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

Microchip Technology MCP795B20T-I/SL

Name: MCP795B20T-I/SL
Brand: Microchip Technology
SKU: MCP795B20T-I/SL
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MCP795B20T-I/SL

Manufacturer:: Microchip Technology

Category:: Real Time Clocks

Package:: 14-SOIC (0.154", 3.90mm Width)

Datasheet:: MCP795B20T-I/SL.pdf

Description:: IC RTC CLK/CALENDAR SPI 14SOIC

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Product details

Overview

MCP795B20T-I/SL from Microchip Technology is a SPI real-time clock/calendar (RTCC) IC with integrated 64-byte battery-backed SRAM, 2 Kbit EEPROM, and dual programmable alarms. It features 32 kHz boot-up clock at power-up, digital trimming (±255 ppm), power-fail time-stamping, and operates from 1.8V to 5.5V VCC or 1.3V to 5.5V VBAT - used in industrial metering, backup power logging, and embedded systems requiring accurate timekeeping during main power loss.

For engineers reviewing the MCP795B20T-I/SL datasheet, MCP795B20T-I/SL pinout, MCP795B20T-I/SL application, or MCP795B20T-I/SL equivalent, key selection criteria include VBAT switchover behavior, 32 kHz boot-clock capability, alarm resolution (hundredths of seconds), EEPROM endurance (1M cycles), and SPI timing compliance at 10 MHz.

Technical Context

The MCP795B20T-I/SL implements a crystal-based RTCC with on-chip oscillator driving a 32.768 kHz tuning fork crystal, supporting automatic VCC-to-VBAT switchover at 1.3–1.7 V threshold. Its 32 kHz boot-up clock on CLKOUT/BOOT enables immediate timebase availability at power-on without external initialization.

It integrates dual event detect inputs (EVHS/EVLS) with programmable pulse counting (1st/4th/16th/32nd) and debounce filtering (31 ms / 500 ms), plus a dedicated watchdog output (WDO) with user-selectable pulse duration - all functional under VBAT for fail-safe operation.

Key Specifications

Parameter	Value and Actual Design Meaning
VCC Range	1.8V to 5.5V - supports direct interface with 3.3V and 5V microcontrollers without level shifting.
VBAT Range	1.3V to 5.5V - enables use with single-cell Li-ion or coin cells (e.g., CR2032) for extended backup.
Timekeeping Current (VBAT)	<700 nA @ 1.8V - ensures >10-year battery life with typical 220 mAh coin cell.
SPI Clock Speed	Up to 10 MHz - allows sub-millisecond register access and fast EEPROM writes (≤5 ms internal cycle).
Alarm Resolution	Hundredths of seconds (Alarm 1) - enables precise scheduling for data logging or wake-up triggers.
Digital Trimming Range	±255 ppm in 1 ppm steps - permits field calibration to compensate for crystal aging or temperature drift.
EEPROM Endurance	1,000,000 erase/write cycles - suitable for frequent timestamp or configuration updates in industrial logging.

Pinout & Package

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

Pin/Terminal	Circuit Role	Design Meaning
VSS	Ground reference	Common return path for all analog/digital circuits; must be low-impedance connection to minimize noise coupling into RTC accuracy.
X1	Clock input to oscillator	Accepts 32.768 kHz crystal or external CMOS clock; internal oscillator biasing enables direct crystal drive without external components.
X2	Oscillator output	Crystal output node; left unconnected when using external clock source on X1.
VBAT	Backup power supply	Provides continuous power to RTC registers and SRAM during VCC failure; activates automatically at VCC ≤1.7 V.
VCC	Main power supply	Primary operating voltage; powers SPI interface, EEPROM write, and full functionality including alarms and event detects.
SI	SPI serial data input	Latches instruction/address/data on rising SCK edge; supports standard SPI mode 0 (CPOL=0, CPHA=0).
WDO	Watchdog open-drain output	Pulls low on timeout; requires external pull-up to VCC/VBAT; sink current rated to 10 mA for direct MCU reset assertion.
SCK	SPI clock input	Synchronizes all SPI transfers; max frequency 10 MHz at VCC ≥4.5V, scaling down to 3 MHz at 1.8V.
CLKOUT/BOOT	Configurable clock output	Delivers 32 kHz square wave at power-up (MCP795BXX-specific); configurable for 1 Hz / 4.096 kHz / 8.192 kHz / 32.768 kHz via RS bits.
CS	Chip select input	Active-low enable; forces device into standby when high; SO enters high-impedance state to support multi-slave SPI buses.
IRQ	Open-drain interrupt output	Shared alarm/event output; pulls low on Alarm 0/1 trigger or EVHS/EVLS detection; cleared only by software flag reset.
EVHS	High-speed event input	Edge-triggered (rising/falling); counts pulses up to 32nd occurrence before asserting IRQ; operates from VCC or VBAT.
EVLS	Low-speed event input	Debounced mechanical switch input; 31 ms or 500 ms filter selectable; retains function during VCC dropout.
SO	SPI serial data output	Drives data on falling SCK edge; high-impedance when CS is high to prevent bus contention.

