• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 64 subscribers
  • Views 1845 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.

LM10011: I am requesting a DC-DC recommendation

kang byungchur
Prodigy 150 points
Part Number: LM10011
Other Parts Discussed in Thread: LM27403, TPS40304A, TPS546C23, TPS546C20A

I had the same question on May 19, 2017.


But I have not received any reply to this day.

So I ask for help again with almost the same content today, with the same content.

I would like to find a DC-DC with a variable output voltage by receiving a feedback (or an external pin).

I am requesting a DC-DC recommendation.

-----------------------------------------------------------------------------------------------------------------------------

[The question on May 19, 2017]

A. Circuit Design Purpose
 (1) I am designing a constant current source module to be satisfied the following specifications.
       - Vin   =  DC 12V.
       - Vout =  (0.0 Vdc) to 1.8 Vdc
       - Iout  =  DC35A

 (2) The current is higher than the output voltage, so I must have use VID(LM10011).
       However, Vout of DC / DC should be changed
                       from minimum 0.XVdc (about 0.6Vdc) to maximum 1.8Vdc 
                       according to input state of FB, and current should be supplied up to 35A.

B. Operation.
 We will design based on the figure below (LM10011 datasheet).
    However, unlike the picture,
                    Vdd=5Vdc(fixed) of the LM10011 and Vin=12Vdc(fixed) of the DC/DC.

 

(1) The MCU should control the input(VIDS,VIDC,VIDB,VIDA) of LM10011(6bit)
              so that the DC/DC Vout is soft start(0.6V -> 1.8Vdc) and soft stop(1.8V -> 0.6Vdc)
   
 (2) The IDCA_OUT output of the LM10011 is input to the "FB" of the DC/DC as shown in the figure.

 (3) We will measure the output(Vout) current of DC/DC with sensor.

 (4) The MCU receives the measured current value and monitors normal operation or overcurrent status.

 (5) During the time that the LM10011 is on(about 30 minutes),
      Adjust the IDCA_OUT output of the LM10011 to maintain a constant current (approx. DC 35A).

 (6) During the "On time(about 30 minutes)" of the LM10011 ,
      the MCU must control the IDCA_OUT output of the LM10011 to maintain constant current (approx. DC 35A).

C. Inquiries
   I went to TI.com to look for "DC/DC" to match the above behavior.
   For use as a constant current source, I looked for a DC/DC variable Vout according to the DC/DC FB.
   In addition, the DC/DC had to satisfy both input and output specifications.
   So I want to use "TPS546C23".
   However, the "PMbus" of the TPS546C23 is too difficult for me.
  
   (1) If I don't use the "PMbus" of the TPS546C23, can I use the TPS546C23 as the above DC/DC?

   (2) If not, even if it bother you, please recommend a suitable model for me.
  
  
Thank you for reading this.  

  • 0
    TI__Expert 5910 points
    Kang,
    I think your initial e2e question got lost in the wrong forum. Since you do not need PMBUS for what you are proposing to do, would recommend the LM27403 or TPS40304A. Please note in your scheme you are making the dc/dc change its voltage to modify the current. Inherently the dc/dc is not a constant current source. If the change in voltage modifies the current then yes your objective is met.

    Regards,
    Mathew
  • 0
    Intellectual 540 points
    seems a bit convoluted to me. there are a number of simpler ways to adjust a regulators voltage

    a resistor from the uP D/A to the summing junction

    depending on ratios, accuracy and response requirements you can use a PWM output with an RC filter to supply the "D/A"

    a good old fashioned R/2R ladder to the summing junction, though space and placement costs might be prohibitive
  • 0 in reply to dan lafferty
    TI__Guru**** 191445 points
    TPS546C23 may be OK to support this application, the default reference is 0.6V, the voltage divider can be designed for 1.8V output, the rail may be able support 0.6V with the current from LM1011.

    Since you don't plan to use PMBUS, alternative candidate is the TPS546C20A, through VSEL/SS pin, the reference voltage and soft start time can be programmed through external resistor.

    I need to verify the 0.6V output capability.

    Other unclear spec. are 1) the speed of the transition customer expect and 2) min/max of input voltage 3) ambient temperature and thermal dissipation condition.
  • 0 in reply to JohnTucker
    Intellectual 540 points

    I am not the OP, Kang is.

    He wants a MCU controlled current source, but was jumping through all sorts of hoops when all he needs is to do is to supply an offset current to the regulator feedback divider