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Home > Products > Integrated Circuits (ICs) > Memory > Memory

Microchip Technology 23A256-I/ST

Name: 23A256-I/ST
Brand: Microchip Technology
SKU: 23A256-I/ST
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 23A256-I/ST

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 8-TSSOP (0.173", 4.40mm Width)

Datasheet:: 23A256-I/ST.pdf

Description:: IC SRAM 256KBIT SPI 20MHZ 8TSSOP

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Product details

Overview

23A256-I/ST from Microchip Technology Inc. is a 256 Kbit (32,768 × 8-bit) low-voltage SPI serial SRAM with 1.5–1.95 V supply range, 32-byte page size, HOLD pin support, and industrial temperature rating (−40°C to +85°C). It operates up to 20 MHz at 1.8 V and draws only 3 mA read current at 1 MHz - ideal for battery-powered embedded systems requiring nonvolatile-adjacent fast-access memory.

For engineers reviewing the 23A256-I/ST datasheet, 23A256-I/ST pinout, 23A256-I/ST application, or 23A256-I/ST equivalent, key selection criteria include its ultra-low 1.5 V minimum VCC, 4 µA max standby current at +85°C, SPI-compatible interface with dedicated HOLD functionality, and TSSOP-8 packaging for space-constrained PCB layouts.

Technical Context

The 23A256-I/ST implements a true SPI-compatible serial bus interface with separate SI (data in) and SO (data out) lines, synchronous to SCK, and controlled by CS. Its internal 8-bit instruction register accepts READ (0x03), WRITE (0x02), RDSR (0x05), and WRSR (0x01) commands, all MSB-first.

Three configurable operating modes - Byte (default), Page (32-byte auto-increment within page), and Sequential (full-array wraparound) - are selected via STATUS register bits 7:6. The HOLD pin suspends ongoing SPI transfers without resetting the address pointer, enabling interrupt servicing while preserving transaction state.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	256 Kbit (32,768 × 8-bit) - provides sufficient buffer space for firmware overlays, sensor data logging, or protocol stack staging in resource-limited MCUs.
Supply Voltage	1.5–1.95 V - enables direct integration with 1.8 V logic domains and ultra-low-power SoCs without level-shifting.
Max Clock Frequency	20 MHz at VCC = 1.8 V - supports high-throughput data streaming (e.g., audio buffering or real-time telemetry) over SPI.
Page Size	32 bytes - balances burst efficiency and write granularity; limits maximum single-command write to one page, reducing accidental overwrites.
Standby Current	≤4 µA at +85°C - extends battery life in always-on monitoring nodes where memory remains powered but inactive for extended periods.
Data Retention Voltage	1.2 V minimum - guarantees RAM data integrity during brown-out conditions down to near-threshold supply levels.
Operating Temperature	−40°C to +85°C (Industrial) - validated for deployment in industrial control panels, smart meters, and automotive body electronics.

Pinout & Package

23A256-I/ST is housed in an 8-lead TSSOP package (ST suffix), measuring 4.4 mm × 3.0 mm × 1.05 mm, with 0.65 mm lead pitch and Pb-free matte tin finish. Pin 3 is NC (no connect); all other pins match standard SPI+HOLD assignment.

Pin/Terminal	Circuit Role	Design Meaning
CS (Pin 1)	Chip Select Input	Active-low enable: drives device into active mode when low; forces SO to high-impedance when high, enabling multi-drop SPI bus sharing.
SO (Pin 2)	Serial Data Output	Tri-state output delivering read data on falling edge of SCK; enters high-Z during HOLD or CS high.
NC (Pin 3)	No Connect	Internally unconnected; must be left floating or tied to GND per layout best practice - no electrical function.
VSS (Pin 4)	Ground Reference	Primary return path for all I/O and core logic; requires low-impedance connection to system ground plane.
SI (Pin 5)	Serial Data Input	Accepts instructions, addresses, and write data on rising edge of SCK; sampled only when CS is low and HOLD is high.
SCK (Pin 6)	Serial Clock Input	Master-generated clock synchronizing all SPI transactions; rising edge latches SI, falling edge updates SO.
HOLD (Pin 7)	Hold Control Input	Pauses ongoing SPI transfer when pulled low (with SCK low); resumes from exact byte position upon release - critical for deterministic interrupt latency.
VCC (Pin 8)	Supply Voltage	1.5–1.95 V power rail; requires local 100 nF ceramic decoupling placed ≤2 mm from pin to suppress switching noise.

