Microchip Technology 23A640-I/ST

Overview

23A640-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 23A640-I/ST datasheet, 23A640-I/ST pinout, 23A640-I/ST application, or 23A640-I/ST equivalent, key selection criteria include its 1.8 V supply range, industrial temperature rating (−40°C to +85°C), TSSOP-8 package, and SPI-compatible serial interface with dedicated HOLD and chip-select control.

Technical Context

The 23A640-I/ST implements a synchronous SPI interface with MSB-first data framing, supporting three configurable operation modes-Byte, Page, and Sequential-via STATUS register bits 7–6. It uses rising-edge sampling on SI and falling-edge output on SO, with CS-driven active-low selection and HOLD-enabled pause/resume capability without sequence reset.

Its internal architecture includes an 8-bit instruction register, 16-bit address space, and automatic address increment logic for page and sequential modes. The HOLD function requires prior enablement via STATUS register bit 0 and must be asserted while SCK is low to avoid timing violation.

Key Specifications

Pinout & Package

23A640-I/ST is housed in an 8-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm lead pitch, optimized for high-density PCB layouts and automated surface-mount assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 23K640-I/ST and FM25V05-G, the 23A640-I/ST uniquely balances ultra-low-voltage operation, predictable SPI timing, and industrial temperature reliability-making it optimal for battery-powered, 1.8 V MCU-based systems where endurance exceeds EEPROM but cost remains below F-RAM.

Availability

23A640-I/ST is available at Aetrix Electronics and suitable for industrial sensor nodes, medical handheld diagnostics, automotive body control modules, and smart energy meters requiring stable component supply across extended production lifecycles.

Supply support for 23A640-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 U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and memory solutions for embedded control applications.

The 23A640 belongs to Microchip's serial SRAM product line, designed specifically for low-voltage, SPI-based data buffering in space- and power-constrained embedded systems.

FAQ

What is the minimum supply voltage required for reliable operation of the 23A640-I/ST?

The 23A640-I/ST specifies a minimum supply voltage of 1.5 V per DC Characteristics Table D001. Operation below this threshold may result in undefined behavior, including failed read/write cycles or STATUS register corruption. For robust design, maintain VCC ≥1.55 V across all load and temperature conditions to accommodate tolerance and ripple.

Does the 23A640-I/ST support true SPI Mode 0 (CPOL=0, CPHA=0)?

Yes, the 23A640-I/ST operates exclusively in SPI Mode 0: clock polarity (CPOL) is 0 (idle low), and clock phase (CPHA) is 0 (data sampled on first rising edge after CS assertion). This is confirmed by Figure 1-2 (Serial Input Timing) and Section 2.1, which states data is latched on the rising edge of SCK and output updated after the falling edge.

How does the HOLD function interact with the STATUS register in the 23A640-I/ST?

The HOLD function in the 23A640-I/ST is disabled unless STATUS register bit 0 (HOLD enable) is cleared to '0'. When enabled, pulling HOLD low pauses ongoing SPI transfers without resetting internal address counters. The device resumes from the exact point of interruption upon HOLD returning high while SCK is low, preserving full transaction integrity.

Can the 23A640-I/ST be used interchangeably with the 23K640-I/ST on the same PCB layout?

No-the 23A640-I/ST and 23K640-I/ST share identical pinout and package (TSSOP-8), but differ in supply voltage range (1.5–1.95 V vs. 2.7–3.6 V) and electrical characteristics. Substituting one for the other without adjusting the VCC rail will cause functional failure: 23A640-I/ST cannot operate at 3.3 V, and 23K640-I/ST will not power up at 1.8 V.

What is the maximum supported clock frequency for the 23A640-I/ST at 1.8 V and −40°C?

Per Table 1-2 AC Characteristics, the 23A640-I/ST supports up to 20 MHz clock frequency at VCC = 1.8 V across the full industrial temperature range (−40°C to +85°C). At −40°C, timing margins remain compliant with all min/max specifications including TCSS (50 ns CS setup) and TV (50 ns output valid).