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LM25137-Q1: Buck converter

Jake Lei
Prodigy 150 points
Part Number: LM25137-Q1
Other Parts Discussed in Thread: LM25137, LM25139-Q1, LM61495, LM25148, LMR60406-Q1, LM25139, LM5190-Q1, LM5117, LM5190

Tool/software:

Hi, 

I have used a lot of buck converters from TI for point of load condition (Fixed voltage and fixed current). 

Is there suitable power management IC that meets my requirement as below? 

Vin = 20V

Vo  = 12-15V (continously change, i.e., it can be 12V or 13V, 13.5V depending on operation mode, it will not change frequenctly)

Io = 500mA 

According to my research, I need current feedback into voltage feedback pin to maintain this condition (either through current sense from load or digital potentiometer at feedback..?). Not sure if this is correct tho. 

Would you please suggest suitable components or how to meet my requirement? 

Also, could you please suggest IC that can meet these requirements? this is more high power condition 

Vin = 20V

Vo = 12V 

Io = 10A 

Thank you 

*Please note that LM25137 is not the one I was using. Just adding as is required to add here. 

  • 0
    TI__Guru 73602 points

    Hi Jake,

    For the 12V/10A application, take a look at the LM25139-Q1 controller. Or if a commercial-grade part is preferred, the LM25148 is a candidate. Both options would use 30-40V external FETs. We have converter options as well - LM61495 10A converter is one possibility.

    For the low current application, take a look at the LMR60406-Q1.

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    Prodigy 150 points

    Hello, how would LM25139 device regulate current while output voltage is varying (12-15V)? Load will be varying continuously during the operation while consuming same amount of current. 

  • 0 in reply to Jake Lei
    TI__Guru 73602 points

    Are you sure you need a CC circuit? If so, take a look at the LM5190-Q1. Another option for CC regulation (with a conventional controller without CC functionality) is to add a shunt on the output and use an amplifier to inject into FB.

    You can regulate output voltage (CV) and adjust the setpoint as needed. What is the load here?

    --

    Tim

  • 0 in reply to Timothy Hegarty
    Prodigy 150 points

    Yes, I would like to use CC circuit. Load will be some electronics components that draws same amount of current but different voltage operation. 

    When using LM5190-Q1, is there anything that I need to be aware when designing for target variable voltage level (12 - 15)? 

    In design example from LM5190-Q, it shows only a fixed output voltage requirement. 

    If simpler approach is possible, that would be an ideal solution, but this seems to be simplest solution.

    Timothy Hegarty said:
    Another option for CC regulation (with a conventional controller without CC functionality) is to add a shunt on the output and use an amplifier to inject into FB

    Is there an example of this circuit? I've seen an example where FB pins controlled by current control DAC thus regulate output voltage. Not sure if this is same methodology 

  • 0 in reply to Jake Lei
    TI__Guru 73602 points

    Your application is a bit unusual - you will have VOUT moving up and down while regulating current? Should be fine as long as you design the circuit for that VOUT operating range. The LM5117 is another option here for CC, but the LM5190 is a newer part and preferred.

    You can do a search on our website for CC, e.g.  www.ti.com/lit/snvaa85, www.ti.com/lit/snaa137 

    --

    Tim

  • 0 in reply to Timothy Hegarty
    Prodigy 150 points

    Hi Timothy,

    I understood CC mode. As for LM5117 or LM5190, how could I target specific output voltage range for my requirement? It seems that it's showing only a fixed output voltage in the datasheet. 

  • 0 in reply to Jake Lei
    TI__Guru 73602 points

    The output voltage will adjust as needed in CC mode. Just set the CV setpoint above your Vout range (effectively a max Vout clamp).