Microchip Technology 48L640-I/SN

Overview

48L640-I/SN from Microchip Technology Inc. is a 64-Kbit SPI serial EERAM integrating an 8,192 × 8-bit SRAM core with cell-based hidden EEPROM backup. It operates at up to 66 MHz over SPI Mode 0/3, supports symmetrical read/write cycles with no endurance limit, and delivers 3 μA hibernate current at 85°C. It is used in industrial data loggers where power-fail-safe memory retention is required.

For engineers reviewing the 48L640-I/SN datasheet, 48L640-I/SN pinout, 48L640-I/SN application, or 48L640-I/SN equivalent, key selection criteria include VCAP-supported autonomous store/recall timing (≤10 ms store, ≤200 μs recall), 2.7–3.6 V operation, -40°C to +85°C temperature range, and compatibility with standard SPI masters requiring hold functionality and status register monitoring.

Technical Context

The 48L640-I/SN implements a dual-memory architecture: volatile SRAM for high-speed access and invisible, cell-mirrored EEPROM for nonvolatile backup. Its AutoStore/AutoRecall logic monitors VCC against a 2.30–2.65 V trip threshold and uses energy stored on the external VCAP capacitor (10–50 μF) to complete full-array transfer without host intervention.

It supports SPI Modes 0 and 3 with MSb-first framing, includes a writable STATUS register (BP1/BP0 block protection, ASE, PRO bits), and provides dedicated commands for secure write/read with CRC, nonvolatile user space (2 bytes), and last-written address tracking - all executed via 8-bit opcodes with 2-byte addressing.

Key Specifications

Pinout & Package

48L640-I/SN is packaged in an 8-Lead SOIC (Small Outline Integrated Circuit) with standard 150 mil body width and gull-wing leads. Pin 1 is marked with a beveled corner or dot; pin numbering follows counter-clockwise convention when viewing top side.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EERAM applications.

Compared with 48L640-I/SN, the 48L640-I/MNY offers identical functionality in a smaller footprint but demands tighter layout controls, while the FM25V05-G trades deterministic backup timing for virtually unlimited write cycles and zero external capacitance - making it suitable only where F-RAM's lower density and different failure modes are acceptable.

Availability

48L640-I/SN is available at Aetrix Electronics and suitable for industrial data loggers, smart metering endpoints, PLC I/O modules, and medical sensor hubs requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for 48L640-I/SN includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology Inc. is a U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and memory solutions for industrial, automotive, and communications markets.

The 48L640-I/SN belongs to Microchip's EERAM product line, designed specifically to replace battery-backed SRAM and simplify power-fail-safe data retention in resource-constrained embedded systems.

FAQ

What is the role of the VCAP pin on the 48L640-I/SN?

The VCAP pin on the 48L640-I/SN connects to an external 10–50 μF capacitor that stores energy used exclusively for autonomous SRAM-to-EEPROM backup during VCC collapse. When system voltage drops below 2.30–2.65 V, the device isolates VCC and draws power from VCAP to complete the full-array store within 10 ms - ensuring no data loss even with abrupt power removal. The capacitor must be rated ≥6.3 V and placed close to the 48L640-I/SN.

Does the 48L640-I/SN require a write-enable command before every SRAM write?

Yes, the 48L640-I/SN requires execution of the WREN (06h) command to set the Write Enable Latch (WEL) bit before each WRITE or WRSR operation. The WEL bit resets to '0' after any write completes, on power-up, or upon WRDI command. This hardware-level protection prevents accidental writes - a critical safety feature in industrial systems where spurious noise could corrupt memory contents.

How does the HOLD function behave during an active store operation on the 48L640-I/SN?

The HOLD function has no effect on internal store operations on the 48L640-I/SN. If a store is already in progress (e.g., triggered by VCC drop), asserting HOLD will pause only SPI communication - not the store itself. The device continues transferring SRAM to EEPROM using VCAP power regardless of HOLD or CS state. Once store completes, RDY/BSY clears and normal SPI access resumes, provided CS is asserted and HOLD is deasserted during SCK low.

Can the 48L640-I/SN be used with SPI Mode 1 or Mode 2?

No, the 48L640-I/SN supports only SPI Modes 0 and 3. In both modes, data is latched on the rising edge of SCK and output on the falling edge. Mode 0 uses low-idle SCK; Mode 3 uses high-idle SCK. Modes 1 and 2 - which invert sampling/output timing relative to clock phase - are not implemented in the 48L640-I/SN silicon and will result in corrupted communication or no response.

What is the purpose of the nonvolatile user space in the 48L640-I/SN?

The 48L640-I/SN includes a dedicated 2-byte nonvolatile user space accessible via WRNUR/C2h and RDNUR/C3h commands. Unlike the main SRAM array, this space retains values across power cycles independently and is copied to nonvolatile memory during every AutoStore or STORE operation. It is intended for infrequently changed system-critical data such as calibration offsets, device serial numbers, or security keys - eliminating the need for separate EEPROM or flash partitioning.