    Happy to hear that all is working now!

    Sounds like this is less of a setup issue, and more of a pinout diagram not being consistent across the datasheet. If you make a post on the device in subject, they can be made aware of the need to correct the datasheet. 

    Feel free to reach out if anything else comes up. 

    Have a good weekend!

    Best,

    Jacob