Microchip Technology MCP795W12-I/ST

Overview

MCP795W12-I/ST from Microchip Technology is a battery-backed SPI Real-Time Clock/Calendar (RTCC) IC with integrated 1 Kbit EEPROM, 64-byte SRAM, EUI-64™ MAC address, programmable watchdog timer, dual event detect modules, and digital trimming. It operates from 1.8V–3.6V, draws 1.2 µA timekeeping current at 3.0V from V_CC, and maintains time/date across power loss via automatic V_CC/V_BAT switchover - used in industrial metering, medical logging, and smart sensor nodes.

For engineers reviewing the MCP795W12-I/ST datasheet, MCP795W12-I/ST pinout, MCP795W12-I/ST application, or MCP795W12-I/ST equivalent, key selection criteria include ±1 ppm digital trim resolution, power-fail timestamp logging, dual alarms with flexible masking, 5 MHz SPI interface, and EUI-64™ preprogrammed identity for secure device identification in networked embedded systems.

Technical Context

The MCP795W12-I/ST implements a fully autonomous RTCC using a 32.768 kHz crystal oscillator with on-chip digital trimming (±259 ppm range, ±1 ppm resolution) and oscillator failure detection (OSCRUN flag). Its SPI interface supports up to 5 MHz clock rate with strict timing margins (e.g., 100 ns CS setup at 2.5–3.6V).

It integrates three independent interrupt sources - dual alarms, high-speed/low-speed event detect modules - all assignable to either IRQ or WDO pins. Power management includes automatic switchover at 1.3–1.7 V_TRIP, backup current as low as 1.0 µA at 3.0V V_BAT, and timestamp capture of both power-down and power-up events.

Key Specifications

Pinout & Package

14-pin SOIC (MCP795W12-I/ST) and TSSOP packages; RoHS-compliant, lead-free finish; body dimensions 8.65 mm × 3.90 mm × 1.75 mm (SOIC).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP795W11-I/ST, the MCP795W12-I/ST provides expanded 64-bit identity for modern IP networking and enhanced security; versus DS3231SN#T&R, it trades raw oscillator stability for richer peripheral integration (SPI, dual alarms, event detect, 1 Kbit EEPROM) in resource-constrained microcontroller systems.

Availability

MCP795W12-I/ST is available at Aetrix Electronics and suitable for industrial metering, medical data loggers, and secure IoT gateways requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MCP795W12-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 microcontrollers, analog components, and timing solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The MCP795Wxx family is designed for embedded systems requiring autonomous, battery-backed timekeeping with integrated memory, event handling, and secure identity - targeting smart energy, healthcare, and industrial connectivity applications.

FAQ

What is the primary function of the MCP795W12-I/ST?

The MCP795W12-I/ST is a SPI-interfaced Real-Time Clock/Calendar IC that maintains accurate time and date (including leap year compensation to 2399), logs power-fail events, stores data in 64-byte SRAM and 1 Kbit EEPROM, and provides factory-programmed EUI-64™ identity. Its core function is autonomous, low-power timekeeping with integrated system supervision features like watchdog and event detection - all within the MCP795W12-I/ST device.

Does the MCP795W12-I/ST support external crystal oscillators?

Yes, the MCP795W12-I/ST supports external 32.768 kHz tuning fork crystals on X1/X2 pins with optimized drive circuitry for 6–9 pF load capacitance. It also allows external clock input on X1 (with X2 floating) when the EXTOSC bit is set. Oscillator health is monitored via the OSCRUN flag in RTCWKDAY register, and digital trimming (±1 ppm steps) compensates for crystal variance - confirmed in the MCP795W12-I/ST datasheet Section 5.2.

How does the power-fail timestamp feature work in the MCP795W12-I/ST?

The MCP795W12-I/ST automatically captures and stores the exact time of V_CC loss (power-down timestamp) and V_CC restoration (power-up timestamp) in dedicated registers (0x18–0x1B and 0x1C–0x1F). This occurs without host intervention during switchover between V_CC and V_BAT, using the internal timebase. The timestamps are retained in battery-backed memory and readable via SPI - a defining capability of the MCP795W12-I/ST for reliability diagnostics.

What memory resources are included in the MCP795W12-I/ST?

The MCP795W12-I/ST integrates 64 bytes of battery-backed SRAM (0x20–0x5F), 1 Kbit (128-byte) software-write-protected EEPROM (accessible via EEREAD/EEWRITE), and 128 bits (16-byte) of protected EEPROM preprogrammed with EUI-64™ (accessible via IDREAD/IDWRITE after unlock). All memory remains functional during V_BAT-only operation - verified in MCP795W12-I/ST memory map (Figure 5-1) and Section 5.1.

Can the MCP795W12-I/ST generate clock outputs?

Yes, the MCP795W12-I/ST provides a configurable CLKOUT pin (Pin 13) capable of outputting a square wave at 32.768 kHz or divided frequencies (1 Hz, 64 Hz, 128 Hz, 256 Hz, 512 Hz, 1024 Hz, 2048 Hz, 4096 Hz) selected via SQWFS[1:0] bits in CONTROL register. The output is enabled by setting SQWEN and disabled by clearing it - a hardware-controlled feature independent of SPI activity in the MCP795W12-I/ST.