Key Features

Feature	Design Value
32 kHz Boot-up Clock	Immediate 32.768 kHz clock on CLKOUT/BOOT at power-on - eliminates startup delay for time-critical applications like black-box logging.
Power-Fail Time-Stamp	Automatically logs exact time of VCC failure and restoration in dedicated registers (0x18–0x1F) - enables accurate outage duration analysis without host intervention.
Dual Programmable Alarms	Alarm 0 (seconds resolution) and Alarm 1 (hundredths-of-second resolution) with independent IRQ/WDO routing - supports both coarse scheduling and precision wake-up.
Battery-Backed SRAM + EEPROM	64-byte SRAM retained under VBAT; 2 Kbit EEPROM with ¼/½/full software write-protection - preserves critical runtime data and firmware parameters across power cycles.
On-Chip Digital Trimming	±255 ppm adjustment in 1 ppm increments via CALIBRATION register - enables one-time factory calibration or field recalibration without hardware changes.

Applications

Smart Energy Metering	Industrial Data Logger
Use Scenario: Utility meters recording consumption every 15 minutes with tamper detection and outage reporting. IC Role / Device Role / Timing Role: Primary timekeeping engine with power-fail timestamping, alarm-driven data upload, and EEPROM storage of tariff schedules and event logs. Use Value: Maintains accurate time across mains outages; logs exact start/end of each outage in nonvolatile memory for regulatory compliance reporting.	Use Scenario: Remote environmental sensor nodes logging temperature/humidity every 10 seconds with battery backup. IC Role / Device Role / Timing Role: Low-power RTC coordinating sampling intervals, managing SRAM buffer overflow to EEPROM, and triggering wake-up via EVLS on button press. Use Value: Enables <700 nA VBAT current draw to extend 220 mAh coin cell life beyond 10 years while preserving timestamp integrity.
Medical Device Clock Backup	POS Terminal Transaction Logging
Use Scenario: Portable diagnostic equipment requiring audit-trail timestamps for FDA-regulated usage records. IC Role / Device Role / Timing Role: Tamper-resistant time source with EUI-48™ unique ID preprogrammed for device identification and cryptographic key binding. Use Value: Provides cryptographically verifiable, battery-backed timestamps traceable to device identity - satisfies 21 CFR Part 11 electronic record requirements.	Use Scenario: Point-of-sale terminals capturing transaction timestamps even during AC power interruption. IC Role / Device Role / Timing Role: Real-time clock with dual alarms triggering secure log commits to EEPROM and initiating watchdog resets if host MCU hangs. Use Value: Guarantees transaction sequence integrity and prevents data loss during brownouts via autonomous VBAT-powered logging.

Smart Energy Metering

Industrial Data Logger

Use Scenario: Utility meters recording consumption every 15 minutes with tamper detection and outage reporting.

IC Role / Device Role / Timing Role: Primary timekeeping engine with power-fail timestamping, alarm-driven data upload, and EEPROM storage of tariff schedules and event logs.

Use Value: Maintains accurate time across mains outages; logs exact start/end of each outage in nonvolatile memory for regulatory compliance reporting.

Use Scenario: Remote environmental sensor nodes logging temperature/humidity every 10 seconds with battery backup.

IC Role / Device Role / Timing Role: Low-power RTC coordinating sampling intervals, managing SRAM buffer overflow to EEPROM, and triggering wake-up via EVLS on button press.

Use Value: Enables <700 nA VBAT current draw to extend 220 mAh coin cell life beyond 10 years while preserving timestamp integrity.

Medical Device Clock Backup

POS Terminal Transaction Logging

Use Scenario: Portable diagnostic equipment requiring audit-trail timestamps for FDA-regulated usage records.

IC Role / Device Role / Timing Role: Tamper-resistant time source with EUI-48™ unique ID preprogrammed for device identification and cryptographic key binding.

Use Value: Provides cryptographically verifiable, battery-backed timestamps traceable to device identity - satisfies 21 CFR Part 11 electronic record requirements.

Use Scenario: Point-of-sale terminals capturing transaction timestamps even during AC power interruption.

IC Role / Device Role / Timing Role: Real-time clock with dual alarms triggering secure log commits to EEPROM and initiating watchdog resets if host MCU hangs.

Use Value: Guarantees transaction sequence integrity and prevents data loss during brownouts via autonomous VBAT-powered logging.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MCP795W20T-I/SL	No 32 kHz boot-up clock; identical SRAM, EEPROM, alarms, and trimming.	Cannot provide immediate clock output at power-on; unsuitable where instant timebase is required.	Select MCP795B20T-I/SL when boot-time clock availability is mandatory; choose MCP795W20T-I/SL only if boot-clock is unused and cost optimization is primary.
DS3231SN#T&R	Integrated TCXO (±2 ppm accuracy), higher VCC min (2.3V), no EVHS/EVLS inputs, no boot clock.	Superior accuracy without calibration; lacks event inputs and boot-clock; uses I²C not SPI.	Choose DS3231SN#T&R for highest accuracy in temperature-variable environments; retain MCP795B20T-I/SL for SPI interface, event detection, and boot-clock needs.

