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Original question:

2N7001T: Are it suitable to as LED driver

CSD18541F5: Mosfet driver for LED

Marvin Gasis Arcangel
Genius 9705 points
Part Number: CSD18541F5

Hi Team,

A customer is asking for a MOSFET to be used as a LED driver in the circuit below. The purpose of the LED is a status indication

Will CSD18541F5 suffice? how would you calculate the resistor value encircled above?

Thank you.

Regards,

Marvin

  • 0
    TI__Mastermind 31725 points

    Hello Marvin,

    Thanks for the inquiry. The CSD18541F5 is our recommended replacement for the BSS138W shown in the schematic. The CSD18541F5 is in a 1.2mm2 Si LGA package vs 4mm2 SOT23 plastic package. TI on resistance is 65mOhm max vs 3.5Ohm for BSS138W or about ~50x lower resistance. The resistor value depends on the drop across the LED and how much current is required. R = (VCC - VF)/ILED. I would recommend that you verify the gate drive voltage >= 4.5V for the GPIO drive signals. Let me know if I can be of any further assistance.

    Best Regards,

    John Wallace

    TI FET Applications

  • 0 in reply to John Wallace1
    TI__Genius 9705 points

    Hi John,

    Thank you.

    The schematic has been updated. Would you kindly check if the schematic is correct and if they have used the correct values for the resistor? 

    LED rating is 12V @480mA i.e., Id(Drain output current)should not exceed more than 160mA. 

    Thanks again.

    Regards,

    Marvin

     

  • 0 in reply to Marvin Gasis Arcangel
    TI__Mastermind 31725 points

    Hi Marvin,

    The schematic looks OK to me. The 10kΩ pull up resistor on the gate of the FET will make it normally on and the GPIO signal must be pulled LOW to turn the FET off and it must be 12V compliant.

    Thanks,

    John