[SI-LIST] : GND plane heat dissipation

Tim Parks (tparks@ferrotec.ie)
Thu, 23 Jul 1998 16:42:49 +0100

Dear all
We are designing a battery operated unit whose supply uses a Maxim 712
switching regulator. Our pass transistor and sensing resistor is getting
extremely hot (75 degrees C) along with some other key components of the
analog power supply during battery charging. They are all working within
specification but this causes the whole PCB board temperature to rise
considerably.

At present we have a single ground plane for analog and digital systems on
the board. I'm considering a separate ground plane beneath the switching
section in an attempt to isolate the high temperature from the digital
section. I'd intend routing this Analog ground plane in isolation back to
the DC input ground return.

Any advice on use of separate ground planes and heat dissipation in surface
mount devices would be greatly appreciated.

Thanks
Tim

_____________________________________________________
Tim Parks
Technical Manager
Ferrotec Ltd
Unit T9
Maple Avenue
Stillorgan Industrial Park
Stillorgan Tel: 00-353-1-2952529
Co. Dublin Fax: 00-353-1-2953625
______________________________________________________