Hello, This problem has been getting on my nerves for quite some time now. First of all I'll let you know that I'm an inexperienced engineer - it's my first year in the field, so please bear with my inherent foolishness where applicable. Now to the point: I'm working on a design which uses the Altera Cyclone as a comm dispatcher/bridge/multiplexer between 3 Microchip PIC18F452, an FTDI 245 USB_to_parallel IC and an Cypress SL811HST USB host controller. The problem is the Cyclone overheats constantly (to about 85 C) from power-up. I have excluded the possibility of outputs colliding with other outputs by only soldering the FPGA to an empty PCB, suppling it with power and downloading the configuration to it and the problem is the same - it overheats whether configured or not. There is no difference in temperature between the configured and unconfigured state. I have tried all the obvious tests including short-circuit-to-ground-or-power testing of each IO pin and all are well. Also all the power pins are properly conected. One thing to know is that the PCB is designed in house by us so there may be errors there as well as this is the first version of the design. Another important observation is that the design was initialy developed on a breadboard using a Cyclone mini dev board purchased from www.devboards.de and connecting the rest by strap-wire. It worked fine without overheating with the same configuration data for the Cyclone. Please suggest any test path I should try to figure out this mess as deadlines ar pressing me quite strongly. Thanks a lot!
Cyclone device misteriously overheats
Started by ●December 13, 2004
Reply by ●December 13, 20042004-12-13
"Alex Somesan" <alex.somesan@gmail.com> wrote in message news:1102976011.748524.106200@f14g2000cwb.googlegroups.com...> Hello, > > This problem has been getting on my nerves for quite some time now. > First of all I'll let you know that I'm an inexperienced engineer - > it's my first year in the field, so please bear with my inherent > foolishness where applicable. > Now to the point: I'm working on a design which uses the Altera Cyclone > as a comm dispatcher/bridge/multiplexer between 3 Microchip PIC18F452, > an FTDI 245 USB_to_parallel IC and an Cypress SL811HST USB host > controller. The problem is the Cyclone overheats constantly (to about > 85 C) from power-up. I have excluded the possibility of outputs > colliding with other outputs by only soldering the FPGA to an empty > PCB, suppling it with power and downloading the configuration to it > and the problem is the same - it overheats whether configured or not. > There is no difference in temperature between the configured and > unconfigured state. I have tried all the obvious tests including > short-circuit-to-ground-or-power testing of each IO pin and all are > well. Also all the power pins are properly conected. One thing to know > is that the PCB is designed in house by us so there may be errors there > as well as this is the first version of the design. Another important > observation is that the design was initialy developed on a breadboard > using a Cyclone mini dev board purchased from www.devboards.de and > connecting the rest by strap-wire. It worked fine without overheating > with the same configuration data for the Cyclone. > > Please suggest any test path I should try to figure out this mess as > deadlines ar pressing me quite strongly. > > Thanks a lot! >Have you checked the power supplies with a scope? What frequency does it run at? Does it work despite its temperature? Jeroen
Reply by ●December 13, 20042004-12-13
Yes, I've checked the powe supply (3.3 V from a LM317). Look OK on the scope. Even tried powering it from de old breadboard power supply which proved reliable. It runs at 20 MHz from an oscillator device. Yes, it works despite the heat but ocasionaly freezes up (I suspect it messes up configuration RAM contents because a reconfiguration, even without cutting power, gets it working again).
Reply by ●December 13, 20042004-12-13
"Alex Somesan" <alex.somesan@gmail.com> wrote in message news:1102977576.801325.220500@c13g2000cwb.googlegroups.com...> Yes, I've checked the powe supply (3.3 V from a LM317). Look OK on the > scope. Even tried powering it from de old breadboard power supply which > proved reliable. > It runs at 20 MHz from an oscillator device. > > Yes, it works despite the heat but ocasionaly freezes up (I suspect it > messes up configuration RAM contents because a reconfiguration, even > without cutting power, gets it working again).Have you also checked the core supply of 1V5? How much ripple? Is the device properly bypassed? Can the supply deliver enough current? Especially on power up the FPGA needs more current. I don't which Cyclone you're using, but an 1C20 needs up to 1.2A at power up. Are there no floating inputs? At certain input voltages the logic can't decide on a level and it will oscillate heavily at several hunderds of MHz. Are the inputs in your logic properly synchronised? Inputs that go into a metastable state may oscillate, and the oscillation will propagate through the device. Jeroen
Reply by ●December 13, 20042004-12-13
"Alex Somesan" <alex.somesan@gmail.com> wrote in news:1102977576.801325.220500@c13g2000cwb.googlegroups.com:> Yes, I've checked the powe supply (3.3 V from a LM317). Look OK on the > scope. Even tried powering it from de old breadboard power supply which > proved reliable. > > It runs at 20 MHz from an oscillator device. > > Yes, it works despite the heat but ocasionaly freezes up (I suspect it > messes up configuration RAM contents because a reconfiguration, even > without cutting power, gets it working again). >There is a 1.5V supply as well? -- Al Clark Danville Signal Processing, Inc. -------------------------------------------------------------------- Purveyors of Fine DSP Hardware and other Cool Stuff Available at http://www.danvillesignal.com
Reply by ●December 14, 20042004-12-14
