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Home > Products > Integrated Circuits (ICs) > Clock/Timing > Real Time Clocks

Microchip Technology MCP795W20-I/ST

Name: MCP795W20-I/ST
Brand: Microchip Technology
SKU: MCP795W20-I/ST
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MCP795W20-I/ST

Manufacturer:: Microchip Technology

Category:: Real Time Clocks

Package:: 14-TSSOP (0.173", 4.40mm Width)

Datasheet:: MCP795W20-I/ST.pdf

Description:: IC RTC CLK/CALENDAR SPI 14TSSOP

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Product details

Overview

MCP795W20-I/ST from Microchip Technology is a battery-backed SPI Real-Time Clock/Calendar (RTCC) IC with 2 Kbit EEPROM, dual alarms, programmable watchdog timer, and power-fail timestamp logging. It operates from 1.8V–3.6V, draws 1.2 µA at 3.0V V_CC, supports ±1 ppm digital trimming, and maintains time across primary-to-battery switchover in industrial temperature range (−40°C to +85°C). Used in smart meters, industrial controllers, and data loggers requiring precise, persistent timekeeping.

For engineers reviewing the MCP795W20-I/ST datasheet, MCP795W20-I/ST pinout, MCP795W20-I/ST application, or MCP795W20-I/ST equivalent, key selection criteria include its 14-pin SOIC/TSSOP package, SPI interface up to 5 MHz, 32.768 kHz crystal optimization (6–9 pF), 64-byte SRAM, and EUI-64™-ready protected EEPROM - all validated for long-term backup operation down to 1.3V V_BAT.

Technical Context

The MCP795W20-I/ST integrates a low-power 32.768 kHz oscillator with on-chip digital trimming (±259 ppm range, ±1 ppm resolution) and automatic switchover between V_CC and V_BAT at 1.3–1.7 V. Its RTCC engine tracks hundredth-of-seconds through year (leap-year compensated to 2399) in BCD format and supports both 12- and 24-hour modes.

It features two independent event detect modules - high-speed pulse counting and low-speed switch debouncing - plus dual programmable alarms assignable to IRQ or WDO pins. The dedicated WDO pin outputs configurable low pulses for watchdog timeout or alarm events, while CLKOUT delivers selectable square-wave frequencies.

Key Specifications

Parameter	Value and Actual Design Meaning
Timekeeping Accuracy	±1 ppm resolution via digital trim; enables <1 sec/month drift correction after crystal tolerance and temp compensation
Backup Current	1.0 µA typical at 3.0V V_BAT; ensures >10-year coin-cell operation in always-on timekeeping mode
SPI Speed	Up to 5 MHz (≥2.5V V_CC); supports fast register access and bulk EEPROM writes without MCU bottleneck
EEPROM Size	2 Kbit (256 bytes) software write-protected; stores firmware logs, calibration data, or configuration without external memory
Oscillator Support	Optimized for 6–9 pF 32.768 kHz crystals; eliminates need for external load caps in many designs
Power-Fail Timestamp	Logs exact time of V_CC loss and restoration; critical for forensic power-event analysis in industrial systems
Protected EEPROM	128-bit area with robust unlock sequence; holds EUI-64™ MAC address or security keys with tamper-resistant write control

Pinout & Package

Package: 14-pin SOIC (MCP795W20-I/ST) and TSSOP - both RoHS-compliant, surface-mount, 1.27 mm pitch.

