AT21CS01-STUM-T - 1Kbit Single-Wire Serial EEPROM | Microchip
MPN: AT21CS01-STUM-T ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.55 | $5.50 |
| 100 | $0.43 | $43.00 |
| 500 | $0.36 | $180.00 |
| 1,000 | $0.3 | $300.00 |
| 3,000 | $0.26 | $780.00 |
AT21CS01-STUM-T Overview
A serial EEPROM is a non-volatile memory device accessed sequentially over a low-pin-count bus. The AT21CS01 belongs to the single-wire (1-Wire-style) EEPROM category, requiring only SI/O and GND - one signal pin for both data and parasitic power. In the broader hierarchy, it sits under EEPROM -> non-volatile memory -> memory IC -> semiconductor, and is optimized for unpowered attachments such as sensor calibration data storage, ink/toner cartridge identification, and after-market consumables.
Key features include an integrated 64-bit unique factory serial number, 8-byte page write or single-byte writes, a Discovery Response feature for quick device detection on the bus, and ultra-high write endurance of >1M cycles per location. The 1.7V to 3.6V supply range makes it directly compatible with 1.8V and 3.3V rails common in modern MCUs. The SOT-23-3 footprint occupies just 2.9 x 1.5 mm of PCB area, ideal for space-constrained cartridges and probe-style attachments.
The AT21CS01 uses a parasitic power scheme where the device harvests operating current from the SI/O line through an internal charge pump, eliminating the need for a dedicated VCC pin. Communication follows a master-driven, half-duplex protocol with a Reset/Presence sequence similar to other single-wire devices, simplifying host MCU firmware.
Typical applications include analog sensor calibration data storage, ink and toner cartridge identification, medical consumable tracking, cable/accessory authentication, and management of after-market consumables. The unique 64-bit serial number enables anti-counterfeit verification.
Designers must provide a pull-up resistor on the SI/O line (typically 2.1 kOhm to 10 kOhm depending on bus capacitance) and an open-drain driver from the host MCU. Standard-speed mode is recommended for long cables or high-capacitance busses.
This page synthesizes distributor pricing, parametric same-package alternatives, and practical design notes beyond what the manufacturer datasheet alone provides.
Drop-in alternatives for AT21CS01-STUM-T — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with AT21CS01-STUM-T (same form factor and footprint) — differing in Memory Size, Memory Type, Organization, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AT21CS01-STUM10-T
✅ Drop-In✓ In Stock
$0.26 / Unit
View Datasheet →AT21CS01-STUM11-T
✅ Drop-In📋 Reference alternative (not in catalog)
AT21CS01-STUM12-T
✅ Drop-In📋 Reference alternative (not in catalog)
AT21CS01-STUM13-T
✅ Drop-In📋 Reference alternative (not in catalog)
AT21CS01-STUM14-T
✅ Drop-In📋 Reference alternative (not in catalog)
AT21CS01-STUM15-T
✅ Drop-In📋 Reference alternative (not in catalog)
AT21CS11-STUM10-T
✅ Drop-In📋 Reference alternative (not in catalog)
AT21CS01-STUM-T Specifications
| Memory Type | Non-volatile EEPROM (Serial) |
| Memory Size | 1 Kbit (128 x 8 bits) |
| Organization | 128 words x 8 bits |
| Bus Interface | Single-Wire (SI/O) Serial |
| Operating Voltage Range | 1.7 V to 3.6 V |
| Standard-Speed Bit Rate | 15.4 kbps max (AT21CS01 only) |
| High-Speed Bit Rate | 125 kbps max |
| Write Cycle Support | 8-byte page write or single-byte write |
| Write Endurance | >1,000,000 cycles per location |
| Unique Serial Number | 64-bit factory-programmed |
| Discovery Response | Yes (quick device detection) |
| Operating Temperature Range | -40 C to +85 C |
| Package | SOT-23-3 (TO-236-3, SC-59) |
| Mounting Type | Surface Mount |
| Power Scheme | Parasitic (powered via SI/O pin) |
| External Pins Required | 2 (SI/O and GND) |
| RoHS Status | Compliant |
AT21CS01-STUM-T Pin Configuration
| Pin 1 | SI/O — Single Input/Output data line, also supplies parasitic power via internal charge pump |
| Pin 2 | GND — Ground reference |
| Pin 3 | NC — No internal connection (per Microchip datasheet DS20005857D) |
Typical Applications
AT21CS01-STUM-T is suitable for 7 applications: Ink and Toner Cartridge Identification, Analog Sensor Calibration Data Storage, After-Market Consumable Authentication, Medical Consumable Tracking, Cable and Accessory Authentication, Battery Pack Identification and Cycle Logging, Industrial Sensor Tagging.
