Microchip Technology 47L64-I/SN

Overview

47L64-I/SN from Microchip Technology Inc. is a 64-Kbit serial EERAM combining an 8,192 × 8-bit SRAM core with integrated cell-based EEPROM backup, operating over I²C at up to 1 MHz, with 2.7V–3.6V supply, industrial temperature range (−40°C to +85°C), and automatic power-loss data retention for embedded nonvolatile memory applications in metering and industrial control.

For engineers reviewing the 47L64-I/SN datasheet, 47L64-I/SN pinout, 47L64-I/SN application, or 47L64-I/SN equivalent, key selection considerations include VCAP capacitor sizing (10–50 µF), A1/A2 hardware address configuration for multi-device bus sharing, WP pin behavior for upper-quadrant write protection, and AutoStore/AutoRecall timing constraints (TSTORE ≤ 10 ms, TRESTORE ≤ 550 µs).

Technical Context

The 47L64-I/SN implements a dual-memory architecture where the user-accessible SRAM array is mirrored cell-for-cell to hidden EEPROM, with autonomous store/recall triggered by VCAP voltage crossing VTRIP (2.3–2.65 V). Its I²C interface supports standard modes (100/400 kHz/1 MHz) with Schmitt-triggered SDA/SCL inputs and zero-cycle-delay read/write access to SRAM.

Power management relies on external VCAP decoupling (22 µF typical) and internal switchover logic that disconnects VCC during brown-out to sustain EEPROM store using stored capacitor energy. The device uses hardware address pins A1/A2 to support up to four devices on one bus, with no internal pull-ups-requiring explicit VSS/VCC termination.

Key Specifications

Pinout & Package

47L64-I/SN is packaged in an 8-lead SOIC (Small Outline Integrated Circuit) with standard 1.27 mm pitch, RoHS-compliant, and rated for industrial temperature operation. Pin 1 is VCAP; pin 4 is VSS; pin 8 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 47L64-I/SN, the 47L16-I/SN offers identical reliability and interface simplicity at reduced density, while the FM24V01A-G trades capacitor-free operation and extreme endurance for higher quiescent power and different failure-mode characteristics-making 47L64-I/SN optimal for cost-sensitive, battery-constrained industrial logging where 64 Kbit suffices.

Availability

47L64-I/SN is available at Aetrix Electronics and suitable for smart metering, industrial PLC data buffering, and medical device event logging requiring stable component supply, long-term lifecycle assurance, and full industrial temperature compliance.

Supply support for 47L64-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 company specializing in microcontrollers, analog devices, and memory solutions for industrial, automotive, and communications markets.

The 47L64-I/SN belongs to Microchip's EERAM product line, designed specifically to replace battery-backed SRAM and simplify nonvolatile data storage in resource-constrained embedded systems without compromising write speed or endurance.

FAQ

What is the required VCAP capacitor value for reliable AutoStore operation in the 47L64-I/SN?

The 47L64-I/SN requires an external capacitor between VCAP and VSS, with a nominal value of 22 µF. The datasheet specifies a valid range of 10 µF to 50 µF (parameter D15). Using a capacitor outside this range may cause AutoStore failure during rapid VCC drops or extended brown-out conditions. Ceramic or tantalum types are acceptable, but ensure low ESR to maintain sufficient discharge energy for the full 10 ms store duration.

How does the WP pin affect memory access in the 47L64-I/SN?

When the WP pin is driven high, the 47L64-I/SN blocks write operations to the upper 1/4 of its SRAM array (addresses 0x6000–0x7FFF). Writes to this region return ACK for address bytes but NACK for data bytes, halting the transaction. The WP pin has no effect on reads, and if left floating, it is internally pulled low-disabling protection. This feature allows secure storage of calibration constants or cryptographic keys in the protected zone.

Can multiple 47L64-I/SN devices share the same I²C bus, and how is addressing managed?

Yes, up to four 47L64-I/SN devices can share one I²C bus using hardware address pins A1 and A2. These pins set two bits of the 7-bit slave address (with fixed op-code 1010b and third chip-select bit '1'), yielding addresses 0x50–0x53. Since neither A1 nor A2 has internal pull-ups/downs, each must be explicitly tied to VSS or VCC. No software address configuration is needed-address resolution is fully hardware-based and deterministic.

What happens if power is restored during an AutoStore operation in the 47L64-I/SN?

If VCC is restored during an AutoStore operation, the 47L64-I/SN completes the ongoing store to EEPROM, then automatically initiates AutoRecall to reload the data into SRAM. During both operations, the device remains unresponsive on the I²C bus (no ACK responses). The total unavailability window equals TSTORE + TRESTORE (≤10 ms + ≤550 µs), after which normal SRAM access resumes with preserved data integrity.

Is the 47L64-I/SN compatible with standard I²C timing specifications, and what are its maximum speed limits?

Yes, the 47L64-I/SN complies with standard I²C timing: it supports Standard Mode (100 kHz), Fast Mode (400 kHz), and Fast Mode Plus (1 MHz). Its AC characteristics specify FCLK ≤ 1000 kHz, THIGH ≥ 400 ns, TLOW ≥ 600 ns, and rise/fall times ≤ 300 ns/100 ns respectively. It also includes Schmitt-trigger inputs on SDA/SCL for robust noise immunity-critical in electrically noisy industrial environments where the 47L64-I/SN is commonly deployed.