Jeroen wrote:> "Alex Somesan" <alex.somesan@gmail.com> wrote in message > news:1102977576.801325.220500@c13g2000cwb.googlegroups.com... > > Yes, I've checked the powe supply (3.3 V from a LM317). Look OK onthe> > scope. Even tried powering it from de old breadboard power supplywhich> > proved reliable. > > It runs at 20 MHz from an oscillator device. > > > > Yes, it works despite the heat but ocasionaly freezes up (I suspectit> > messes up configuration RAM contents because a reconfiguration,even> > without cutting power, gets it working again). > > Have you also checked the core supply of 1V5? How much ripple? Is thedevice> properly bypassed? Can the supply deliver enough current? Especiallyon> power up the FPGA needs more current. I don't which Cyclone you'reusing,> but an 1C20 needs up to 1.2A at power up. > > Are there no floating inputs? At certain input voltages the logiccan't> decide on a level and it will oscillate heavily at several hunderdsof MHz.> Are the inputs in your logic properly synchronised? Inputs that gointo a> metastable state may oscillate, and the oscillation will propagatethrough> the device. > > JeroenThe power supply is the same as the one used on the breadboard prototype and that one worked fine so I presume it does deliver enough current. Measured current for the whole board with all the devices mounted and the FPGA configured is around 300mA. The Cyclone is a EP1C3T144C8 which in the datasheet is speced at around 500mA at powerup. The power supply can deliver 1.5A considering the datasheet of the LM317. I scoped the power line and found around 20mV of ripple both over and under the 3V average wich sometimes fades to zero ripple. I can't recall of any 1V5 power for the core on the device pinout. The only 1V5 requirement is for the analogue part of the PLL. So as far as I know there is no separate 1V5 supply for the core. The PLL 1V5 supply is OK. I don't realy understand what you mean by floating imputs?. Almost all of the device IO pins are used on the design so there are around 6 pins left unconected on the Cyclone. What sould I do with these? Shoud they be tristated from the design software? As far as input oscillation I don't know if it is directly related to the problems as the heating occurs even when the device is the only chip soldered to the board and both in unconfigured or configured state.
Reply by ●December 14, 20042004-12-14
"Alex Somesan" <alex.somesan@gmail.com> schreef in bericht news:1103024769.952592.211250@f14g2000cwb.googlegroups.com...> Jeroen wrote: > > "Alex Somesan" <alex.somesan@gmail.com> wrote in message > > news:1102977576.801325.220500@c13g2000cwb.googlegroups.com... > > > Yes, I've checked the powe supply (3.3 V from a LM317). Look OK on > the > > > scope. Even tried powering it from de old breadboard power supply > which > > > proved reliable. > > > It runs at 20 MHz from an oscillator device. > > > > > > Yes, it works despite the heat but ocasionaly freezes up (I suspect > it > > > messes up configuration RAM contents because a reconfiguration, > even > > > without cutting power, gets it working again). > > > > Have you also checked the core supply of 1V5? How much ripple? Is the > device > > properly bypassed? Can the supply deliver enough current? Especially > on > > power up the FPGA needs more current. I don't which Cyclone you're > using, > > but an 1C20 needs up to 1.2A at power up. > > > > Are there no floating inputs? At certain input voltages the logic > can't > > decide on a level and it will oscillate heavily at several hunderds > of MHz. > > Are the inputs in your logic properly synchronised? Inputs that go > into a > > metastable state may oscillate, and the oscillation will propagate > through > > the device. > > > > Jeroen > > The power supply is the same as the one used on the breadboard > prototype and that one worked fine so I presume it does deliver enough > current. Measured current for the whole board with all the devices > mounted and the FPGA configured is around 300mA. The Cyclone is a > EP1C3T144C8 which in the datasheet is speced at around 500mA at > powerup. The power supply can deliver 1.5A considering the datasheet of > the LM317. I scoped the power line and found around 20mV of ripple both > over and under the 3V average wich sometimes fades to zero ripple. I > can't recall of any 1V5 power for the core on the device pinout. The > only 1V5 requirement is for the analogue part of the PLL. So as far as > I know there is no separate 1V5 supply for the core. The PLL 1V5 supply > is OK.So you have all pins called VCCint tied to 3V3??? Then I guess it's no wonder the device gets hot, you're blowing it up! Jeroen
Reply by ●December 14, 20042004-12-14
Stupid me! You were right! I cut the PCB traces of the VCCINT pins off the 3V3 rail and straped them to 1V5 - works perfectly! No heat, no config mess-up. Thanks for the advice. I guess it was obvious to the experinces guys out there. I slaped myself a few times after carefully looking over the datasheet. I guess now I have to clean up my reputation :). Thanks for helping! Alex.
Reply by ●December 14, 20042004-12-14
Stupid me! You were right! I cut the PCB traces of the VCCINT pins off the 3V3 rail and straped them to 1V5 - works perfectly! No heat, no config mess-up. Thanks for the advice. I guess it was obvious to the experinces guys out there. I slaped myself a few times after carefully looking over the datasheet. I guess now I have to clean up my reputation :). Thanks for helping! Alex.
Reply by ●December 14, 20042004-12-14
Alex Somesan wrote: (snip)> I cut the PCB traces of the VCCINT pins off the 3V3 rail and straped > them to 1V5 - works perfectly! No heat, no config mess-up. Thanks for > the advice. I guess it was obvious to the experinces guys out there. I > slaped myself a few times after carefully looking over the datasheet. I > guess now I have to clean up my reputation :).And now we all know how tough Cyclone is with excess VccINT. -- glen