microcontrolller startup current

[umesh49]

Hi,
I am using an Atmal micro controller for my application and it looks like it needs at least 15mA current during startup.
If it does not get supplied this current, it VCC gets latched to 1.45V. When it gets 15mA supplied for atleast 5msec then it came up and let the VCC go to regulator output level of 3V and current consumption came to 1mA.
Is any body have experience with it.

Regards,
Umesh

 

[dick_freebird]

This is common with CMOS digital circuits, to have a "hump"
in supply current right about VT(N)+VT(P). Worse, if any
input is floating or uncontrolled (and, inputs from other co-
located / co-powered CMOS sources can expect to be also
compromised - then you have many input buffers put linear
to draw power big time).

You should take a look at uC reset resources, make sure at
least that the reset pin assumes a proper reset state and
stays in it until power is within spec.

If you cannot depend on the uC to play nice, you may have
to apply some explicit power management to it - like a Vdd
switch that is only enabled when main Vdd > 2.5V, or some
such scheme, and depend on the main filter to be stiff enough
to ride out the "startup surge".