Compared with MCP795W20T-I/SL, the MCP795B20T-I/SL adds guaranteed 32 kHz boot-clock functionality essential for deterministic power-on timing, while retaining identical memory, alarm, and calibration capabilities. Against DS3231SN#T&R, it trades absolute accuracy for SPI compatibility, dual event inputs, and boot-clock - making it better suited for resource-constrained, event-driven embedded designs.

Availability

MCP795B20T-I/SL is available at Aetrix Electronics and suitable for smart metering, industrial data logging, medical device timestamping, and POS terminal backup power applications requiring stable component supply and long-term lifecycle support.

Supply support for MCP795B20T-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, serving automotive, industrial, consumer, and communications markets.

The MCP795BXX series is part of Microchip's enhanced RTCC product line, designed specifically for embedded systems needing robust timekeeping with battery switchover, event detection, and programmable alarms - targeting applications where reliability under power disruption is critical.

FAQ

What is the boot-up clock behavior of the MCP795B20T-I/SL?

The MCP795B20T-I/SL asserts a 32 kHz square wave on the CLKOUT/BOOT pin immediately at power-up, derived from the same 32.768 kHz crystal driving the RTC. This feature is exclusive to the MCP795BXX family and is not present in the MCP795WXX variants. The output remains active until reconfigured via the RS bits in Control Register 0x08, enabling deterministic timing for host MCU initialization sequences.

How does the MCP795B20T-I/SL handle power failure and restoration?

The MCP795B20T-I/SL automatically switches from VCC to VBAT when VCC drops below 1.3–1.7 V (typical 1.5 V). During switchover, it logs the exact time of VCC failure into Power-down Time-stamp registers (0x18–0x1F) and records restoration time in Power-Up registers (0x1C–0x1F). Both timestamps are stored in battery-backed memory and remain accessible after recovery - no host intervention is required.

What are the differences between Alarm 0 and Alarm 1 in the MCP795B20T-I/SL?

Alarm 0 (registers 0x0C–0x11) provides second-level resolution and supports basic time-of-day or date matching. Alarm 1 (registers 0x12–0x17) adds hundredths-of-second resolution and enhanced compare logic, enabling sub-second precision for applications like synchronized data capture or high-frequency event scheduling. Both alarms can independently assert IRQ or WDO and are fully programmable via SPI.

Can the MCP795B20T-I/SL operate solely from VBAT without VCC?

Yes - the MCP795B20T-I/SL maintains RTC operation, SRAM retention, and alarm/event detection functions from VBAT alone (1.3V–5.5V), provided VBATEN bit (0x04:3) is set. However, SPI communication, EEPROM writes, and CLKOUT configuration require VCC. Critical functions like timekeeping, power-fail timestamping, and IRQ assertion remain fully operational under VBAT-only conditions.

Does the MCP795B20T-I/SL support external clock input instead of a crystal?

Yes - setting the EXTOSC bit (0x08:3) enables the MCP795B20T-I/SL to accept an external 32.768 kHz CMOS clock signal applied to the X1 pin, bypassing the internal oscillator and crystal. In this mode, X2 must be left unconnected. This configuration reduces BOM count and improves immunity to crystal-related aging or shock sensitivity in high-reliability applications.

MCP795B20T-I/SL Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 14-SOIC (0.154", 3.90mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Programmable:: Not Verified

Type:: Clock/Calendar

Features:: Alarm, EEPROM, Leap Year, Square Wave Output, SRAM, Unique ID, 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 ~ 5.5V

Voltage - Supply, Battery:: 1.3V ~ 5.5V

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

Operating Temperature:: -40°C ~ 85°C

Mounting Type:: Surface Mount

Grade:: -

Qualification:: -

Supplier Device Package:: 14-SOIC

MCP795B20T-I/SL FAQ

1.How can I place an order for MCP795B20T-I/SL through Aetrix?

Please submit a Request for Quotation (RFQ) for MCP795B20T-I/SL 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 MCP795B20T-I/SL reliable?

The price and inventory of MCP795B20T-I/SL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MCP795B20T-I/SL is usually 5 days.

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MCP795B20T-I/SL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MCP795B20T-I/SL 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 MCP795B20T-I/SL?

For technical support, including MCP795B20T-I/SL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MCP795B20T-I/SL requirements.

6.How does Aetrix verify that MCP795B20T-I/SL is sourced from the original manufacturer or authorized distributors?

All MCP795B20T-I/SL 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 MCP795B20T-I/SL meets industry standards.

7.What is the process for return or replacement of MCP795B20T-I/SL?

All MCP795B20T-I/SL units undergo pre-shipment inspection (PSI). If there is an issue with MCP795B20T-I/SL, 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 MCP795B20T-I/SL part is unused and in its original packaging.

Return procedure for MCP795B20T-I/SL:

1.Submit a request within 90 days.

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

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