Battery Pack temperature sensor (Thermistor)

Yes. The thermistor is specified in the smart battery data specification, which can be found here:

The thermistor is Semitec 103AT.

================================

Greg Neff VP Engineering

Thanks, Greg.

Unfortunately, that B (3435 +- 1%) is not very widely available. 8-(

Best regards, Spehro Pefhany

That's why everyone uses the Semitec parts. You should be able to get them here:

I don't know how the spec was approved using a single-source part. This is a perfect example of how not to specify a component within a spec.

================================

Greg Neff VP Engineering

Thanks, we`ll do so.

That particular Japanese company is one of the most experienced in the thermistor field (the first by a long shot to develop very cheap yet high precision parts AFAIR), but you`d think there would be second sources..

Best regards, Spehro Pefhany

Why in the world would you care about your battery temp to 1%? Isn't the point just to avoid setting them on fire with the charger?

Well, yes and no. Another problem is cold temperature charging, which can damage cells, reducing the capacity. Also a B value tolerance of

The Smart Battery Data Specification requires that the smart battery be able to report temperature with an accuracy of ±3°K. So, you need an accurate thermistor to meet this performance requirement. I don't know the origin of the requirement.

================================

Greg Neff VP Engineering

Well, what do you expect from a passel of bureaucrats? If they knew their elbow from a hole in the ground, they wouldn't have got the job of bureaucrat in the first place. ;-)

Cheers! Rich

Ishizuka`s representative probably wrote that part of the spec. ;-)

Best regards, Spehro Pefhany

During a design review I stated that my heater-control thermistor circuit could sense the temperature on a display within 5 degrees C. When I was asked if that was good enough, I replied "We're not making beer".

See:

What *were* you making?

Best regards, Spehro Pefhany

nothing available from here?

Martin

Whoa, what incredible performance, wonder how much they run in small quantity.

There are lots of very inexpensive 1% thermistors these days, especially in SMT (eg. 0402). I'd be interested in how they manufacture bead thermistors to that tolerance, considering they change more than 4%/Kelvin.

Best regards, Spehro Pefhany

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

coeff ~= (B/T^2) = +3.8% for B = 3435 @ 300K (Semitec) = +4.7% for B = 4250 @ 300K (Murata)

Best regards, Spehro Pefhany

Ruggedized displays.

Ah, I see. I thought you were displaying the measured temperature (my usual requirement) rather than measuring the temperature of the display!

Best regards, Spehro Pefhany

We could have gotten a more accurate measurement of the display temperature if we had placed the thermistor in the center of the display. However, the useers would not like that.

Un bel giorno Spehro Pefhany digitò:

Digikey gives me nine different models (they differ in resistance tolerance and package): P12007CT-ND P12008CT-ND P12009CT-ND P12010CT-ND P12011CT-ND P12012CT-ND P12013CT-ND P12014CT-ND P12011DKR-ND