Microchip Technology MCP795W12T-I/ST

Overview

MCP795W12T-I/ST from Microchip Technology is a battery-backed SPI Real-Time Clock/Calendar (RTCC) IC with integrated watchdog timer, dual event detect modules, 1 Kbit EEPROM, and 64-byte SRAM. It maintains time to hundredth-of-second resolution across -40°C to +85°C, supports ±1 ppm digital trimming, logs power-fail/power-up timestamps, and operates from 1.8V–3.6V main supply or 1.3V–3.6V backup supply. Used in industrial control panels requiring precise timestamping and fail-safe timekeeping.

For engineers reviewing the MCP795W12T-I/ST datasheet, MCP795W12T-I/ST pinout, MCP795W12T-I/ST application, or MCP795W12T-I/ST equivalent, key selection criteria include its EUI-64™-preprogrammed protected EEPROM, dual programmable alarms assignable to IRQ or WDO pins, 1.0 µA VBAT timekeeping current at 3.0V, and 14-pin SOIC/TSSOP package with verified SPI interface up to 5 MHz.

Technical Context

The MCP795W12T-I/ST implements a fully autonomous RTCC using an internal 32.768 kHz oscillator circuit optimized for 6–9 pF crystals, with on-chip digital trimming (±259 ppm range, ±1 ppm resolution) and automatic oscillator failure detection via OSCRUN flag. Its SPI interface complies with standard mode-0 timing, supporting up to 5 MHz clock rate at VCC ≥ 2.5V and 3 MHz at 1.8V ≤ VCC < 2.5V.

Power management includes seamless switchover between VCC and VBAT at 1.5V typical trip point, with independent timekeeping current paths: 1.2 µA from VCC at 3.0V and 1.0 µA from VBAT at 3.0V. The device integrates two event-detect modules - high-speed pulse counter and low-speed switch debouncer - each with configurable interrupt outputs routed to IRQ or WDO pins.

Key Specifications

Pinout & Package

Package: 14-lead SOIC (MCP795W12T-I/ST) and TSSOP; RoHS-compliant, moisture-sensitive level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP795W11T-I/ST and MCP795W22T-I/ST, the MCP795W12T-I/ST uniquely balances EUI-64™ network identity with 1 Kbit of protected EEPROM-making it optimal for IPv6-capable embedded gateways where compact size and standardized addressing outweigh extra EEPROM capacity.

Availability

MCP795W12T-I/ST is available at Aetrix Electronics and suitable for industrial control panels, smart energy meters, medical infusion pumps, and building automation controllers requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for MCP795W12T-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, FPGA, and timing solutions, serving automotive, industrial, consumer, and communications markets with vertically integrated silicon and development tools.

The MCP795Wxx product line delivers highly integrated, battery-backed SPI RTCs with enhanced reliability features-including power-fail timestamping, dual alarms, and EUI programming-for applications demanding deterministic timekeeping and secure device identity in harsh environments.

FAQ

What is the primary function of the MCP795W12T-I/ST in a system design?

The MCP795W12T-I/ST serves as a standalone, battery-backed Real-Time Clock/Calendar (RTCC) with integrated watchdog timer and event detection. It maintains accurate time across power cycles, logs power-fail/power-up events, and provides programmable alarms and clock outputs-enabling reliable timestamping, system supervision, and scheduling without host MCU intervention. Its EUI-64™ address supports secure network identification in the MCP795W12T-I/ST.

How does the MCP795W12T-I/ST handle power transitions between VCC and VBAT?

The MCP795W12T-I/ST automatically switches to VBAT when VCC drops below 1.5V typical (1.3V–1.7V range), preserving RTCC operation and SRAM contents. It logs exact timestamps of both power-loss and power-restoration events in dedicated registers (0x18–0x1F). Timekeeping current remains at 1.0 µA typical from VBAT at 3.0V, ensuring multi-year backup operation. This behavior is intrinsic to the MCP795W12T-I/ST's power-control architecture.

Can the MCP795W12T-I/ST use an external clock instead of a crystal?

Yes-the MCP795W12T-I/ST supports external 32.768 kHz clock input via the X1 pin. When enabled by setting the EXTOSC bit in the CONTROL register, the internal crystal oscillator is disabled and X2 is left floating. This mode bypasses crystal load capacitance matching and oscillator stability concerns, making the MCP795W12T-I/ST suitable for systems with shared precision clock sources or stringent EMI requirements.

What memory resources are available on the MCP795W12T-I/ST?

The MCP795W12T-I/ST includes 64 bytes of battery-backed SRAM (0x20–0x5F), 1 Kbit of software-write-protected EEPROM (accessible via EEREAD/EEWRITE), and 128 bits of protected EEPROM preprogrammed with EUI-64™ (accessible via IDREAD/IDWRITE). All memory blocks retain data during VCC loss and are accessed via distinct SPI instruction sets-ensuring isolation and security for critical identifiers in the MCP795W12T-I/ST.

How are alarms configured and routed on the MCP795W12T-I/ST?

Two independent alarms (ALM0 and ALM1) are configured via dedicated registers (0x0C–0x17) with maskable fields from hundredths-of-seconds to month. Each alarm's output can be assigned to either the IRQ pin (open-drain, active-low interrupt) or WDO pin (open-drain, user-selectable pulse width) via CONTROL register bits ALM0PIN/ALM1PIN. This routing flexibility allows the MCP795W12T-I/ST to drive different system responses-such as MCU wake-up or hardware reset-without external logic.