Pin/Terminal	Circuit Role	Design Meaning
X1	Crystal input / external clock input	Accepts 32.768 kHz crystal or buffered clock signal; enables oscillator bypass mode when EXTOSC=1
X2	Crystal output	Drives crystal resonator; must be left floating if external clock used
VBAT	Backup supply input	Provides power to RTCC and SRAM during main supply loss; operates down to 1.3V
WDO	Watchdog/alarm open-drain output	Asserts low pulse on timeout or alarm trigger; requires external pull-up to V_CC or V_BAT
IRQ	Interrupt open-drain output	Signals event detect or alarm activation; remains low until flag cleared in STATUS register
CS	Chip select input	Active-low SPI enable; initiates instruction decode on high-to-low transition after power-up
VSS	Ground reference	Common return for analog/digital domains; must be low-impedance connection to minimize noise coupling
SO	SPI serial data output	Tri-states when CS high; outputs MSB-first data synchronized to SCK falling edge
SI	SPI serial data input	Latches instruction/address/data on SCK rising edge; supports standard SPI mode 0/3
SCK	SPI clock input	Drives internal timing; max 5 MHz rate at ≥2.5V V_CC; rise/fall times ≤100 ns
EVHS	High-speed event input	Detects up to 1 MHz pulses; generates interrupt after programmable count; tie to V_SS/V_CC if unused
EVLS	Low-speed event input	Debounces mechanical switches with user-selectable period; prevents false triggers from contact bounce
CLKOUT	Configurable clock output	Delivers 32.768 kHz, 1 Hz, or other divided frequencies; can serve as system clock source or debug signal
VCC	Main power supply	1.8–3.6V operation; powers EEPROM write cycles, SPI interface, and active RTCC functions

Key Features

Feature	Design Value
Dual programmable alarms	Independent alarm registers (ALM0/ALM1) support maskable comparison on all time/date fields - enables scheduled wake-up or maintenance alerts
Power-fail timestamp	Automatically logs exact time of V_CC dropout and recovery in dedicated PWRDN/PWRUP registers - provides auditable power-event history
On-chip digital trimming	±259 ppm adjustment range with ±1 ppm resolution - corrects crystal aging and temperature drift without external components
Event detect modules	Separate EVHS (pulse counting) and EVLS (debounce) inputs eliminate need for external logic or firmware polling - reduces MCU overhead
Protected 128-bit EEPROM	Write-locked area requiring multi-step unlock sequence - secures EUI-64™ MAC address or cryptographic keys against accidental overwrite
Automatic V_CC/V_BAT switchover	Seamless transition at 1.3–1.7 V threshold with no glitch or reset - preserves real-time continuity during brownouts or battery swaps

Applications

Smart Energy Metering	Industrial PLC Controller
Use Scenario: Utility-grade electricity meter recording kWh consumption with tariff-based billing tied to precise time-of-use windows. IC Role / Device Role / Timing Role: Primary RTCC providing UTC-synchronized timestamps for energy accumulation registers and secure firmware update validation. Use Value: Power-fail timestamp ensures accurate billing continuity during grid outages; ±1 ppm trim enables compliance with IEC 62053-21 Class 0.5S accuracy requirements.	Use Scenario: Programmable logic controller managing factory automation sequences where cycle timing, maintenance scheduling, and event logging depend on stable timebase. IC Role / Device Role / Timing Role: Standalone timekeeper offloading time-critical tasks from main MCU; dual alarms trigger preventive maintenance routines. Use Value: 64-byte SRAM retains runtime counters and state variables during power loss; 2 Kbit EEPROM stores calibration offsets and operational logs without external memory.
Medical Data Logger	Networked Building Controller
Use Scenario: Portable patient monitor capturing vital signs with ISO 13485-compliant audit trail including timestamped sensor readings and alarm events. IC Role / Device Role / Timing Role: Tamper-evident time source feeding into secure logging subsystem; protected EEPROM stores device identity and regulatory certificates. Use Value: EUI-64™-ready 128-bit protected EEPROM meets FDA 21 CFR Part 11 electronic record integrity requirements; battery backup ensures traceability across battery changes.	Use Scenario: HVAC controller coordinating zone temperatures, occupancy schedules, and energy reporting across distributed building management network. IC Role / Device Role / Timing Role: Central time coordinator synchronizing local actuators and upstream BACnet/IP gateways; CLKOUT drives secondary timing domains. Use Value: Dual event detect inputs debounce thermostat buttons and sense door/window status; low 1.2 µA V_CC current extends battery life in wireless sensor nodes.

