• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 63 subscribers
  • Views 651 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

Original question:

LM5170EVM-BIDIR: Question related to ISETA command Voltage

LM5170EVM-BIDIR: Board wont work with LV-Port I/p as 48V in Boost mode

Vijay Gohil12
Intellectual 465 points
Part Number: LM5170EVM-BIDIR

Dear Ti,

  I am using the LM5170EVM-BIDIR as Boost mode see below attached Picture for Jumper settings using on board Voltage Loop for 50.5V O/p since i have not connected any O/p Battery at HV-Port and just connected a small load of 540Ohms i have shorted the circuit breaker at bottom 2 pads and connected Jumper J3 too:

Now when i provide LV-Port as 12V i get o/p as 50.5V but keeping all settings same when i provide 48V at Lv-Port i just get O/p as (I/p V - 0.7V) = 47.3V instead of 50.5V. Can you explain what have i done wrong? I have also changed resistor Rovpb to 24K from 54.9K to accept I/p 48V as input to LV-Port but still it is not working. Deeply awaiting your reply.

Regards!

  • 0
    TI__Mastermind 21720 points
    Hi Vijay,

    What is the maximum voltage that you see the output voltage regulate properly?

    Please be aware that this board was not designed to operate at 48V on the low voltage side. Components like D3 might be causing the issue. This zener diode is going to try to clamp the LV port to 36V. Please remove this diode.

    Please also remove jumper J35. When the input voltage is 48V pin 6 of U2 is above the absolute maximum voltage rating. This might be causing the operational amplifier to operate in correctly.

    Thanks,

    Garrett
  • 0 in reply to Garrett Roecker
    Intellectual 465 points

    Dear Garrett,

     1.> My O/p voltage i get is 47.52V when I/p voltage is 48.02V (Even with D3 diode attached.) this is very steady even on oscilloscope. 

     2.> For D3, i just tried to connect series Amp meter in Input LV port providing 48V to check current going through D3 with no load at O/P it had a initial surge of 2A-2.5A  for <1 sec and later dropped to 0.5A  (maybe charged the current for capacitor) and reducing slowly even more slowly. Assuming I/p loss of around 0.5A maximum it still maintains 48V as I/p and not dropping to 36V. Also the Clamping Voltage for D3 is 58.1V as per datasheet. Still if you insist we can remove the Diode. See attached File below:

     3.> Please clarify properly when you say that this card was design for LV port 36 only. See attached File for TI below shows operating voltage of LV port as 3V to 48V. It clearly stats "Operating Voltage" and not "Maximum Voltage". Please See TI User Guide Attached Below:

     

      As per My design is concerned we need to use this card as Boost Mode only so i have removed (desoldered) the Diode D9 and not used Jumper J35 to avoid any problems of Buck error amp overriding boost error amp.

      Kindly provide me some solution this has to work since i have got 2 cards Purchased specially to work as boost for 12V to 48V complete range to get fix O/p of 50.5V. Also I'm trying to maintain a Constant Current using a external Circuit as suggested by you in my other post(still your reply pending in that post Click here to reply to that post too). Deeply awaiting your reply.