Ink and Toner Cartridge Identification
The AT21CS01-STUM-T fits ink and toner cartridge identification because its 2-pin SI/O + GND interface matches the simplest possible cartridge contact pattern, and the integrated 64-bit factory serial number provides immediate anti-counterfeit verification. With 128 bytes of storage plus >1M write endurance, the host printer can rewrite cartridge counters thousands of times without wearing out the EEPROM. The parasitic power scheme means the cartridge needs no battery or external power - it is energized only when seated in the printer. The SOT-23-3 footprint (2.9 x 1.5 mm) fits even the smallest inkjet cartridges. Per Microchip datasheet DS20005857D, this exact use case is one of the explicitly targeted applications.
Recommended
Analog Sensor Calibration Data Storage
The AT21CS01-STUM-T is well suited to analog sensor calibration storage because the calibration coefficients, lot codes, and serial numbers can be written at factory calibration time and read back at each power-up over the SI/O pin. The >1M write endurance allows frequent recalibration during sensor life, while the 1.7-3.6V operating range directly matches low-voltage analog front-end rails. The unique factory-programmed 64-bit serial number supports traceability per unit. Per Microchip product documentation, analog sensor calibration storage is one of the explicit target use cases. Designers should reserve the first 8 bytes for the serial number and use the remaining 120 bytes for calibration tables and lot/date codes.
Recommended
After-Market Consumable Authentication
The AT21CS01-STUM-T supports after-market consumable authentication because its 64-bit unique serial number and 1 Kbit user memory can store signed certificates or rolling counters. The 2-pin interface is mechanically simple, enabling low-cost probe contacts on consumable housings. The device's parasitic power scheme means no battery is needed in the consumable, and >1M write endurance supports frequent rewrites of authentication counters. The 1.7-3.6V range is compatible with battery-powered host devices like blood-glucose meters, e-cigarettes, and water filters. Per Microchip datasheet DS20005857D, after-market consumable management is an explicitly targeted application.
Recommended
Medical Consumable Tracking
The AT21CS01-STUM-T is a strong fit for medical consumable tracking because the 2-pin SI/O + GND interface enables minimally invasive single-contact sterilization-compatible connections, while the 64-bit unique serial number ensures per-unit traceability required by FDA UDI regulations. The -40C to +85C operating range covers most medical device storage and use conditions. The 1.7-3.6V operating range matches the Li-ion battery rails common in portable medical devices. Per Microchip product documentation, this device is designed for unpowered attachments - a natural fit for disposable medical consumables like test strips, cartridges, and tubing sets.
Recommended
Cable and Accessory Authentication
The AT21CS01-STUM-T suits cable and accessory authentication because the 2-pin SI/O + GND interface matches standard 2-wire cable identification conventions. The factory 64-bit serial number prevents counterfeite-grade cables from emulating genuine accessories, and the 128 bytes of user memory can store cable specifications, length calibration, and supported features. The 1.7-3.6V operating range directly matches USB and accessory-detection voltages used in smartphones, laptops, and docking stations. The device's small SOT-23-3 package fits inside connector backshells.
Recommended
Battery Pack Identification and Cycle Logging
The AT21CS01-STUM-T fits battery pack identification because the 2-pin interface matches the simplest possible battery contact pattern and the >1M write endurance supports detailed cycle logging. Each charge/discharge cycle event can be written to EEPROM without wearing out the device for typical consumer battery lifetimes. The 64-bit unique serial number prevents counterfeite battery packs, which is a safety concern in high-energy Li-ion packs. The 1.7-3.6V operating range matches single-cell Li-ion/LiFePO4 rails. Per Microchip product documentation, the device is explicitly designed for unpowered attachments where it is energized only when in the host device.
