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LM3481-Q1: LM3481QMM/NOPB queries

Siburaj D S
Prodigy 75 points
Part Number: LM3481-Q1
Other Parts Discussed in Thread: LM3478, LM3481

Hi Team,

For the part number LM3481QMM/NOPB below things are missing in the datasheet. Please reply to below queries ASAP.

1. Overload and short circuit circuit current limit value. Is it possible to configure the values of overload and short circuit current limit ?

2. Is it possible to run this regulator in BOOST mode without using external MOSFETs ?

3. Inside the datasheet its mentioned like regulator is having internal softstart ? Can you share the value of softstart time ?

4. Application circuit for discontinuous mode of operation.

5. Is it possible to share the emission report for this component to check about the EMC aspects ?

Regards,

Siburaj D.S.

  • 0
    TI__Mastermind 42251 points

    Hi Siburaj,

    thank you for using the E2E forum.

    See my answers/comments mapped to your questions:

    1. overcurrent is detected once the voltage at the sense resistor reaches the value of V_sense
    see: 8.2.1.2.3 Programming the Output Voltage and Output Current

    2.No, this device requires an external MOSFET

    3. see datasheet: Internal Soft-Start Delay

    4. Please have a look at this report, it explains in details the difference of CCM and DCM and how to dimension the system for that:
    Under the Hood of a DC/DC Boost Converter (ti.com)

    5. EMC heavily depends on the layout and components around that. So EMC reports for a component/device does not give any valuable information.

    Best regards,

     Stefan

  • 0 in reply to Stefan Schauer
    Prodigy 75 points

    1. overcurrent is detected once the voltage at the sense resistor reaches the value of V_sense
    see: 8.2.1.2.3 Programming the Output Voltage and Output Current

    Thanks for your reply. Still I have some doubts in reply for query 1. In our application we are planning to use output voltage 10V and current limit of 1A. Can you share me the overload current limit value. Whether its same as the short circuit current limit value ?

  • 0 in reply to Siburaj D S
    TI__Mastermind 42251 points

    Hi Siburaj,

    the LM3481 has the current limit with will prevent the circuit from currents exceeding the limit set here. This limit is do avoid that e.g. the inductor and the MOSFET get to high current. This of course also limits the current which can be delivered to the output but is not intended to set a dedicated current limit of e.g. 1A average or RMS current for the output. As the current limit in the LM3478 is defined by the current sense resistor this also depends on the input voltage.

    Best regards,

     Stefan