48L256-I/SN

Overview

The Microchip Technology 48L256-I/SN is a 256-Kbit Serial EERAM featuring an SRAM core with hidden EEPROM backup. It operates within a voltage range of 2.7V to 3.6V and supports SPI clock frequencies up to 66 MHz. The memory array is organized as 32,768 x 8 bits. Key electrical characteristics include a maximum active current of 5 mA, standby current of 300 μA, and hibernate current of 3 μA at 85°C. The device ensures data retention for 100 years at 55°C and supports a minimum of 100,000 store cycles.

Feature Summary

• Provides unlimited read and write operations through standard serial SRAM protocol with symmetrical timing.
• Features hidden EEPROM backup that automatically mirrors SRAM data cell-for-cell during power disruptions.
• Includes a 16-bit nonvolatile user space separate from the main SRAM array for configuration storage.
• Supports hardware-based block write protection and secure write/read operations with CRC verification.

Applications

• Industrial control systems requiring persistent data storage without complex software management
• Embedded applications needing fast random access memory with automatic nonvolatile backup
• Data logging devices where power loss events must not result in data corruption

Procurement Notes

Verify the specific suffix 'I' confirms industrial temperature range (-40°C to +85°C) and 'SN' indicates the 8-lead SOIC package. Confirm the datasheet revision matches the design requirements. Ensure system design includes the required VCAP capacitor between pin 3 and ground for proper auto-store functionality during brown-out events.

Selection Notes

Select this component when high-speed SPI interface is required alongside nonvolatile data retention. It is suitable for designs needing immediate data availability without initialization delays associated with traditional EEPROMs. Consider the 3.3V operating voltage and low standby current for battery-powered or energy-efficient systems. Verify compatibility with SPI Mode 0 and Mode 3 protocols used by the host microcontroller.

Part Context

The 48L256 belongs to the Microchip 48L series of Serial EERAM devices. This family combines the speed and endurance of SRAM with the nonvolatility of EEPROM. The -I/SN variant specifically denotes the industrial temperature grade and surface-mount SOIC packaging, distinguishing it from other voltage ranges or package options available in the broader product line.

Replacement Considerations

Check for direct cross-references such as the 48L640 for larger capacity needs. Ensure substitute parts support the same 2.7V-3.6V supply range and 66 MHz SPI speed. Verify pinout compatibility for the 8-lead SOIC package if replacing on existing PCBs.

FAQ

How does the device handle data preservation during a power failure?

The device monitors VCC levels. If voltage drops below a threshold, it uses energy stored in the external VCAP capacitor to automatically transfer all SRAM data to the hidden EEPROM array before power is fully lost.

What is the function of the HOLD pin?

The HOLD pin allows the user to pause serial communication mid-sequence without resetting the address counter or command state. It suspends data transfer while keeping the device selected.

Can the hidden EEPROM be accessed directly by the user?

No, the EEPROM backup is invisible to the user. Data transfers between SRAM and EEPROM are handled automatically by internal circuitry or via specific Store/Recall commands that manage both arrays simultaneously.