Cyclone III – VCCIO of unused banks

[Altera_Forum]

Is it possible to power down the VCCIO voltage on unused banks in Cyclone III devices? If Yes that which banks can be power down and what I must to do – leave unconnected VCCIO or connect they to GND?

[Altera_Forum]

Although not a definitive answer, my guess would be no. Your lowest power position would probably be have the VCCIO at 1.2V and have all the IO's defined as output's driving low, with no load attached. 

 Pete

[Altera_Forum]

The datasheet clarifies(under Recommended Operating Conditions, Notes to Table 2–3) 

  --- Quote Start ---  VCCIO for all I/O banks must be powered up during device operation.  --- Quote End ---   I don't expect power consumption differences for particularly I/O configurations. Personally I would rely on default input with weak pull-up.

[Altera_Forum]

Handbook writes: 

 Pg. 258, 296 > “VCCIO for all I/O banks must be powered up during device operation” Pg.174> “If the device is powered up from the power-down state, the VCCIO for all the I/O banks must be powered up to the appropriate level for the device to exit from POR.”  That is I must apply power on ALL Vccio. But!  But on pg.260 wrote > “POR monitors the VCCINT, VCCIO, and VCCA pins during power-on. … POR circuitry also ensures the VCCIO level of I/O banks 1, 6, 7, and 8 that contains configuration pins reach an acceptable level before configuration is triggered.”  That is may be sufficiently apply power on Vccio only of banks 1,6,7,8?  But on pg.174 wrote > “To begin configuration, the required voltages shown in Table 9–4 must be powered up to the appropriate voltage levels: VCCINT, VCCA, VCCIO for banks in which the configuration and jtag pins reside.”  For serial configuration modes used only banks 1 and 6 – may be sufficiently apply power only on Vccio of this banks (1 and 6)?  What is right?  Alexander

[Altera_Forum]

1. It's very likely, that the POR function doesn't depend on the applied configuration scheme. But that's something you can test, if you like to. 

 2. The above quoted statement about VCCIO required for all banks is clear and shouldn't give room for speculations.  3. If you see any particular reason for diconnecting VCIO for some banks, just try. But you can't be sure if problems in device operation are brought up.  Regards, Frank

[Altera_Forum]

Frank, thank You for replay 

 For Stratix IV allowed power down unused banks: http://www.altera.com/support/kdb/solutions/rd12172008_333.html  For MAX II it is impossible: http://www.altera.com/support/kdb/solutions/rd01172008_408.html  I have two project with Cyclone.  1. In 1-st project I use only 2 I/O banks from EP3C16. I am needs get deep power down from EP3C16 – I switch off Vccint, Vccd_pll, Vcca. VCCIO standby supply current is 0.9mA – it is good, but I want smaller and don’t install power switch at Vccio and make additional split plan. I thought don’t apply power at unused banks for decrease VCCIO standby supply current. 2. In 2-nd project I want keep config (I keep power Vccint, Vccd_pll, Vcca) but I am needs switch off power connected to Cyclone chips – therefore I thought switch off Vccio some banks.  Regards, Alexander

[Altera_Forum]

You can of course file a support request to Altera and ask the question explicitely. The problem is however, that the support guys also have to rely on the device manuals and won't contact the developer staff as long as the manuals don't turn out obviously insufficient. 

 Or do a test on your own, carefully monitoring total device power consumption. If power down of selected banks works, I won't expect large power savings anyway. But I didn't need low power features in a Cyclone project yet.  It's interesting, that Stratix IV apparently allows bankwise power down. Thanks for pointing to this information.  Regards, Frank

[Altera_Forum]

Frank, thank You 

 Regards, Alexander

[Altera_Forum]

You could also supply Vccint to the unused banks, as it is one of the voltages that you switch off.

[Altera_Forum]

--- Quote Start ---  You could also supply Vccint to the unused banks...  --- Quote End ---    Daixiwen  “Could”? Maybe “must”? “PCG-01003.pdf” states: “All VCCINT pins must be connected to 1.2 V supply.”  For “power down” mode I switch off all Vccint, Vccd_pll, Vcca. In work mode I powered all Vccint, Vccd_pll, Vcca. About Vccint – question: standby supply current is 0.9mA, I thought don’t apply power at all only for unused banks for decrease VCCIO standby current, used banks – always has 3.3V.  Regards, Alexander