Reduced power supplies for Cyclone IV

[Altera_Forum]

Hi, 

as listed on the website, Cyclone IV devices shall need less power supplies than former devices to reduce costs  ".. All Cyclone IV FPGAs require only two power supplies for operation, simplifying your power distribution network and saving you board costs, board space, and design time.. "  While the Cyclone II could be operated by 3.3V (I/O) and 1.2V (Core / PLL), the Cyclone III introduced the need for an additional power supply for the PLL, a 2.5V supply. To interface with 3V3 logic devices this ends in three power supplies: 3V3 for VCCIO, 1.2V for VCCINT and the (even if no PLL being used) 2.5V for PLL analog voltage VCCA.  While stating Cylcone IV to be operatable by 2 PowerSupplies, I looked into the handbook just to see the same requirements of VCCIO, VCCINT and (even with no PLL used) VCCA as for the Cyclone III.  Thus the only constellation for operation with only two power supplies is for systems with VCCINT and VCCIO both being 1.2V?  Sincerely, Carlhermann

[Altera_Forum]

The statement doesn't say less supply voltages than Cyclone III. It makes only sense for a 2.5/1.2 V design, which is possible with Cyclone III as well. The problem is however, that Altera doesn't supply AS devices for 2.5V supply up to now, so the statement is only halfway true. 

 At first look, the Cyclone IV E doesn't bring essential changes compared to Cyclone III, possibly power reduction. I didn't yet hear about prices.

[Altera_Forum]

A Cyclone III design needed to be very carefully done when using 3,3V IO due to overshot, from a first datesheet look it seems that Cyclone IV doesn't have this design pitfall.

[Altera_Forum]

--- Quote Start ---  from a first datesheet look it seems that Cyclone IV doesn't have this design pitfall  --- Quote End ---  Why do you think that? Just compare the maximum allowed overshoot during transitions specification, it's identical for both device families.

[Altera_Forum]

--- Quote Start ---   At first look, the Cyclone IV E doesn't bring essential changes compared to Cyclone III, possibly power reduction. I didn't yet hear about prices.  --- Quote End ---    Hi, on their overview-webpage  http://www.altera.com/corporate/news_room/releases/2009/products/nr-cyclone-iv.html?f=hp&k=wn1  there is a hint on estimated price as  ".. Budgetary pricing for the smallest devices, the EP4CE6 and the EP4CGX15, will start as low as $3 and $6 respectively for 250K unit quantities in 2010. .."  CU, CS

[Altera_Forum]

oops you are right.  

Both tables in the datasheets of Cyclone III and IV are identical. This means Cyclone IV designs with 3,3V IO must also be done very carefully. Or as we did with Cyclone III use max 3,0V IO and being able to use the Spansion S25FL064A0LMFI001 as EPCS device instead of the Altera EPCS64SI16N that works @ 3,0V as well as the SDRAMs.

[Altera_Forum]

With third party products, AS configuration should work also in an all-2.5v-vccio design. But they aren't qualified by Altera, you have to decide about compatibility yourself.