Can I interface two 16-bit nvSRAM devices in width-expansion mode with a 32-bit microprocessor data bus?
Yes, you can interface two 16 bit nvSRAM devices in width-expansion mode to a 32-bit microcontroller data bus by combining the 16-bit data bus of each chip and using it as a 32-bit data bus.
To access the memory, make the following connections:
- Connect the controller’s address lines to the corresponding addresses of each nvSRAM (in parallel)
- Connect the control signals (CE#, WE#, OE#) to the corresponding control signals of each nvSRAM.
It is also recommended to pull up the WE# line using a 5.6-kΩ ~ 10 kΩ pull-up resistor. Pulling up CE# and OE# lines is not necessary for the nvSRAM design although it is a common design practice to pull up control signals.
Leave the HSB# pin of both the nvSRAMs unconnected if HSB# is not used; tie them together if HSB# is used. Note that when HSB# pins are tied together, AutoStore Disable mode is not recommended in the application. This is because during power down, HSB# is internally pulled LOW, and so the nvSRAM, which goes LOW first can initiate a Hardware Store in the other nvSRAM, which is undesired in an AutoStore Disabled application. In the AutoStore Enabled mode, this issue does not arise because store is required to happen at power-down. Therefore, ganging HSB# is allowed only in applications where AutoStore is enabled.