Low power accelerometer suggestions?  - Page 1
Forum section: electronics / projects

author: robint91
author_rank: Contributor
timestamp: April 08, 2018, 05:53:46 pm
content: I have a few design using the NXP/Freescale MMA8652. Great little part, low power and some nice wake-up/interrupt modes. These make it ideal for low power applications. And it is cheap, and comes in a decent package.But the horror of lead times strikes again,Farnel, jan-2019,http://be.farnell.com/nxp/mma8652fcr1/accelerometer-3-axis-digital-dfn/dp/2377758?CMP=GRHB-OCTOPARTDigikey, aug-2018Mouser, aug-2018Anyone an Idea why this is happening? Because this isn't normal anymore. Those lead times keep being extended Last time I could buy them was somewhere in june last year.I don't find any suitable replacement yet? ST has a few but they consume more power and are more expensive.I use it to detect simple motion just to wake up the microcontroller and do some sensing. Nothing fancy.Sigh let's respin all these boards....sigh...

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 08, 2018, 06:14:30 pm
content: ADXL362:http://www.analog.com/en/products/sensors-mems/accelerometers/adxl362.htmlGranted it's much more expensive.Would the LIS3DHTR from ST not fit the bill? It's available on Digikey (big stock) and low cost.

author: Jeroen3
author_rank: Super Contributor
timestamp: April 08, 2018, 07:23:12 pm
content: Yeah, it's bad.Long lead times.Did you ask NXP directly?

author: tdarlic
author_rank: Contributor
timestamp: April 09, 2018, 09:47:31 am
content: I'm in the same place as you. I still have the 200 on hand and about 300 boards yet to assemble. I have 300 backordered in Jan if I'm not wrong from Farnell UK and at that time said it will be delivered beginning of May so still waiting.I have just redesigned the board to accept MMA8452QT and will order the test PCBs this week.Low power is not so essential to me but I believe this one is even lower power than 8652/3I think price is the same or similar.http://export.farnell.com/nxp/mma8452qt/accelerometer-12-8bit-3axis-16qfn/dp/1842360Please do not buy them all now.

author: tdarlic
author_rank: Contributor
timestamp: April 09, 2018, 09:58:28 am
content: Forgot to mention. If u are really desperate: only place I found the MMA8652 waswww.iodparts.comThey quoted me 100PCS for $5.85 each on Jan-31st

author: Gribo
author_rank: Frequent Contributor
timestamp: April 09, 2018, 01:04:19 pm
content: What sort of performance do you require from the device? ST and Bosch might have some devices in a similar form factor.Also, the 8452 has two other family members, which can be dropped in as replacements.

author: german77
author_rank: Regular Contributor
timestamp: April 09, 2018, 03:06:36 pm
content: LIS3DETR on Mouser is cheap $1.72, available, has wake functions and it's low power. The only downside is it's 8-bit resolution.I have never used it but look's like an excellent candidate.

author: IDEngineer
author_rank: Super Contributor
timestamp: April 10, 2018, 02:53:23 am
content: We are very sensitive to having second sources. I did an exhaustive analysis of the accelerometer chip market when specifying a part for a design about a year ago. Saving you all the agony of the long story: I narrowed it down to the STMicro LIS2DH (2mm package) and the STMicro LIS3DH (3mm package). The former is stocked deeper, which suggests higher volumes and thus perhaps better longevity, but the latter is pin compatible with at least ST's own LIS331, Analog's ADXL344 and ADXL346, and several parts from Kionix. In other words, the LIS3DH appears to conform to a psuedo-standard for three axis accelerometers in the industry.Keep in mind that pin compatibility may not equal firmware compatibility, but they all have a WHO_AM_I command that your firmware can use to query which part is installed today and alter its behavior accordingly.I went with the LIS3DH and haven't had any availability issues. About a buck in 100's. FWIW, DigiKey presently has 132K pieces in stock so it doesn't appear to be going anywhere soon. ST's spec sheets and appnotes can be a bit cryptic at times, but the part does work well.Hope this helps!

author: diyaudio
author_rank: Frequent Contributor
timestamp: April 10, 2018, 12:52:31 pm
content: Quote from: IDEngineer on April 10, 2018, 02:53:23 amThank you so much for this. Was on the same research path, The STMicro LIS2DH (2mm package) and the STMicro LIS3DH (3mm package) are good candidates from a cost sensitive point of view.

author: IDEngineer
author_rank: Super Contributor
timestamp: April 10, 2018, 03:02:25 pm
content: Quote from: diyaudio on April 10, 2018, 12:52:31 pmYou're very welcome. The LIS3DH is a good part. We had an aliasing issue a while back (a source of vibration at a higher frequency than expected), and were able to address it by increasing the update rate and adjusting our in-firmware filtering, thus avoiding a hardware rev. Fastest update rate at full resolution is ~1500Hz IIRC, so there are faster parts out there, but most applications don't need more than 1500Hz. Can't beat it for the price... thank you, cellphones!