Options for semi-permanent memory in a low-energy setting


(Hopefully this will be broad enough to be on-topic.)

I'm looking for options to store several megabytes of data over the period of a few weeks in a coin-cell powered application. The data doesn't need to survive a power outage (dead battery, etc.), but I do expect to perform several hundred reads and writes over the life of a single battery.

What technology type would be the most power efficient? The flash options I'm looking at (such as the m24px80) have fairly substantial current draw on write (15mA @ 3V). What other options are there?

Best Answer

It sounds like you are looking for a low-power Static RAM (SRAM). You need to look at devices that are specified for low-power or "ultra low-power". For long battery life, low standby power can be especially important.

Here is an example from Cypress: CY62167DV30 which lists a typical standby current of 2.5µA

A supervisory circuit for controlling SRAM power and chip-enable is often also used. One example is the TPS3613-01 from TI

Regarding the Micron M25PX80 NOR Serial Flash device you referenced: For only a few hundred reads and writes over the life of the battery, the 15mA write current may not be such a big concern if you can take advantage of the "Deep power-down" mode when the device is idle. Specifications for that mode indicate a maximum current of 10µA (Device Grade 6).