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LM3150: CSD18513Q5A

Part Number: LM3150
Other Parts Discussed in Thread: CSD18513Q5A, CSD18563Q5A

We are currently using the LM3150 to convert 24 V to 5 V and a seconden one for 24 V to 12 V. Normaly we are using the CSD18563Q5A as MOSFET 1 and 2. Unfortently this MOSFET is out of stock. Therfore we orderd the CSD18513Q5A but that one isn't working. Can you tell my why the CSD18513 isn't working with the LM3150 despite it has all the requierments as stated in the datasheet of the LM3150.

The MOSFET M1 get fried the circut is turned on. I already adjusted the RILM to the new MOSFET.

  • Hello Franziska 

    • Since the gate charge of the CSD18513 is bigger, the MOSFET temperature might be too high due to switching losses. Please increase the load gradually while checking the temperature. 
    • The BVds of the CSD18513 is 40V. Please check if any high frequency switching ringing at the SW pin. 
    • Please check BST-SW voltage is enough to fully enhance the M1 MOSFET during the start-up, especially at the minimum input voltage. 

    - Eric Lee

  • Hello Eric,

    The LM3150 is running on the lowest possible load with around 50 mA.

    I didn`t measured any peak over 25 V on the SW PIN.

    I gradualy increased the input Voltage to around 12 V. The Power supply showed a current of 500 mA and the MOSFETs got very hot.

    I also suspect that the gate charge is to high vor the LM3150 despite what is written in the data sheet. There it is statet that Qgtoal must be under 130 nC. Here it is in the worst case 118 nC. Still high but under the threshold of 130 nC.

    My problem is, that all other recomened MOSFETs for the LM3150 are out of stock or have a diffrent footprint.


  • Hello Franziska

    If you see 500mA input current at 50mA load, the excessive temperature increase might be caused by a shoot-through. Especially, please check the possibility of dV/dT turn-on since the issue started happening after changing the MOSFET.

    - Eric Lee