Microchip Technology 23A640-I/P

Overview

23A640-I/P from Microchip Technology Inc. is a 64 Kbit (8192 × 8-bit) low-voltage SPI Serial SRAM with 1.5–1.95 V operation, 32-byte page write capability, HOLD pin for interrupt-safe bus pausing, and industrial temperature range (−40°C to +85°C). It interfaces directly with microcontroller SPI ports and supports byte, page, and sequential read/write modes - ideal for space-constrained embedded systems requiring fast, nonvolatile-adjacent volatile memory with minimal power budget.

For engineers reviewing the 23A640-I/P datasheet, 23A640-I/P pinout, 23A640-I/P application, or 23A640-I/P equivalent, key selection criteria include its 1.8 V supply compatibility, 20 MHz max clock at 1.8 V, 4 µA max standby current at +85°C, HOLD functionality timing constraints, and 8-lead PDIP package mechanical fit in legacy designs.

Technical Context

The 23A640-I/P implements a synchronous SPI interface with MSB-first serial protocol, using separate SI (data-in) and SO (data-out) lines and edge-triggered control: instructions and addresses latched on SCK rising edge, SO data updated after SCK falling edge. Its internal 16-bit address counter supports automatic incrementing across byte, page (32-byte boundary wrap), and sequential (full 8K-byte rollover) modes.

Operation is controlled via CS (active-low chip select) and HOLD (active-low pause), with HOLD requiring prior enablement via STATUS register bit 0. The device powers up in standby mode (CS high), enters active state only on CS low, and places SO in high-impedance when deselected or held - enabling multi-device SPI bus sharing without external logic.

Key Specifications

Pinout & Package

23A640-I/P is packaged in an 8-lead Plastic Dual In-line Package (PDIP) with 0.300-inch body width, standard through-hole mounting, and RoHS-compliant matte tin (Sn) lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY14V101QS and IS66WV51216EBLL, the 23A640-I/P uniquely delivers SPI-compatible 64 Kbit SRAM in a compact 8-pin PDIP at 1.8 V with integrated HOLD functionality - making it optimal for cost-sensitive, space-constrained, and ultra-low-power industrial SPI bus expansions where true nonvolatility is unnecessary.

Availability

23A640-I/P is available at Aetrix Electronics and suitable for industrial sensor nodes, medical diagnostic handhelds, smart energy meters, and PLC I/O modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant through-hole packaging.

Supply support for 23A640-I/P 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, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design, manufacturing, and sales operations.

The 23A640-I/P belongs to Microchip's 23X640 family of low-voltage SPI Serial SRAMs, designed specifically for embedded systems needing simple, low-power, pin-efficient volatile memory expansion alongside 1.8 V microcontrollers.

FAQ

What is the maximum operating frequency of the 23A640-I/P at its nominal 1.8 V supply?

The 23A640-I/P supports a maximum clock frequency of 20 MHz when operated at VCC = 1.8 V within the industrial temperature range (−40°C to +85°C). This value is specified in Table 1-2 of the DS22126E datasheet under "FCLK" for VCC = 1.8V (I-Temp). At 1.5 V, the max clock drops to 10 MHz. The 23A640-I/P must not exceed these limits to ensure reliable read/write timing compliance.

Does the 23A640-I/P require external pull-up resistors on its SI, SO, or HOLD pins?

No, the 23A640-I/P does not require external pull-up resistors on SI, SO, or HOLD. SI and HOLD are CMOS inputs with defined VIH/VIL thresholds (0.7×VCC min high, 0.2×VCC max low); SO is actively driven and tri-stated - all compatible with standard microcontroller GPIO outputs. Pull-ups are unnecessary unless bus contention or open-drain emulation is intentionally implemented, which is not supported by the 23A640-I/P's native interface.

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

The HOLD function in the 23A640-I/P is disabled unless bit 0 (HOLD Enable) of the STATUS register is cleared to '0'. When set to '1', the HOLD pin is ignored regardless of its logic level. This bit must be written via WRSR instruction before asserting HOLD low. The 23A640-I/P powers up with HOLD enabled (bit = 0), so explicit STATUS register programming is only needed if disabling HOLD is required - a safety feature preventing accidental hold activation.

Can the 23A640-I/P be used interchangeably with the 23K640 in a design?

No, the 23A640-I/P and 23K640 are not interchangeable due to fundamental supply voltage differences: 23A640-I/P operates at 1.5–1.95 V, while 23K640 requires 2.7–3.6 V. Using 23K640 in a 1.8 V system will cause functional failure; substituting 23A640-I/P in a 3.3 V design risks absolute maximum rating violation (VCC ≤ 4.5 V, but DC characteristics are not characterized above 1.95 V). Their pinouts and protocols are identical, but voltage domain mismatch prohibits drop-in replacement.

What package variants are available for the 23A640-I/P besides the PDIP (P) option?

The 23A640-I/P designation specifies the 8-lead PDIP package ('P' suffix). Other package options for the 23A640 family include 8-lead SOIC ('SN') and 8-lead TSSOP ('ST'), but those carry distinct part numbers: 23A640-I/SN and 23A640-I/ST. The '-I/P' suffix explicitly denotes Industrial temperature grade in PDIP; no other package is encoded in the 23A640-I/P料号. Each variant has unique mechanical dimensions and thermal characteristics - PCB footprints are not compatible across packages.