Microchip Technology AT24CS32-SSHM-T

Overview

AT24CS32-SSHM-T from Microchip Technology is a 32-Kbit I²C-compatible serial EEPROM with factory-programmed 128-bit unique serial number, organized as 4,096 × 8 bits, operating from 1.7V to 5.5V, and rated for -40°C to +85°C industrial temperature range. It supports Standard (100 kHz), Fast (400 kHz), and Fast Mode Plus (1 MHz) I²C speeds and includes hardware write protection via WP pin for full-array data security in embedded control and asset tracking systems.

For engineers reviewing the AT24CS32-SSHM-T datasheet, AT24CS32-SSHM-T pinout, AT24CS32-SSHM-T application, or AT24CS32-SSHM-T equivalent, key selection considerations include its guaranteed-unique 128-bit serial number (non-volatile, non-overlapping across CS Series), 5 ms max self-timed write cycle, 1,000,000 write endurance, 100-year data retention, and compatibility with space-constrained designs using SOIC, TSSOP, UDFN, or SOT23 packages.

Technical Context

The AT24CS32-SSHM-T implements a two-wire I²C slave interface with Schmitt-triggered, noise-filtered SDA and SCL inputs, supporting bidirectional data transfer with ACK/NACK protocol and Start/Stop condition detection. Its internal architecture includes a high-voltage generation circuit for EEPROM programming, hardware address comparator for multi-device bus addressing (A0–A2), and power-on reset (POR) with 100 µs tPUP delay before command acceptance.

Memory is organized into 128 pages of 32 bytes each, enabling partial page writes and sequential/random reads. The 128-bit serial number resides in a dedicated, read-only memory block accessed via device address '1011b', physically isolated from user EEPROM space and permanently locked during wafer fabrication - no user programming or overwrite capability exists.

Key Specifications

Pinout & Package

AT24CS32-SSHM-T is supplied in an 8-lead SOIC package (3.9 mm × 4.9 mm, 1.27 mm pitch), with pins arranged as follows:

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT24CS32-SSHM-T, AT24C32D-SSHM-T removes the 128-bit serial number while preserving all EEPROM functionality and pinout - ideal for cost-optimized designs without traceability needs. M24C32-WMN6TP trades the unique serial number for broader temperature and ESD specs, making it viable for harsher environments where identity is handled elsewhere.

Availability

AT24CS32-SSHM-T is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and smart energy metering requiring stable component supply, long-lifecycle assurance, and guaranteed device uniqueness.

Supply support for AT24CS32-SSHM-T 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 is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and memory solutions, with emphasis on reliability, longevity, and industrial-grade qualification.

The AT24CS32-SSHM-T belongs to Microchip's CS-Series Serial EEPROM product line, designed specifically to eliminate manufacturing-line serialization by embedding a permanent, globally unique 128-bit identifier - targeting asset tracking, regulatory compliance, and secure device onboarding applications.

FAQ

What is the purpose of the factory-programmed 128-bit serial number in the AT24CS32-SSHM-T?

The 128-bit serial number in the AT24CS32-SSHM-T is permanently programmed during wafer fabrication and cannot be altered or erased. It is globally unique across all CS-Series EEPROMs, enabling unambiguous device identification for asset tracking, regulatory compliance, and secure firmware binding without requiring external serialization infrastructure. This value resides in a dedicated read-only memory block separate from the 32-Kbit user EEPROM space.

Does the AT24CS32-SSHM-T support I²C Fast Mode Plus (1 MHz), and what are the voltage requirements?

Yes, the AT24CS32-SSHM-T supports I²C Fast Mode Plus at up to 1 MHz, but only when VCC is between 2.5V and 5.5V. At lower voltages (1.7V–2.5V), it operates in Standard (100 kHz) or Fast (400 kHz) mode. This voltage-dependent speed scaling ensures signal integrity and timing margin compliance across its full operating range.

How does the Write-Protect (WP) pin function on the AT24CS32-SSHM-T?

The WP pin on the AT24CS32-SSHM-T provides hardware-level write inhibition: when driven to VCC, it disables all write operations to the entire 32-Kbit memory array, including page writes and serial number reads (which are read-only anyway). When grounded, normal write functionality is enabled. If left floating, the pin is internally pulled down, allowing writes - though Microchip recommends hardwiring WP for deterministic behavior.

What is the maximum write cycle time for the AT24CS32-SSHM-T, and how does it affect firmware design?

The AT24CS32-SSHM-T guarantees a maximum self-timed write cycle duration of 5 ms. This fixed upper bound allows firmware to implement precise timeout handling - for example, using a 10 ms poll-and-wait loop or non-blocking state machine - without risk of indefinite blocking. No external timing components or complex acknowledge polling logic are required beyond standard I²C protocol.

Can the AT24CS32-SSHM-T operate reliably at 1.7V, and what performance trade-offs apply?

Yes, the AT24CS32-SSHM-T is fully specified for operation down to 1.7V, supporting Standard and Fast I²C modes at that voltage. However, Fast Mode Plus (1 MHz) is disabled below 2.5V, and standby current increases slightly (to ≤1.0 µA at 1.7V). All timing parameters, including tAA and tWR, remain within datasheet limits, ensuring robust low-voltage functionality in battery-powered or energy-harvesting systems.