New pressure transducer

I know I'm starting to sound repetative, but from the perspective of someone who does homebrew electronics, this type of surface mount technology is just evil.

If you're looking for high accuracy, get a high-resolution A/D converter and oversample it (look up Atmel application note AVR-121 for how to do it).

The data rate is pretty low - 2hz at 17 bits. The MPX41xx series has a bandwidth of at least 500hz and a slew rate to match it.

Mouser doesn't have a listing of the product, and digi-key only has the -D01 part available in quantities of 500.

Glen Overby

"This unit comes in a newly developed plastic housing. Normal hot-air rework will destroy this sensor. "

Not very useful, eh?

Doug

Um, gents....

"Breakout board is coming soon."

THAT'S the ticket...

I missed _that_ gem. I hope this isn't a trend; I've figured I'll end up owning one of those devices and paying the UGH! price for solder paste.

Nope!

I wonder how long the supply of Motorola (now Freescale) MPX[A]41xx parts will hold out. The alternatives I found at DigiKey weren't very appealing. The new accelerometers from Analog Devices are SMT devices that have pads only on the bottom (no legs) and are no fun to solder with an iron.

For experimenters, again - there's a breakout board coming from sparkfun.

I have played with the MPX4115 units, what disappointed me is their lack of temperature compensation. Maybe these new units will get it right...

One problem is that there are not many home electronics experimenters left any more so it's not profitable for companies to make parts that we can solder. (sigh) Larry Lobdell Jr.

Hi, Larry,

I don't know that the home electronics hobbiest has ever been a consideration for components makers, but usability of the packages is indeed still a concern. We don't necessarily think about prototyping issues in particular, but we do worry about whether customers will be able to handle certain package types. Whether they're building protos or doing production, they need to have the equipment, process flows, handlers, etc, to use parts, so when we bring new chips to market, packaging gets a lot of consideration.

You'd hate to have all the features, performance and price only to lose an opportunity due to manufacturing challenges.

As an electronics professional AND tinkerer, I worry about this stuff. But when I go to the local hobby supply store (Tanner's in Carrollton, Texas), I still see plenty of hobbiests in there, and there are still plenty of user-friendly-packaged parts, too. I'm pleasantly surprised by that and able to not worry as much. I think it's key that we're always able to tinker.

Right now, my business unit is doing a new 4-lead analog temp sensor. It comes in a 1mm x 1.3mm package. It's scarily small. But if you can get the pads down on the board right, then it's possible to hand mount it. It's a PITA, but it's possible.

Doug

This sensor has appeal for several reasons...

at 14 (I think) bit resolution the reading rate is 9hz, plenty fast enough for altimiter and DD applications.

Its digital output, all compensation filtering etc is done internally, do not need an analog section on the alt with it requisite filtering needs etc.

It's I2C output meaning it and an eeprom or other I2C devices can share the same microcontroller ports.

3.3volts at very low power consumption. For altimeter only applications can power it and a pic with a button lithium cell for a considerable amount of time.

It gives temperature output as well as pressure allowing a more accurate calculation of altitude (can't be done with the MPX4115 devices by itself, only pressure output on those).

Soldering isn't that bad, tin the pads and small tip iron on the pad will sock that chip down quite nicely.

As far as the MPX4115, you should now be using the MPX6115 device. Same functions, better environmental insensitivity.

For acceleromters, the Freescale MMA2201 is available in a soldering friendly SOIC package. I just finished a prototype acceleromter with this device and quite impressed with its performance. Very low noise signal.

--jd

Glen Overby wrote:

Have you looked at the Freescale "Compensated Pressure Sensors"? Their product selection guide lists these parts:

MPX2010, MPX2053, MPX2102 MPX2202, MPX2050, MPX2100, MPX2200

I happened to be reading the selection guide this evening while deciding what pressure sensor I would use next... since my last one disentegrated on a dirt road today (it was only a payload). It looks like the MPXAZ4100A6U.

Glen Oh, but the rocket made a nice "whoosh" sound just before the "pop" sound of the impact