Microchip Technology MCP795W20T-I/SL

Overview

MCP795W20T-I/SL from Microchip Technology is a battery-backed SPI Real-Time Clock/Calendar (RTCC) IC with integrated watchdog timer, dual event detect modules, 2 Kbit EEPROM, and 64-byte SRAM. It maintains time to hundredth-of-second resolution across -40°C to +85°C, supports 32.768 kHz crystal or external clock input, and logs power-fail/power-up timestamps. Used in industrial control panels requiring precise, nonvolatile timekeeping under intermittent power.

For engineers reviewing the MCP795W20T-I/SL datasheet, MCP795W20T-I/SL pinout, MCP795W20T-I/SL application, or MCP795W20T-I/SL equivalent, key selection criteria include ±1 ppm digital trimming range, 1.0 µA VBAT timekeeping current, dual programmable alarms, SPI interface up to 5 MHz, and EUI-64™ address support - all confirmed for this exact 14-pin SOIC variant.

Technical Context

The MCP795W20T-I/SL implements a fully autonomous RTCC with BCD-encoded time registers (hundredths of seconds through year), leap-year compensation to 2399, and 12/24-hour mode selection. Its oscillator supports both 32.768 kHz crystals (6–9 pF load) and external clock input via X1, with OSCRUN status flag and TOSF = 1 ms timeout detection.

Power management includes automatic switchover at VTRIP = 1.3–1.7 V between VCC (1.8–3.6 V) and VBAT (1.3–3.6 V), preserving SRAM and RTC state. The device integrates two independent event detectors: high-speed pulse counter (EVHS) and low-speed switch debouncer (EVLS), each with configurable interrupt outputs routed to IRQ or WDO pins.

Key Specifications

Pinout & Package

14-pin SOIC package (3.90 mm × 8.65 mm, 1.27 mm pitch), RoHS-compliant, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP795W20T-I/SL, MCP795W21T-I/SL provides identical RTC functionality with different MAC addressing, while RV-3028-C7 trades integrated peripherals and SPI for extreme low-power operation and I²C simplicity - neither offers pin-compatible replacement without firmware or layout review.

Availability

MCP795W20T-I/SL is available at Aetrix Electronics and suitable for industrial control panels, smart energy meters, medical diagnostic devices, and building automation controllers requiring stable component supply and long-term lifecycle support.

Supply support for MCP795W20T-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 delivers highly integrated, battery-backed RTCs with enhanced system-level features - designed specifically for industrial, medical, and infrastructure applications demanding precision timekeeping, data integrity, and robust power management.

FAQ

What is the crystal load capacitance requirement for MCP795W20T-I/SL?

The MCP795W20T-I/SL is optimized for 32.768 kHz tuning fork crystals with a specified load capacitance of 6–9 pF. External load capacitors CX1 and CX2 must be selected to match the crystal's CL specification, accounting for PCB stray capacitance. Crystals rated for 12.5 pF are not recommended. The device's internal oscillator circuitry and digital trimming ensure stable operation across temperature and voltage variations when properly configured.

Does MCP795W20T-I/SL support both 12-hour and 24-hour time formats?

Yes, MCP795W20T-I/SL supports both 12-hour and 24-hour time formats. The format is selected via the 12/24 bit in the RTCHOUR register (address 0x03), and this setting applies consistently across all time registers and alarm configurations. The AM/PM bit is active only in 12-hour mode and is stored in the same register. All time values are maintained in binary-coded decimal (BCD) format for direct microcontroller interpretation without software conversion.

How does the power-fail timestamp function work in MCP795W20T-I/SL?

The MCP795W20T-I/SL automatically logs the exact time of VCC switchover to VBAT (power-down timestamp) and VCC restoration (power-up timestamp) into dedicated register blocks (addresses 0x18–0x1B and 0x1C–0x1F). These timestamps are captured in real time using the active RTCC counters and remain accessible after power recovery. No host intervention is required - the feature operates autonomously upon detection of VTRIP crossing (1.3–1.7 V), enabling post-mortem analysis of power events without external supervision.

Can MCP795W20T-I/SL operate without an external crystal?

Yes, MCP795W20T-I/SL can operate without an external crystal by configuring the EXTOSC bit in the CONTROL register to accept a 32.768 kHz external clock signal applied to the X1 pin. In this mode, X2 is left floating. The device retains full RTCC functionality, including timekeeping, alarms, and timestamping. Crystal oscillator mode remains disabled until the ST bit is set, allowing flexible design-in for systems with existing clock sources or stringent EMI constraints.

What is the purpose of the protected EEPROM block in MCP795W20T-I/SL?

The 128-bit protected EEPROM block in MCP795W20T-I/SL stores factory-programmed EUI-64™ MAC address and supports secure custom data storage. Access requires a robust two-step unlock sequence (UNLOCK instruction followed by IDWRITE), preventing accidental or malicious overwrites. This area is ideal for storing immutable identifiers, cryptographic keys, or calibration constants that must survive repeated power cycles and firmware updates - distinct from the main 2 Kbit EEPROM used for application data.