Your Insight Desired Regarding SX48 Vcc Capacitors

Sens-a-Dat

I am looking for your insight/experience on whether ceramic capacitors should be utilized on all the Vcc pins for the SX48 chip.

If not all the Vcc pins are required to be connected to the 5V source, is there a concern for static charges developing on the unconnected pins which then might cause problems for the adjacent port pins?

If tantalum capacitors will be used in conjunction with the ceramic capacitors to meet power requirements, should they be used for each of the multiple Vcc pins, also?

Thank you,
Gary

Post Edited (Sens-a-Dat) : 9/11/2008 10:12:00 PM GMT

Mike Green

If possible, you should connect all the Vcc pins to a source of Vcc and should have bypass capacitors within a short distance (fractions of an inch).· If you don't connect them, the wiring on the chip has to supply the current and that has a higher resistance than PCB traces causing more internal noise on-chip.

The same sort of thing applies to multiple ground pins (Vss).· At low power (low speed clock) you can often get away with what you're doing.· It doesn't work very well at higher clock speeds and higher power needs.