• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 3 answers
  • Subscribers 62 subscribers
  • Views 168 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

LM5146-Q1: 30A current limit support

Shuai Yuan
Intellectual 2290 points
Part Number: LM5146-Q1
Other Parts Discussed in Thread: LM5145-Q1, LM5148-Q1, LM5148

Hi Team,

Customer wants to find one DCDC BUCK chip which can be used for 30A/40A current limit monitor. Customer want to use LM5146-Q1 to limit the 30A current, the input voltage will be 54~60V, output will be fixed 48V.

Could LM5146-Q1 support this design requirement?

If not, could you please help recommend one chip which could support customer upside 30A current limit design requirements? Do we have 40A current limit solutions also?

Thanks and regards

Shuai

  • 0
    TI__Guru 57692 points

    Hi Shuai,

    It is possible to have one phase operate at 60Vin, 54Vout at 30A, but thermals needs to be carefully scrutinized. The LM5145-Q1 75V controller (sister part to the LM5146-Q1 100V) may be an option as well, as it's pin-to-pin compatible but slightly lower cost.

    Please confirm what you mean by "current limit monitor". This controller will limit the current at the programmed setpoint and enter hiccup, meaning switching will stop for a defined interval.

    --

    Tim

  • 0 in reply to Timothy Hegarty
    TI__Intellectual 2290 points

    Hi Tim,

    Current limit function is the main design requirements in this project, customer need to guarantee the charging current for battery under quite low temperature. Also they are prefer a current sense feedback more than voltage sense feedback.

    Based on that, do you have any other better solutions for this specific customer application scenario?

    Best regards

    Shuai

  • 0 in reply to Shuai Yuan
    TI__Intellectual 2290 points

    Hi Tim,

    Please let me attach the customer's system block diagram for your reference.

    Could you please help review and confirm if this structure could work?

    An Amplifier is used to sample the low side of the load to get the output current, then the ADC of the MCU will read it and then compare to the default setting current. After that, a adjusted PWM (0~5V) will be output to the Feedback pin to adjust the output current to the needed one. Finally customer wants to control the output current to be a wanted value and the voltage change accordingly can be acceptable. (Customer design this circuits to control the charging current to the load battery under extremely low temperature, kind like a BMS system about 600W)

    Another question is customer wants to know how the Max Iout 30A be designed? Why 30A is the LM5146-Q1's Max output current? Customer actually wants a higher output current like 40A - 50A in the future design. Is it ok with LM5146-Q1 if the gate driver capacity is ignored?

    Thanks and regards

    Shuai

  • 0 in reply to Shuai Yuan
    TI__Guru 57692 points

    Hi Shuai,

    30A is just an arbitrary marketing spec in the product folder, it's not really a controller limitation. Max output current is more about the power stage components and thermals. 40-50A sounds very high, however, especially with 80V FETs. I recommend two phases for that, e.g. see the LM5148 or LM5148-Q1 (80V) controller that is stackable.

    --

    Tim

  • 0 in reply to Timothy Hegarty
    TI__Guru 57692 points

    I just sent you a friend request - let's connect so I can message you directly. We also have a new controller that may be more suited for this application.