Smart Energy Metering

Industrial PLC Controller

Use Scenario: Utility-grade electricity meter recording kWh consumption with tariff-based billing tied to precise time-of-use windows.

IC Role / Device Role / Timing Role: Primary RTCC providing UTC-synchronized timestamps for energy accumulation registers and secure firmware update validation.

Use Value: Power-fail timestamp ensures accurate billing continuity during grid outages; ±1 ppm trim enables compliance with IEC 62053-21 Class 0.5S accuracy requirements.

Use Scenario: Programmable logic controller managing factory automation sequences where cycle timing, maintenance scheduling, and event logging depend on stable timebase.

IC Role / Device Role / Timing Role: Standalone timekeeper offloading time-critical tasks from main MCU; dual alarms trigger preventive maintenance routines.

Use Value: 64-byte SRAM retains runtime counters and state variables during power loss; 2 Kbit EEPROM stores calibration offsets and operational logs without external memory.

Medical Data Logger

Networked Building Controller

Use Scenario: Portable patient monitor capturing vital signs with ISO 13485-compliant audit trail including timestamped sensor readings and alarm events.

IC Role / Device Role / Timing Role: Tamper-evident time source feeding into secure logging subsystem; protected EEPROM stores device identity and regulatory certificates.

Use Value: EUI-64™-ready 128-bit protected EEPROM meets FDA 21 CFR Part 11 electronic record integrity requirements; battery backup ensures traceability across battery changes.

Use Scenario: HVAC controller coordinating zone temperatures, occupancy schedules, and energy reporting across distributed building management network.

IC Role / Device Role / Timing Role: Central time coordinator synchronizing local actuators and upstream BACnet/IP gateways; CLKOUT drives secondary timing domains.

Use Value: Dual event detect inputs debounce thermostat buttons and sense door/window status; low 1.2 µA V_CC current extends battery life in wireless sensor nodes.

Equivalent & Alternatives

The following parts are listed as comparable options for similar RTC/calendar applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MCP795W21-I/ST	Same die, preprogrammed with EUI-48™ MAC address instead of EUI-64™; identical pinout, timing, and memory map	Required where IEEE 802.3/Ethernet MAC addressing is mandated over IPv6-ready EUI-64™	Select MCP795W21-I/ST only if legacy MAC format is required; otherwise MCP795W20-I/ST offers broader IPv6 compatibility
DS3231SN#T&R	Higher accuracy (±2 ppm TCXO), integrated temperature-compensated oscillator; no event detect or watchdog; 235 nA backup current	Better suited for ultra-low-power portable devices where precision outweighs feature count; lacks SPI EEPROM and event inputs	Choose DS3231SN#T&R when sub-2 ppm accuracy and minimal backup current are critical; MCP795W20-I/ST preferred when system-level integration (alarms, WDT, EEPROM) reduces BOM cost

Compared with MCP795W21-I/ST, the MCP795W20-I/ST provides EUI-64™ addressing for modern IP networking stacks, while versus DS3231SN#T&R it trades absolute accuracy for on-chip intelligence (dual alarms, event detection, programmable WDT) that eliminates discrete support components in resource-constrained embedded designs.

Availability

MCP795W20-I/ST is available at Aetrix Electronics and suitable for smart metering, industrial PLCs, medical data loggers, and networked building controllers requiring stable component supply across extended product lifecycles.

Supply support for MCP795W20-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 devices, and timing solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The MCP795Wxx family was designed for embedded systems needing autonomous, battery-backed timekeeping with integrated system supervision - combining RTCC, EEPROM, watchdog, and event detection in a single SPI-accessible IC.

FAQ

What is the backup voltage range supported by the MCP795W20-I/ST?

