please dont rip this site

SX Power Issues

On the surface it appears that the SX basically takes more power than an equivilent PIC in the same application. However...

Quarter speed clock, same MIPS

Because the SX is about 4 times faster than the PIC at the SAME clock frequency, you can run it at one forth the clock speed and get the same work done. Running at a slower speed DRASTICALLY reduces the power required. Now, on the other hand, virtual peripherals increase the amount of work the processor must do, but it depends on how many instructions it takes to implement the vp. A USART for example can be done in less than 20 instructions and at low baud rates, doesn't run all that often resulting in a negligible increase in power consumption. A USB vp might be a different story.


Other factors include matching the clock to the settings in the SX so that it is driven reliably but at the lowest possible power consumption. SXs have a LOT more settings for clock type.

Low voltage

Some pic's do low voltage and some do not. All the SX's do. Since I looked at them, Microchip has come out with a new version of the 16C57 that DOES support down to 2.5 volts....

...BUT, It will not run at anything like normal speeds at 2.5 volts and will not run at full speed at 3.3v

Vdd  Max Clock
3.0v  4 MHz
4.5v 20 MHz
2.5  40 kHz

That is 40 KILO Hertz at 2.5 volts.

I haven't checked, but I think you will find that most PICs are in the same boat.

Now, the SX28AC50 will do 32Mhz at 2.7v and 50Mhz at 3.0v AND because of the 4:1 pipeline that is the approximate equivelant of the PIC doing 128Mhz or 200Mhz.

So in the end, for most consumer applications, the SX can actually save you power.


file: /Techref/scenix/power.htm, 2KB, , updated: 2007/9/20 15:15, local time: 2024/7/19 07:43,

 ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE!

<A HREF=""> SX Power Issues</A>

After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type a nice message (short messages are blocked as spam) in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.

Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?

  PICList 2024 contributors:
o List host: MIT, Site host, Top posters @none found
- Page Editors: James Newton, David Cary, and YOU!
* Roman Black of Black Robotics donates from sales of Linistep stepper controller kits.
* Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters.
* Monthly Subscribers: Gregg Rew. on-going support is MOST appreciated!
* Contributors: Richard Seriani, Sr.

Welcome to!