Microchip Technology MCP795W21-I/SL

Overview

MCP795W21-I/SL from Microchip Technology is a battery-backed SPI Real-Time Clock/Calendar (RTCC) IC with integrated 2 Kbit EEPROM, EUI-48™ MAC address, programmable watchdog timer, dual event detect modules, and digital trimming. It maintains time to hundredth-of-second resolution across -40°C to +85°C, logs power-fail/power-up timestamps, and operates from 1.8V–3.6V main supply or 1.3V–3.6V backup. Used in industrial metering, smart sensors, and embedded systems requiring traceable time-stamping.

For engineers reviewing the MCP795W21-I/SL datasheet, MCP795W21-I/SL pinout, MCP795W21-I/SL application, or MCP795W21-I/SL equivalent, this page delivers verified specifications, validated pin functions, confirmed EUI-48™ identity storage, real-world timing accuracy (±1 ppm trim resolution), and direct alternative part comparisons - all grounded in DS20002280E.

Technical Context

The MCP795W21-I/SL implements a fully autonomous RTCC subsystem using a 32.768 kHz crystal oscillator with on-chip digital trimming (±1 ppm resolution, ±259 ppm range) and automatic switchover between VCC and VBAT. Its SPI interface supports up to 5 MHz clock rate at 2.5–3.6V and 3 MHz at 1.8–2.5V, with CS setup/hold times of 100 ns and data valid window of 100 ns.

It integrates three independent interrupt sources - dual alarms, high-speed/low-speed event detection, and watchdog timeout - each assignable to either IRQ or WDO open-drain outputs. The device maintains SRAM and RTCC registers during backup operation and logs precise timestamps for both power-loss and power-restoration events.

Key Specifications

Pinout & Package

14-pin SOIC (MCP795W21-I/SL) and TSSOP packages; both share identical pin mapping and thermal characteristics per DS20002280E.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar real-time clock/calendar applications.

Compared with MCP795W22-I/SL, the MCP795W21-I/SL offers EUI-48™ for compact MAC addressing and identical feature set at lower unit cost; versus DS3231M+, it trades marginal timing accuracy for integrated identity, event detection, and watchdog - delivering higher system-level integration with no layout changes.

Availability

MCP795W21-I/SL is available at Aetrix Electronics and suitable for smart energy metering, industrial sensor nodes, medical diagnostic devices, and programmable logic controllers requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for MCP795W21-I/SL 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 microcontrollers, analog components, and timing solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The MCP795Wxx family was designed to consolidate RTC, EEPROM, MAC identity, watchdog, and event detection into a single SPI-accessible IC - targeting industrial, medical, and infrastructure applications demanding robust timekeeping and system supervision.

FAQ

What is the primary function of the MCP795W21-I/SL?

The MCP795W21-I/SL is a battery-backed SPI Real-Time Clock/Calendar IC with integrated 2 Kbit EEPROM, EUI-48™ MAC address, programmable watchdog timer, dual event detect modules, and digital trimming. It maintains accurate time across -40°C to +85°C, logs power-fail/power-up events, and supports autonomous system supervision - all within a single 14-pin SOIC package. The MCP795W21-I/SL replaces discrete RTC, EEPROM, and watchdog ICs in resource-constrained embedded designs.

Does the MCP795W21-I/SL include factory-programmed identification?

Yes, the MCP795W21-I/SL includes a factory-programmed 48-bit EUI-48™ MAC address stored in its protected 128-bit EEPROM area. This identifier is prewritten and locked with a robust unlock sequence, making it suitable for secure network node identification in Ethernet or Wi-Fi-enabled devices. The MCP795W21-I/SL does not contain EUI-64™ - that variant is the MCP795W22-I/SL.

How does the MCP795W21-I/SL handle power transitions between VCC and VBAT?

The MCP795W21-I/SL automatically switches to VBAT backup supply when VCC drops below the 1.3–1.7V VTRIP window, maintaining RTCC operation and SRAM contents without interruption. It logs precise timestamps for both power-loss and power-restoration events in dedicated registers (0x18–0x1F). The MCP795W21-I/SL resumes normal VCC operation once voltage exceeds VTRIP, with no software intervention required.

What are the key timing accuracy features of the MCP795W21-I/SL?

The MCP795W21-I/SL achieves high timing accuracy through an optimized 32.768 kHz crystal oscillator circuit supporting 6–9 pF load capacitance crystals, plus on-chip digital trimming with ±1 ppm resolution over a ±259 ppm range. It compensates for leap years through 2399 and supports both 12- and 24-hour formats. The MCP795W21-I/SL maintains hundredth-of-second resolution and retains accuracy during VBAT operation with typical 1.0 µA backup current at 3.0V.

Can the MCP795W21-I/SL generate clock outputs or interrupts for external use?

Yes, the MCP795W21-I/SL provides two dedicated open-drain interrupt outputs - IRQ and WDO - each configurable to assert on alarm, event detect, or watchdog timeout. It also features CLKOUT, a programmable square-wave output supporting frequencies from 1 Hz to 32.768 kHz. All three outputs (IRQ, WDO, CLKOUT) are independently configurable and require external pull-up resistors. The MCP795W21-I/SL supports simultaneous use of these outputs without functional conflict.