32 Kbit SPI EEPROM for parameter storage in industrial and mixed-voltage designs
The ROHM BR25S320NUX-WTR is a 32 Kbit serial EEPROM with an SPI interface, organized as 4K x 8 bits. It clocks up to 20 MHz on the SPI bus, which gives a raw read throughput of 20 Mbps — enough for fast parameter recall in motor drives, PLCs, or sensor calibration modules. The supply range spans 1.7V to 5.5V, so it can sit on a 1.8V core rail or a 5V legacy bus without a level shifter. Write cycles take 5 ms per word or page, typical for this density class.
At 20 MHz the SPI clock period is 50 ns. That is fast enough to read the full 32 Kbit array in about 1.6 ms (ignoring command overhead). The write cycle is the bottleneck at 5 ms per page, so bulk writes need a small software delay loop or a status-poll after each page command. The interface is standard SPI mode 0 and mode 3, which most MCU SPI peripherals handle natively. No special timing tweaks needed — just match the clock polarity and phase in the chip select routine.
Package and footprint notes for the layout engineer
The BR25S320NUX-WTR comes in an 8-UFDFN with exposed pad, supplier package code VSON008X2030. That is a 2.0 mm x 3.0 mm body with a 0.5 mm pitch — small enough for space-constrained sensor boards or handheld instruments. The exposed pad on the underside should be soldered to a PCB thermal land and stitched with vias to a ground plane; this pulls heat out of the die during repeated write cycles.
Lifecycle and production status
ROHM lists the BR25S320NUX-WTR as Active on its product status.