Cyclone III FPGA Temperature Measurement.....

The pin connection guidelines for the Cyclone III:

http://www.altera.com/literature/dp/cyclone3/pcg-01003.pdf

Do not list THERM_P/THERM_N pins. This means there is no thermal diode.

You could check the pinout for your specific part (which you did not state):

http://www.altera.com/literature/lit-dp.jsp?category=cyc%203&showspreadsheet=y

However, you're probably not going to be able to measure the die temperature. The best you can do is measure the case temperature using an external device.

Cheers,

Dave

Hi Frank,

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You can measure temperature by forward biasing a substrate or PCI clamp diode.

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Have you ever implemented such a circuit? Any details?

An FPGA thermal diode is usually a diode-connected transistor, which can be sensed by say an ADM1032 I2C device

http://www.onsemi.com/pub/collateral/adm1032-d.pdf

I thought I'd read a warning not to use regular diodes for this application ...

How would you use a clamp diode in this manner? You'd have to raise the current-source voltage above VCCIO so that the diode conducted right?

Cheers,

Dave

Hi Dave,

Thanks for your reply.

I think, the in built temperature sensor is not available in the CycloneIII devices.

But I have seen, some one posted in the altera forum, he did the i2c communication with the

temperature sensor from the DE0 in CyloneIII fpga.

Do you have any idea about it?

We are planning to measure the board temperature instead of measuring the die.

Thanks for your replies.

Regards,

Venkatesh

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We are planning to measure the board temperature instead of measuring the die.

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Then that is fairly simple.

Are you designing a board, or do you already have a board? If the board has a board-level temperature sensor, then all you need is the read the sensor, eg., using I2C or SPI (two common interfaces for sensors).

Provide a little more detail, and I'll point you in the right direction.

Cheers,

Dave

The suggeston to use substrate or clamp diode for temperature measurement isn't but a reminder to a general method used in semiconductor testing. The details have to be worked out. You are right, that we can't expect a similar ideal behavior as with a dedicated sensor diode built into Stratix devices. The diode characteristic must be possibly calibrated and we should be aware of supply rail voltage drops. Needless to say that the test current should be choosen with respect to maximum ratings.

I imagine, that the methode can be useful at least during development, not necessarily for regular operation due to possibly limited reproducibility.

Regards,

Frank

Thanks Dave.

We have already designed Board is available. In the Board schematics we don't have a on-board sensor(LM Series etc).

But some one told me that, we can measure temperature using the on-board transistor(transistor acts as a diode

(Like MMBT3904)).

We are checking for such type of transistor is available in our board or not?

Do you have any idea about this type measurement and devices used for the temperature measurement?

Regards,

Venkatesh

--- Quote Start ---

The suggeston to use substrate or clamp diode for temperature measurement isn't but a reminder to a general method used in semiconductor testing. The details have to be worked out. You are right, that we can't expect a similar ideal behavior as with a dedicated sensor diode built into Stratix devices. The diode characteristic must be possibly calibrated and we should be aware of supply rail voltage drops. Needless to say that the test current should be choosen with respect to maximum ratings.

I imagine, that the methode can be useful at least during development, not necessarily for regular operation due to possibly limited reproducibility.

--- Quote End ---

Ok, thanks!

Cheers,

Dave

--- Quote Start ---

We have already designed Board is available. In the Board schematics we don't have a on-board sensor(LM Series etc).

But some one told me that, we can measure temperature using the on-board transistor(transistor acts as a diode

(Like MMBT3904)).

We are checking for such type of transistor is available in our board or not?

Do you have any idea about this type measurement and devices used for the temperature measurement?

--- Quote End ---

You are the one with the schematic, so it should be easy for you to see.

If the board designer intended you to be able read temperature, and there is a remote diode-connected-transistor placed near the Cyclone III, then there needs to be an ADM1032 or similar sensor connected to that transistor. Read the data sheet for the ADM1032 - it outputs two different currents, averages the voltage measurements for each current, and then calculates an estimate of the temperature. If you do not have that logic built into your board, you will not be able to measure the temperature using any logic on your board.

You could measure the temperature using an external device, eg., an IR gun or an iButton temperature sensor.

Cheers,

Dave

Thanks for your reply Dave.

In our board schematics, we don't have a on-board temperature sensing device.

We have only one component ADM1185, which is a supply monitor and sequencer.

then we dont have any option to measure even on-board temperature also.

So we are planning to go for some external to measure it.

Thanks for your guidance.

Regards,

Venkatesh