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Mosfet Switching Problem

Other Parts Discussed in Thread: CSD16325Q5

 I have CSD16325Q5 mosfet samples from TI, which i want to use in my project power section. Required current is 2A. CSD16325Q5 Mosfet have 33A drain source continous current. My project drain voltage is 7.5V & gate voltage is 5V. but it failed on 1A current. I am using CSD16325Q5 for switching the MIC2152 enable pin through 555timer.

  • Aman,

    The CSD16325Q5 is an N-channel Power MOSFET. 

    This type of MOSFET turns on when the gate voltage (Pin 4) is forced above the Source Voltage (Pins 1-3).  In your above application, the gate would need to be driven above 7.5V to turn-on the MOSFET, however there is a parasitic Body dioded from Source (Pins 1-3) to Drain (Pin 5 / Thermal tab) which would pull the EN pin (U44 Pin 1) to approximately 1V below 7.5V  (Pin 1 of Adapter Header 2)

    In this application you most likely want a signal level P-channel MOSFET want a P-Channel signal MOSFET which would turn-on when the gate is pulled below the source voltage.

    TI offers 7 P-channel MOSFETs.

    http://focus.ti.com/lit/ds/symlink/csd25301w1015.pdf is likely your best solution for a single P-channel MOSFET for this application or

    http://focus.ti.com/lit/ds/symlink/csd75301w1015.pdf is a dual P-channel MOSFET that would also offer another FET if needed.