Microchip Technology MCP795W12T-I/SL

Overview

MCP795W12T-I/SL 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 metering, medical data loggers, and smart utility endpoints.

For engineers reviewing the MCP795W12T-I/SL datasheet, MCP795W12T-I/SL pinout, MCP795W12T-I/SL application, or MCP795W12T-I/SL equivalent, key selection criteria include its EUI-64™ preprogrammed address, dual programmable alarms, 14-pin SOIC/TSSOP package with EVHS/EVLS event inputs, and guaranteed 1.0 µA timekeeping current from VBAT at 3.0V.

Technical Context

The MCP795W12T-I/SL implements a 32.768 kHz crystal oscillator with on-chip digital trimming (±259 ppm range, ±1 ppm resolution) optimized for 6–9 pF load capacitance crystals. Its SPI interface operates up to 5 MHz (VCC ≥ 2.5V) and supports MSb-first transfers with CS-active-low protocol.

Timekeeping logic uses BCD-encoded registers (0x00–0x1F) buffered during reads to prevent rollover errors; leap-year compensation covers years 2001–2399. Power-fail timestamping captures switchover events to/from battery mode, while the dedicated WDO and IRQ open-drain outputs support configurable alarm, watchdog, and event interrupt routing.

Key Specifications

Pinout & Package

Package: 14-lead SOIC (MCP795W12T-I/SL) and TSSOP - both RoHS-compliant, moisture-sensitive level 3, rated for industrial temperature operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP795W11T-I/SL, the MCP795W12T-I/SL delivers future-proof EUI-64™ identity for IoT scalability; versus DS3231M+, it trades TCXO-grade accuracy for richer peripheral integration (SPI, dual event inputs, WDO, alarms) in a single chip.

Availability

MCP795W12T-I/SL is available at Aetrix Electronics and suitable for industrial metering, medical data loggers, and IoT edge gateways requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MCP795W12T-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 product line was designed for embedded systems requiring autonomous, battery-backed timekeeping with integrated system supervision - targeting applications where MCU offload, secure identity, and event-aware timing are critical.

FAQ

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

The MCP795W12T-I/SL serves as a standalone Real-Time Clock/Calendar (RTCC) that maintains accurate time and date across power cycles using battery backup. It integrates 1 Kbit EEPROM, 64-byte SRAM, dual alarms, a watchdog timer, and two event-detect inputs - enabling it to replace multiple discrete functions in industrial and medical systems. The MCP795W12T-I/SL specifically includes factory-programmed EUI-64™ addressing for secure device identity in networked applications.

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

The MCP795W12T-I/SL automatically switches to VBAT when VCC drops below 1.5V (typical), preserving RTCC operation and SRAM contents without host intervention. It logs exact timestamps for both power-fail and power-up events into dedicated registers (0x18–0x1F). The MCP795W12T-I/SL draws only 1.0 µA from VBAT at 3.0V, supporting multi-year operation on standard coin cells - verified across -40°C to +85°C.

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

Yes, the MCP795W12T-I/SL supports external 32.768 kHz clock input on the X1 pin. To enable this mode, the EXTOSC bit in the CONTROL register (address 0x08) must be set, and X2 must be left floating. Crystal mode remains active by default (ST bit set in RTCSEC register). Both configurations retain full functionality including digital trimming, alarms, and timestamping - but external clock bypasses crystal load capacitor requirements and oscillator stability dependencies.

What memory resources are available on the MCP795W12T-I/SL and how are they protected?

The MCP795W12T-I/SL provides 64-byte battery-backed SRAM (0x20–0x5F), 1 Kbit software-write-protected EEPROM (page write up to 8 bytes), and 128-bit protected EEPROM preprogrammed with EUI-64™. Write access to the protected block requires a robust unlock sequence (UNLOCK instruction followed by IDWRITE); standard EEPROM supports software write-disable via STATUS register bits. All memory retains data during VCC loss when VBAT is present.

How are the dual event detection modules configured and used in practice?

The MCP795W12T-I/SL includes EVHS (high-speed) and EVLS (low-speed) inputs, each with independent configuration registers. EVHS detects programmable pulse counts (e.g., encoder ticks or communication frames) and asserts IRQ on completion. EVLS applies selectable debounce periods (1 ms to 256 ms) to mechanical switch inputs - eliminating external RC filters. Both modules generate interrupts that persist until cleared via EVDTCON register, and their flags are readable in real time without affecting RTCC operation.