Microchip Technology 47L64T-I/SN

Overview

47L64T-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. It serves as a drop-in nonvolatile SRAM replacement in real-time logging, configuration storage, and metering systems.

For engineers reviewing the 47L64T-I/SN datasheet, 47L64T-I/SN pinout, 47L64T-I/SN application, or 47L64T-I/SN equivalent, key selection criteria include VCAP capacitor support (10–50 µF), WP-enabled memory protection for upper 1/4 array, AutoStore/AutoRecall timing (≤10 ms store, ≤550 µs recall), Schmitt-triggered SDA/SCL inputs, and I²C bus compatibility across 100 kHz/400 kHz/1 MHz modes.

Technical Context

The 47L64T-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 uses open-drain SDA and edge-synchronized SCL, supporting standard addressing with A1/A2 hardware pins enabling up to four devices on one bus.

Power management relies on external VCAP decoupling (22 µF typical) charged via internal switchover circuitry; during brown-out, VCC disconnects and VCAP powers the store operation, ensuring zero-cycle-delay writes remain functional until trip threshold breach. The device enforces write protection only when WP is high, blocking writes to addresses 0x1C00–0x1FFF without affecting reads.

Key Specifications

Pinout & Package

8-Lead SOIC package (3.9 mm × 4.9 mm, 1.27 mm pitch) with exposed thermal pad on TDFN variant; pin 1 = VCAP, pin 8 = VCC. Requires external 22 µF capacitor between VCAP and VSS for AutoStore functionality.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 47L64T-I/ST, the 47L64T-I/SN offers identical functionality in SOIC packaging for legacy footprint compatibility; versus FM24V02A-G, it trades capacitor dependency for hardware-configurable addressing and write-protect granularity - essential for multi-node industrial networks.

Availability

47L64T-I/SN is available at Aetrix Electronics and suitable for smart metering, industrial PLC configuration storage, and medical diagnostic device logging requiring stable component supply, long-term lifecycle assurance, and guaranteed traceable sourcing.

Supply support for 47L64T-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, with global design centers and ISO 9001-certified manufacturing.

The 47L64 product line delivers EERAM technology - merging SRAM speed with EEPROM nonvolatility - specifically engineered for mission-critical data retention in utility, industrial, and medical systems where power resilience is mandatory.

FAQ

What is the function of the VCAP pin on the 47L64T-I/SN?

The VCAP pin on the 47L64T-I/SN connects to an external 10–50 µF capacitor that stores energy used exclusively for AutoStore operations during VCC dropout. When system voltage falls below VTRIP (2.3–2.65 V), the device isolates VCC and draws power from VCAP to complete SRAM-to-EEPROM transfer within ≤10 ms. This pin must be tied to VSS through the capacitor; leaving it unconnected disables nonvolatile backup functionality in the 47L64T-I/SN.

Does the 47L64T-I/SN require firmware intervention to retain data during power loss?

No, the 47L64T-I/SN performs fully autonomous AutoStore and AutoRecall operations without firmware involvement. Upon detecting VCAP voltage crossing VTRIP, it suspends I²C communication, switches to capacitor power, and transfers all 8,192 bytes of SRAM content to EEPROM in parallel. On power restoration, it reloads data into SRAM before re-enabling bus access - all transparently. This behavior is intrinsic to the 47L64T-I/SN silicon design and requires no host processor action.

How does the WP pin affect memory access in the 47L64T-I/SN?

When the WP pin on the 47L64T-I/SN is driven high, write operations to the upper 1/4 of the SRAM array (addresses 0x1C00–0x1FFF) are blocked; attempts return ACK for address bytes but NACK for data bytes. Reads remain fully enabled across the entire 8K×8-bit space. If WP is left floating, it is internally pulled low, permitting unrestricted writes. This hardware-level protection eliminates software overhead for safeguarding critical configuration data in the 47L64T-I/SN.

Can multiple 47L64T-I/SN devices share the same I²C bus?

Yes, up to four 47L64T-I/SN devices can operate concurrently on a single I²C bus using hardware address pins A1 and A2. Each device's A1/A2 combination sets two bits of the 7-bit slave address (with fixed op-code 1010b and third chip-select bit = 1), yielding four unique addresses: 0xA0, 0xA2, 0xA4, and 0xA6. External pull-up resistors must be sized for total bus capacitance (≤400 pF), and all devices must share common VSS and VCC references to ensure reliable arbitration in the 47L64T-I/SN multi-drop configuration.

What is the maximum I²C clock frequency supported by the 47L64T-I/SN?

The 47L64T-I/SN supports I²C clock frequencies up to 1 MHz under industrial conditions (−40°C to +85°C, VCC = 2.7–3.6 V), with guaranteed timing margins for THIGH ≥400 ns and TLOW ≥600 ns. At this rate, byte writes complete in ≤550 ns after clock edge, and sequential transfers sustain full throughput without inter-byte delays. For robustness in noisy environments, 400 kHz or 100 kHz modes may be selected - all three speeds are natively supported without configuration registers or mode switching in the 47L64T-I/SN.