| Author |
Message |
Alex Somesan
Guest
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 Posted:
Tue Dec 14, 2004 3:13 am Post subject:
Cyclone device misteriously overheats |
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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! |
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Jeroen
Guest
|
| Posted:
Tue Dec 14, 2004 3:31 am Post subject:
Re: Cyclone device misteriously overheats |
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"Alex Somesan" <alex.somesan@gmail.com> wrote in message
news:1102976011.748524.106200@f14g2000cwb.googlegroups.com...
| Quote: | 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 |
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Alex Somesan
Guest
|
| Posted:
Tue Dec 14, 2004 3:39 am Post subject:
Re: Cyclone device misteriously overheats |
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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). |
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Jeroen
Guest
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| Posted:
Tue Dec 14, 2004 4:12 am Post subject:
Re: Cyclone device misteriously overheats |
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"Alex Somesan" <alex.somesan@gmail.com> wrote in message
news:1102977576.801325.220500@c13g2000cwb.googlegroups.com...
| Quote: | 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 |
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Al Clark
Guest
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| Posted:
Tue Dec 14, 2004 4:15 am Post subject:
Re: Cyclone device misteriously overheats |
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"Alex Somesan" <alex.somesan@gmail.com> wrote in
news:1102977576.801325.220500@c13g2000cwb.googlegroups.com:
| Quote: | 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 |
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Alex Somesan
Guest
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| Posted:
Tue Dec 14, 2004 4:46 pm Post subject:
Re: Cyclone device misteriously overheats |
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Jeroen wrote:
| Quote: | "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.
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. |
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Jeroen
Guest
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| Posted:
Tue Dec 14, 2004 5:05 pm Post subject:
Re: Cyclone device misteriously overheats |
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"Alex Somesan" <alex.somesan@gmail.com> schreef in bericht
news:1103024769.952592.211250@f14g2000cwb.googlegroups.com...
| Quote: | 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 |
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Alex Somesan
Guest
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| Posted:
Wed Dec 15, 2004 3:19 am Post subject:
Re: Cyclone device misteriously overheats |
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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. |
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Alex Somesan
Guest
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| Posted:
Wed Dec 15, 2004 3:54 am Post subject:
Re: Cyclone device misteriously overheats |
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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. |
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glen herrmannsfeldt
Guest
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| Posted:
Wed Dec 15, 2004 4:01 am Post subject:
Re: Cyclone device misteriously overheats |
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Alex Somesan wrote:
(snip)
| Quote: | 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 |
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Alex Somesan
Guest
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| Posted:
Wed Dec 15, 2004 4:06 am Post subject:
Re: Cyclone device misteriously overheats |
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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. |
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| Back to top |
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Alex Somesan
Guest
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| Posted:
Wed Dec 15, 2004 4:14 am Post subject:
Re: Cyclone device misteriously overheats |
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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. |
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| Back to top |
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Alex Somesan
Guest
|
| Posted:
Wed Dec 15, 2004 4:15 am Post subject:
Re: Cyclone device misteriously overheats |
|
|
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. |
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Alex Somesan
Guest
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| Posted:
Wed Dec 15, 2004 4:23 am Post subject:
Re: Cyclone device misteriously overheats |
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Stupid me!
You were right!
Tied VCCINT to 1V5 and all works well. No heat at all.
I slaped myself a few times after going over the datasheet again, more
carefuly.
Anyway, stupid rookie mistake. I must clean my reputation now :).
Thanks for helping.
Alex. |
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Jeroen
Guest
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| Posted:
Wed Dec 15, 2004 4:40 am Post subject:
Re: Cyclone device misteriously overheats |
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|
"Alex Somesan" <alex.somesan@gmail.com> wrote in message
news:1103050426.348763.286140@z14g2000cwz.googlegroups.com...
| Quote: | 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.
|
Good to hear it's working now. Luckily it's only a cheap easily replacable
Cyclone and not a Stratix housed in a 1508 pin FBGA package that's worth
several thousand $ :)
Jeroen |
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