Recommended
Industrial Sensor Tagging
The AT21CS01-STUM-T is suitable for industrial sensor tagging because its SOT-243 footprint and -40C to +85C operating range fit harsh industrial environments. The 64-bit unique serial number supports per-sensor traceability for calibration audit trails required by ISO 9001 quality systems. The 1.7-3.6V operating range matches 3.3V industrial bus rails (Modbus, IO-Link). The 2-pin interface simplifies field wiring in retrofit installations. Per Microchip datasheet DS20005857D, sensor calibration storage is one of the explicit target applications.
Recommended
Recommended Products Summary
Engineering reference data for AT21CS01-STUM-T — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AT21CS01-STUM10-T | AT21CS01-STUM11-T | AT21CS01-STUM12-T | AT21CS01-STUM15-T | AT21CS11-STUM10-T |
|---|---|---|---|---|---|---|
| Package | SOT-23-3 | SOT-23-3 - same | SOT-23-3 - same | SOT-23-3 - same | SOT-23-3 - same | SOT-23-3 - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Memory Size | 1 Kbit | 1 Kbit | 1 Kbit | 1 Kbit | 1 Kbit | 1 Kbit |
| Standard-Speed Mode (15.4 kbps) | Yes | Yes | Yes | Yes | Yes | No (High-Speed only) |
| High-Speed Mode (125 kbps) | Yes | Yes | Yes | Yes | Yes | Yes |
| Operating Voltage | 1.7 V to 3.6 V | 1.7 V to 3.6 V | 1.7 V to 3.6 V | 1.7 V to 3.6 V | 1.7 V to 3.6 V | 1.7 V to 3.6 V |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Factory Device Address | MPN-encoded (varies by suffix) | 000 | 001 | 010 | 100 | 000 (AT21CS11 die) |
Key Differentiators
- 2-pin parasitic-powered interface (SI/O + GND only) (vs AT24C02 (standard I2C EEPROM, 4 pins required: VCC, GND, SDA, SCL))
- Factory-programmed 64-bit unique serial number included (vs AT24C02 (no factory serial number))
- >1M write endurance per location (vs typical 100K-1M for I2C EEPROMs) (vs 24LC64-I/SN (1M write endurance typical))
- Discovery Response feature for fast device detection (vs AT21CS11-STUM10-T (lacks Standard-Speed mode and Discovery Response timing))
Design Notes
The AT21CS01-STUM-T only exposes SI/O (Pin 1), GND (Pin 2), and NC (Pin 3). Place the device near the edge of the PCB or contact pads since the SI/O pin doubles as the data and parasitic-power connection. Use a 2.1 kOhm to 10 kOhm pull-up resistor from SI/O to the host's 1.7V-3.6V rail, sized based on bus capacitance. Per Microchip datasheet DS20005857D, no VCC pin or decoupling capacitor is required.
The host MCU must drive the SI/O pin as an open-drain output with the internal pull-up disabled. A push-pull driver will damage the AT21CS01-STUM-T's internal charge pump. The reset/presence pulse requires the host to pull SI/O low for at least 480 us in Standard-Speed mode or 24 us in High-Speed mode per the Microchip datasheet - verify with an oscilloscope if communication fails at marginal bus lengths.
Do not assume the AT21CS01-STUM-T follows the Dallas/Maxim 1-Wire protocol - the command set and timing differ. Use the AT21CS01 firmware driver or community Arduino library, not a generic 1-Wire stack. Verify the factory device address in your MPN suffix to avoid bus collisions when multiple EEPROMs share one SI/O line - each address variant (STUM10-T through STUM16-T) addresses a different device on the bus.
Estimated: at 125 kbps High-Speed mode with a 2.1 kOhm pull-up, average SI/O line current draw is roughly 0.5 mA during reads (1.7V / 3.4 kOhm effective impedance). For battery hosts, switch to 10 kOhm pull-up when bus capacitance is below 50 pF to reduce quiescent draw. The AT21CS01-STUM-T does not enter a low-power sleep state; current draw scales with bus activity per Microchip datasheet DS20005857D.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified - this is a commercial/industrial grade EEPROM. Halogen-free per Microchip environmental compliance disclosures.
