Microchip Technology 23A640T-I/ST

Overview

23A640T-I/ST from Microchip Technology is a 64 Kbit (8192 × 8) low-power SPI Serial SRAM operating at 1.5–1.95 V, supporting up to 20 MHz clock frequency, 32-byte page writes, and HOLD functionality for interrupt-safe bus arbitration in embedded microcontroller systems.

For engineers reviewing the 23A640T-I/ST datasheet, 23A640T-I/ST pinout, 23A640T-I/ST application, or 23A640T-I/ST equivalent, key selection criteria include its 1.8 V supply range, industrial temperature rating (−40°C to +85°C), TSSOP-8 package, SPI-compatible interface with SI/SO/SCK/CS/HOLD, and standby current ≤4 µA at +85°C.

Technical Context

The 23A640T-I/ST implements a serial peripheral interface with MSB-first data framing, supports three configurable operation modes (Byte, Page, Sequential) via STATUS register bits 7–6, and uses an internal address pointer that auto-increments during sequential reads/writes with wraparound at 0x1FFF.

HOLD functionality suspends active SPI transactions without resetting the sequence-requiring HOLD assertion while SCK is low-and tri-states SO during pause; the feature is enabled only when the HOLD bit in the STATUS register is cleared to '0'.

Key Specifications

Pinout & Package

23A640T-I/ST is housed in an 8-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm lead pitch, JEDEC MO-153 compliant, footprint-compatible with SOIC-8 but with 30% smaller area and improved thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 23K640-I/ST, the 23A640T-I/ST enables lower system power and direct 1.8 V integration, while FM25V05-G offers nonvolatile write capability at the cost of voltage compatibility and higher unit price.

Availability

23A640T-I/ST is available at Aetrix Electronics and suitable for industrial sensor nodes, medical wearables, automotive body control modules, and smart home hubs requiring stable component supply across long-lifecycle production programs.

Supply support for 23A640T-I/ST 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 leading provider of microcontroller, mixed-signal, analog, and Flash-IP solutions, serving industrial, automotive, consumer, and communications markets with scalable, secure, and energy-efficient silicon.

The 23A640T-I/ST belongs to Microchip's 23X640 family of low-voltage SPI Serial SRAMs, designed specifically for power-sensitive embedded systems needing fast, byte-addressable serial memory with deterministic timing and interrupt-safe bus control.

FAQ

What is the maximum clock frequency supported by the 23A640T-I/ST?

The 23A640T-I/ST supports a maximum clock frequency of 20 MHz when operated at VCC = 1.8 V within the industrial temperature range. At VCC = 1.5 V, the maximum clock drops to 10 MHz. These limits are defined in Table 1-2 AC Characteristics and ensure reliable setup/hold timing for SI and SO signals under worst-case voltage and temperature conditions. The 23A640T-I/ST datasheet specifies these values with test conditions including CL = 100 pF and input rise/fall times ≤5 ns.

Does the 23A640T-I/ST retain data during power-down?

No, the 23A640T-I/ST is a volatile SRAM and does not retain data when VCC falls below the data retention voltage of 1.2 V (per D011 in Table 1-1). Below this threshold, RAM contents are lost. For nonvolatile storage, external backup power or a separate EEPROM/FRAM device is required. The 23A640T-I/ST is intended for active-system buffering-not long-term data persistence.

How does the HOLD function work on the 23A640T-I/ST?

The HOLD function on the 23A640T-I/ST pauses an ongoing SPI transaction without resetting the internal address counter or command state. To activate, HOLD must be asserted low while SCK is low; SO enters high-impedance, and SI/SCK transitions are ignored. Resuming requires bringing HOLD high while SCK remains low. The feature is disabled unless the HOLD bit in the STATUS register is written to '0'. This behavior is fully documented in Section 2.5 and Figure 1-1 of the 23A640T-I/ST datasheet.

What package type is used for the 23A640T-I/ST?

The 23A640T-I/ST uses an 8-lead TSSOP (Thin Shrink Small Outline Package), designated by the "ST" suffix in the part number. It has a 4.4 mm body width, 0.65 mm lead pitch, and complies with JEDEC MO-153. This package offers superior thermal performance and 30% smaller footprint than standard SOIC-8, making it ideal for space-constrained PCB layouts in portable and industrial equipment.

Can the 23A640T-I/ST be used with a 3.3 V microcontroller SPI interface?

No-the 23A640T-I/ST operates strictly at 1.5–1.95 V and is not 3.3 V tolerant. Driving its SI, SCK, or CS inputs with 3.3 V logic violates the absolute maximum rating of VCC + 0.3 V (≤2.25 V max), risking permanent damage. Interfacing with a 3.3 V MCU requires bidirectional level translation on all four SPI signals (CS, SCK, SI, SO). Alternatively, use the pin-compatible 23K640-I/ST, which supports 2.7–3.6 V operation.