Key Features

Feature	Design Value
Low-Voltage Operation	1.5 V minimum VCC enables compatibility with next-generation ultra-low-power microcontrollers and energy-harvesting systems.
Hardware HOLD Function	Dedicated pin halts SPI communication mid-transfer without address reset - eliminates retransmission overhead during time-critical ISR execution.
Configurable Access Modes	Byte/Page/Sequential modes selectable via STATUS register - allows optimization for random access latency, burst throughput, or continuous streaming use cases.
Pb-Free & RoHS Compliance	Meets global environmental regulations; TSSOP package uses matte tin terminations compatible with standard SnPb and lead-free reflow profiles.
Industrial Temp Range	Rated from −40°C to +85°C - qualified for deployment in factory automation, building controls, and outdoor IoT gateways without derating.

Applications

Wireless Sensor Node Memory Buffer	Industrial PLC Data Logging
Use Scenario: A battery-powered LoRaWAN node samples temperature/humidity every 5 seconds and buffers 128 readings before transmission. IC Role / Device Role / Timing Role: 23A256-I/ST serves as volatile but fast-access circular buffer memory, interfaced directly to an ARM Cortex-M0+ MCU's hardware SPI peripheral. Use Value: Its 4 µA standby current extends 2xAA battery life beyond 2 years; 20 MHz clock supports rapid flush-to-radio after wake-up.	Use Scenario: A DIN-rail mounted PLC stores last 1000 I/O state snapshots during mains failure to enable deterministic recovery on power restore. IC Role / Device Role / Timing Role: 23A256-I/ST acts as fast shadow RAM holding runtime process images, synchronized with backup supercapacitor-supplied VCC. Use Value: 1.2 V data retention voltage ensures zero data loss during brown-out events lasting up to 100 ms.
Medical Wearable Real-Time Processing	Automotive Body Control Module (BCM)
Use Scenario: An ECG patch digitizes analog leads at 1 kHz, applies FIR filtering in real time, and buffers filtered waveform segments for Bluetooth LE upload. IC Role / Device Role / Timing Role: 23A256-I/ST provides low-latency scratchpad memory for filter coefficient storage and intermediate sample staging between ADC and DSP engine. Use Value: 32-byte page writes minimize SPI overhead during coefficient updates; 1.8 V operation matches wearable SoC core voltage.	Use Scenario: A BCM stores seat position presets, mirror calibration offsets, and lighting profiles across ignition cycles - retained via backup battery. IC Role / Device Role / Timing Role: 23A256-I/ST functions as configuration RAM, loaded at startup from EEPROM and updated dynamically during user interaction. Use Value: HOLD pin allows MCU to service CAN frame interrupts without corrupting ongoing SRAM write sequences to store new settings.

Wireless Sensor Node Memory Buffer

Industrial PLC Data Logging

Use Scenario: A battery-powered LoRaWAN node samples temperature/humidity every 5 seconds and buffers 128 readings before transmission.

IC Role / Device Role / Timing Role: 23A256-I/ST serves as volatile but fast-access circular buffer memory, interfaced directly to an ARM Cortex-M0+ MCU's hardware SPI peripheral.

Use Value: Its 4 µA standby current extends 2xAA battery life beyond 2 years; 20 MHz clock supports rapid flush-to-radio after wake-up.

Use Scenario: A DIN-rail mounted PLC stores last 1000 I/O state snapshots during mains failure to enable deterministic recovery on power restore.

IC Role / Device Role / Timing Role: 23A256-I/ST acts as fast shadow RAM holding runtime process images, synchronized with backup supercapacitor-supplied VCC.

Use Value: 1.2 V data retention voltage ensures zero data loss during brown-out events lasting up to 100 ms.

Medical Wearable Real-Time Processing

Automotive Body Control Module (BCM)

Use Scenario: An ECG patch digitizes analog leads at 1 kHz, applies FIR filtering in real time, and buffers filtered waveform segments for Bluetooth LE upload.

IC Role / Device Role / Timing Role: 23A256-I/ST provides low-latency scratchpad memory for filter coefficient storage and intermediate sample staging between ADC and DSP engine.

Use Value: 32-byte page writes minimize SPI overhead during coefficient updates; 1.8 V operation matches wearable SoC core voltage.

Use Scenario: A BCM stores seat position presets, mirror calibration offsets, and lighting profiles across ignition cycles - retained via backup battery.

IC Role / Device Role / Timing Role: 23A256-I/ST functions as configuration RAM, loaded at startup from EEPROM and updated dynamically during user interaction.