The MCP795W20-I/ST supports a backup supply voltage range of 1.3V to 3.6V on the VBAT pin. This allows reliable operation from common lithium coin cells (e.g., CR2032, nominal 3.0V) or supercapacitors discharging down to 1.3V. The device automatically switches to VBAT when VCC falls below the 1.3–1.7V trip threshold, ensuring uninterrupted timekeeping and SRAM retention.

Does the MCP795W20-I/ST require external load capacitors for its 32.768 kHz crystal?

Yes, the MCP795W20-I/ST requires external load capacitors on X1 and X2 for crystal operation. It is optimized for 6–9 pF crystals, and the recommended load capacitance must be matched using CX1 and CX2 per Equation 5-1 in the datasheet. The on-chip oscillator does not integrate load caps; omitting them will result in frequency inaccuracy or startup failure.

How does the power-fail timestamp function work in the MCP795W20-I/ST?

The MCP795W20-I/ST automatically logs the exact time of VCC loss (power-down timestamp) and VCC restoration (power-up timestamp) into dedicated registers (0x18–0x1B and 0x1C–0x1F). These timestamps are captured without host intervention and remain accessible via SPI after recovery - enabling forensic analysis of power events in industrial or medical systems where uptime accountability is critical.

Can the MCP795W20-I/ST operate with an external 32.768 kHz clock instead of a crystal?

Yes, the MCP795W20-I/ST supports external clock input on the X1 pin. To enable this mode, the EXTOSC bit in the CONTROL register must be set. When configured for external clock, the X2 pin must be left floating. This bypasses the internal oscillator circuit and allows use of a buffered clock source, improving immunity to board-level noise or vibration affecting crystal stability.

What is the endurance rating of the EEPROM in the MCP795W20-I/ST?

The 2 Kbit EEPROM in the MCP795W20-I/ST is rated for 1 million erase/write cycles under typical conditions (VCC = 3.6V, 25°C). Page writes support up to 8 bytes per operation, and software write-protection prevents unintended modifications. The protected 128-bit EEPROM area uses a separate unlock sequence and shares the same endurance specification.

MCP795W20-I/ST Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 14-TSSOP (0.173", 4.40mm Width)

Packaging:: Tube

Product Status:: Active

Programmable:: Not Verified

Type:: Clock/Calendar

Features:: Alarm, EEPROM, Leap Year, Square Wave Output, SRAM, Watchdog Timer

Memory Size:: 64B

Time Format:: HH:MM:SS:hh (12/24 hr)

Date Format:: YY-MM-DD-dd

Interface:: SPI

Voltage - Supply:: 1.8V ~ 3.6V

Voltage - Supply, Battery:: 1.3V ~ 3.6V

Current - Timekeeping (Max):: 1µA @ 1.8V ~ 5.5V

Operating Temperature:: -40°C ~ 85°C

Mounting Type:: Surface Mount

Grade:: -

Qualification:: -

Supplier Device Package:: 14-TSSOP

MCP795W20-I/ST FAQ

1.How can I place an order for MCP795W20-I/ST through Aetrix?

Please submit a Request for Quotation (RFQ) for MCP795W20-I/ST on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for MCP795W20-I/ST reliable?

The price and inventory of MCP795W20-I/ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MCP795W20-I/ST is usually 5 days.

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MCP795W20-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MCP795W20-I/ST order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for MCP795W20-I/ST?

For technical support, including MCP795W20-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MCP795W20-I/ST requirements.

6.How does Aetrix verify that MCP795W20-I/ST is sourced from the original manufacturer or authorized distributors?

All MCP795W20-I/ST products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MCP795W20-I/ST meets industry standards.

7.What is the process for return or replacement of MCP795W20-I/ST?

All MCP795W20-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with MCP795W20-I/ST, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The MCP795W20-I/ST part is unused and in its original packaging.

Return procedure for MCP795W20-I/ST:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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