Any very low power SPI flash?

Hi, i am developing a battery (CR2032) powered device that must log a few sensors for a minimum of 3 months every minute but longer would be better. The duty cycle is very low. In order to save the data i will be using an SPI flash (16Mb). I was comparing at Atmel and SST (Microchip) and SST seems to have the lowest current consumption device (max 15uA at standby) but it is still a bit high compared to the microcontroller (MSP430 for instance) and other sensors. Acceptable but high. Does any one knows any other SPI flash with lower idle current and reasonble availability?

Second.. does any one knows if there is any problem on powering the flash directly from the battery? Just asking becouse if there is a problem i will have to use a boost converter (more costly and less power efficient).

Thank you!

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Reply to
Sink0
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How about turning off the power to the flash when you're not using it ?

Reply to
Arlet Ottens

MSP430 with embedded Ferromagnetic RAM (FRAM)

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or MSP430 with external FRAM (info:

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in conjuction with GP MOSFET (2N7002) to control power line to the FRAM.

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StoneThrower
www.dgmicrosys.com
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Reply to
Stonethrower

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I liked the power down idea, Very simple adn reduce to 1uA current due to the Mosfet. FRAM devices got very low memory or bulky packages so not the best solution for now. Any comment on powering a 2.7V flash from 3.0V coin battery? Thank you!

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Reply to
Sink0

I think you would do better to find a SPI Flash Chip that is specified in the data sheet to operate over a range of voltages that includes the range of voltages you are likely to see from your battery. Do note that some coin cells, when new, will show a higher voltage than the nominal

3.0 volts. I have seen some as high as almost 3.3V.

The Micron M25P15 part is specified to work correctly with a supply voltage range of 2.7 -> 3.6 volts. This should work well with a coin cell lithium battery as long as you make sure that your circuit shuts down operation when the battery voltage nears 2.7V at dischard of the batteryy.

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Michael Karas
Carousel Design Solutions
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Reply to
Michael Karas

Yep - power from a spare uC pin. It'a worked for me.

Reply to
rob

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And buffer it to internal FLASH and/or EEPROM first.

Reply to
Anda

The idea of using the internal memory falls apart when you consider

24 x 60 x 90 = 129600. With 3 sensors * 16 bit you need 7-800 kB. An internal controller is going to be expensive...

I don't think that there are SPI flashes available with wide voltage ranges. If I were you, I would regulate the system to 1.8V, using an

1.8V SPI Flash.

If you power the SPI flash from an I/O Port, then you may run into a problem with power on reset times, forcing the SPI flash to be turned on for an extended time eating power.

You can overcome this by caching some data before you turn on the SPI flash. With 3 sensors @ 16 bit, and caching for an hour, you need 360 bytes of RAM which is probably OK. Writing to internal EEPROM/FRAM, might also be OK-

Not sure if you can get FRAM parts with 1.8V. There are 0.9V parts in the AVR series which can run from std AA batteries, and contain a boost to 3.3V.

Best Regards Ulf Samuelsson

Reply to
Ulf Samuelsson

Winbond W25Q16BV? Supply voltage operating range 2.7 to 3.6 volts, typical power-down current 1 µA (achievable by using the SPI "power down" command).

Chris

Reply to
Christopher Head

Haven't tried this with flash, but a serial EEPROM had a separate battery power pin the would lock the device if Vcc wasn't a diode drop higher. As a previous poster noted, the 3.0 on the data sheet is a MINIMUM voltage, and they don't give a max, which made my devices useless until I switched power pin from 3.3 to 5 V.

Reply to
Gary Lynch

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