Use Value: HOLD pin allows MCU to service CAN frame interrupts without corrupting ongoing SRAM write sequences to store new settings.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
23K256-I/ST	Higher VCC range (2.7–3.6 V); same pinout, timing, and feature set - but incompatible with 1.5–1.95 V systems.	Targeted at 3.3 V industrial designs; cannot replace 23A256-I/ST in 1.8 V domains without level-shifting or redesign.	Select only if system VCC ≥ 2.7 V and lower standby current is not required.
FM25V05-G	F-RAM technology: unlimited endurance, faster writes, no write delay; 2.0–3.6 V supply; SOIC-8 package (SN), not TSSOP-8.	Eliminates write-time uncertainty in high-frequency logging; higher cost and different package footprint require layout change.	Prefer when >10⁹ write cycles or sub-100 ns write latency are mandatory - not a drop-in replacement.

Compared with 23K256-I/ST and FM25V05-G, the 23A256-I/ST uniquely delivers 1.5 V operation and 4 µA standby in TSSOP-8, making it optimal for compact, battery-sensitive designs where F-RAM cost or 3.3 V bias is prohibitive.

Availability

23A256-I/ST is available at Aetrix Electronics and suitable for wireless sensor nodes, industrial PLCs, medical wearables, and automotive body control modules requiring stable component supply across long production lifecycles.

Supply support for 23A256-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 high-reliability silicon and development tools.

The 23A256-I/ST belongs to Microchip's 23X256 family of SPI serial SRAMs, designed specifically to deliver low-voltage, low-power, pin-compatible memory expansion for deeply embedded systems with strict energy and space constraints.

FAQ

What is the minimum supply voltage required for reliable operation of the 23A256-I/ST?

The 23A256-I/ST requires a minimum supply voltage of 1.5 V for guaranteed functional operation across the full industrial temperature range (−40°C to +85°C), as specified in DC Characteristic D001. Below this threshold, data retention and read/write functionality are not assured - though the device maintains data integrity down to 1.2 V (VDR parameter).

Does the 23A256-I/ST support true SPI Mode 0 (CPOL = 0, CPHA = 0)?

Yes, the 23A256-I/ST operates exclusively in SPI Mode 0: data is sampled on the rising edge of SCK (CPHA = 0) and clock idles low (CPOL = 0). This is confirmed by Figure 1-2 (Serial Input Timing) and Section 2.1, which states SI is latched on the rising edge and SO is updated after the falling edge.

How does the HOLD pin behave during an active SPI transaction on the 23A256-I/ST?

When the HOLD pin is asserted low during an active SPI transaction (with CS low and SCK low), the 23A256-I/ST immediately pauses communication: SI, SCK, and SO enter high-impedance, and the internal address pointer freezes. Upon releasing HOLD (driving it high while SCK remains low), the device resumes exactly where it left off - no reinitialization or address reset is needed.

Can the 23A256-I/ST be used in place of the 23K256-I/ST without hardware changes?

No - the 23A256-I/ST and 23K256-I/ST share identical pinout and timing but differ critically in supply voltage: 23A256-I/ST requires 1.5–1.95 V, while 23K256-I/ST requires 2.7–3.6 V. Substituting one for the other without adjusting the power rail will result in functional failure or damage.

What is the maximum supported clock frequency for the 23A256-I/ST at 1.5 V supply?

At VCC = 1.5 V and TA = −40°C to +85°C, the 23A256-I/ST supports a maximum clock frequency of 10 MHz, as documented in Table 1-2 (AC Characteristics, Param No. 1, FCLK row, first column). Performance degrades below 1.8 V, and 20 MHz operation is only guaranteed at 1.8 V.

23A256-I/ST Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 8-TSSOP (0.173", 4.40mm Width)

Packaging:: Tube

Product Status:: Active

Programmable:: Not Verified

Memory Type:: Volatile

Memory Format:: SRAM

Technology:: SRAM

Memory Size:: 256Kbit

Memory Organization:: 32K x 8

Memory Interface:: SPI

Clock Frequency:: 20 MHz

Write Cycle Time - Word, Page:: -

Access Time:: -

Voltage - Supply:: 1.7V ~ 1.95V

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-TSSOP

23A256-I/ST FAQ

1.How can I place an order for 23A256-I/ST through Aetrix?

Please submit a Request for Quotation (RFQ) for 23A256-I/ST on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 23A256-I/ST reliable?

The price and inventory of 23A256-I/ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 23A256-I/ST is usually 5 days.

3.What payment methods are accepted for 23A256-I/ST?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 23A256-I/ST transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 23A256-I/ST?

23A256-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 23A256-I/ST order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 23A256-I/ST?

For technical support, including 23A256-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 23A256-I/ST requirements.

6.How does Aetrix verify that 23A256-I/ST is sourced from the original manufacturer or authorized distributors?

All 23A256-I/ST products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 23A256-I/ST meets industry standards.

7.What is the process for return or replacement of 23A256-I/ST?

All 23A256-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 23A256-I/ST, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 23A256-I/ST part is unused and in its original packaging.

Return procedure for 23A256-I/ST:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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