25AA256/WF16K

Memory IC Overview

The Microchip Technology 25AA256/WF16K is a 256 Kbit (32,768 x 8-bit) Serial Electrically Erasable PROM accessed via an SPI-compatible serial bus. It operates within a supply voltage range of 1.8V to 5.5V and supports clock frequencies up to 10 MHz. The device features a 64-byte page size, self-timed erase/write cycles with a maximum duration of 5 ms, and block write protection capabilities. It includes built-in power-on/off data protection and a write enable latch. Endurance is rated for 1,000,000 erase/write cycles with data retention exceeding 200 years.

Memory IC Feature Summary

• Supports low-power CMOS technology with standby current as low as 1 µA at 5.5V.
• Includes hardware write-protect pin and software-configurable block protection for none, 1/4, 1/2, or all of the array.
• Features a HOLD input to pause serial communication without resetting the sequence, allowing host servicing of higher priority interrupts.

Memory IC Applications

• Data logging in industrial control systems
• Configuration storage for microcontrollers
• Parameter storage in consumer electronics

Memory IC Procurement Notes

Verify the specific suffix 'WF16K' against official Microchip documentation to confirm it denotes Wafer on Frame packaging. Standard datasheets typically list PDIP, SOIC, TSSOP, and DFN packages; ensure the ordering information matches the required form factor. Confirm temperature grade (Industrial I or Extended E) and RoHS compliance status directly with the manufacturer before procurement.

Memory IC Selection Notes

Select this component when SPI interface compatibility is required alongside low-voltage operation down to 1.8V. Ensure the application does not require page writes crossing physical boundaries, as data wraps around within the same page. Verify that the system design accommodates the 5 ms maximum internal write cycle time and utilizes the WREN instruction prior to write operations.

Memory IC Part Context

This part belongs to the 25XX256 family of 256 Kbit Serial EEPROMs from Microchip Technology. It shares functional similarities with the 25LC256 but differs in operating voltage specifications, supporting a lower minimum voltage of 1.8V compared to the 2.5V minimum of the LC variant. Both devices utilize the same SPI protocol and pinout configurations.

Memory IC Replacement Considerations

The 25LC256 serves as a direct functional substitute if the system voltage remains above 2.5V. Other 256 Kbit SPI EEPROMs from different manufacturers may be compatible provided they support the same SPI mode and voltage requirements.

Memory IC FAQ

How does the HOLD pin function during serial communication?

The HOLD pin suspends transmission to the device while in the middle of a serial sequence without requiring retransmission. It must be held high when not in use and pulled low while SCK is low to invoke the hold function.

What happens if a page write crosses a physical page boundary?

If a page write command attempts to write across a physical page boundary, the data wraps around to the beginning of the current page, overwriting previously stored data, rather than writing to the next page.