Microchip Technology MCP795W20-I/SL

Overview

MCP795W20-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 MCP795W20-I/SL datasheet, MCP795W20-I/SL pinout, MCP795W20-I/SL application, or MCP795W20-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 MCP795W20-I/SL implements a fully autonomous RTCC with leap-year compensation through 2399, 12/24-hour mode selection, and BCD-encoded time registers. Its on-chip oscillator supports 6–9 pF crystals and includes digital trimming (±259 ppm range, ±1 ppm resolution) for long-term accuracy calibration.

It integrates two independent event detection paths: high-speed pulse counting (EVHS) and low-speed mechanical switch debouncing (EVLS), each with configurable interrupt outputs. The dedicated WDO pin delivers user-selectable watchdog timeout pulses, while IRQ serves as a shared interrupt output for alarms and event modules.

Key Specifications

Pinout & Package

Package: 14-lead SOIC (Small Outline Integrated Circuit), 3.9 mm × 8.7 mm body, 1.27 mm pitch, RoHS-compliant.

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 MCP795W20-I/SL omits factory-programmed EUI-64™ but retains full functional compatibility; versus DS3231M+, it trades absolute accuracy for richer peripheral integration and SPI flexibility - making it optimal for resource-constrained embedded designs needing multiple time-triggered functions.

Availability

MCP795W20-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 MCP795W20-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 microcontroller, mixed-signal, analog, and Flash-IP solutions, headquartered in Chandler, Arizona.

The MCP795Wxx family is designed for embedded systems requiring autonomous, battery-backed timekeeping with integrated peripherals - targeting industrial, medical, and infrastructure applications where reliability and feature density outweigh raw accuracy.

FAQ

What is the primary function of the MCP795W20-I/SL in an embedded system?

The MCP795W20-I/SL serves as a self-contained Real-Time Clock/Calendar (RTCC) with integrated watchdog timer, event detection, and nonvolatile memory. Its primary function is to maintain accurate time and date across power cycles using battery backup, while providing programmable alarms, timestamped power transitions, and SPI-accessible 2 Kbit EEPROM and 64-byte SRAM - all within the MCP795W20-I/SL die.

Does the MCP795W20-I/SL support external 32.768 kHz clock input, and how is it enabled?

Yes, the MCP795W20-I/SL supports external 32.768 kHz clock input on the X1 pin. It is enabled by setting the EXTOSC bit (bit 4) in the CONTROL register (address 0x08). When EXTOSC = 1, the internal crystal oscillator is disabled and X1 accepts an external CMOS-level clock signal; X2 must be left floating in this mode. This configuration is confirmed for the MCP795W20-I/SL in DS20002280E.

How does the power-fail timestamp feature work in the MCP795W20-I/SL?

The MCP795W20-I/SL automatically logs the exact time of VCC loss (power-down timestamp) and VCC restoration (power-up timestamp) into dedicated register blocks (0x18–0x1B and 0x1C–0x1F). These timestamps are captured during switchover to and from VBAT, using the same RTCC counters that track time - ensuring traceability of power events without host MCU intervention. This behavior is intrinsic to the MCP795W20-I/SL architecture.

What is the difference between MCP795W20-I/SL and MCP795W22-I/SL?

The MCP795W20-I/SL and MCP795W22-I/SL share identical RTCC, EEPROM, SRAM, and peripheral functionality, and are pin-compatible in 14-lead SOIC. The sole difference is that MCP795W22-I/SL has its 128-bit protected EEPROM preprogrammed with an EUI-64™ MAC address, whereas MCP795W20-I/SL ships with blank protected EEPROM. All other electrical and timing specifications match exactly for both variants.

Can the MCP795W20-I/SL operate from a 1.8V supply, and what are the timing implications?

Yes, the MCP795W20-I/SL operates across 1.8V to 3.6V VCC. At 1.8V, SPI clock frequency is limited to 3 MHz (vs. 5 MHz at ≥2.5V), and AC timing parameters such as TCSS, TCSH, TSU, and THD increase by ~50% per DS20002280E Table 1-2. The 1.2 µA typical timekeeping current (D12) is specified at 1.8V, confirming full functionality across the entire voltage range for the MCP795W20-I/SL.