[SOLVED] initial state of low side switch during power up

[electric1]

I have a classic low side N-channel MOSFET switch driving a relay coil. Gate is pulled down with 100k resistor. Gate is connected to AVR MCU output, which defaults to high impedance input state at power up, so its not producing any voltage at the gate. I checked the gate voltage with the scope and it stays at zero at all times during power up, no pulses of any kind, as expected.
However, during power up the relay is activated for about 50 ms and I can't explain it. Is MOSFET with gate pulled down supposed to conduct at all during initial power up? Can someone explain this to me?
Is there an easy modification to a simple low side switch circuit to prevent such initial pulse at the load?

 

[badea]

show us schematic
anyway, change pulldown resistor to 2K or 1K and at top of your code, put a clear instruction for an ouput that drives your Mos.

regards,

 

[electric1]

never mind, found the issue, very embarrassed to have missed it earlier :sad:
I have another voltage rail which is delayed during power up and I had fly-back diode across relay coil mistakenly connected to that delayed rail, which caused it to conduct while two rails had different voltages during power-up...mystery solved...