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LM74502: The Maximum MOSFET

Eddie Chou
Expert 5450 points
Part Number: LM74502

Hi Team,

My customer is considering use LM74502 to drive multiple MOSFET,  below are customer calculation, 

if Vcap > = 10*Ciss

1pcs         PSMN1R4-40YLD Ciss(max)=  10413pF    - > 10Ciss*1pcs = 100.413nF        use VCAP=220nF

2pcs         PSMN1R4-40YLD Ciss(max)=  10413pF    -> 10*Ciss*2pcs = 200.826nF        use VCAP=330nF

4pcs         PSMN1R4-40YLD Ciss(max)=  10413pF    -> 10*Ciss*4pcs = 401.652nF        use VCAP=470nF

what are the maximum MOSFET we can drive?

Thanks & Regards

Eddie Chou

  • 0
    TI__Guru 57737 points

    Hi Eddie Chou,

    Technically there is not limit on the number of parallel FETs the LM74502-Q1 as long as the charge pump capacitor is sized appropriately. Considering the fixed gate source current and sink current strength of LM74502-Q1, Increasing the number of FETs in parallel increases Ciss and hence there will be a slight increase in the Turn ON and Turn OFF time.