Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

Microchip Technology MCP795B21-I/SL

Name: MCP795B21-I/SL
Brand: Microchip Technology
SKU: MCP795B21-I/SL
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: MCP795B21-I/SL

Manufacturer:: Microchip Technology

Category:: Real Time Clocks

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

Datasheet:: MCP795B21-I/SL.pdf

Description:: IC RTC CLK/CALENDAR SPI 14SOIC

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:4,668

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

MCP795B21-I/SL from Microchip Technology is a SPI real-time clock/calendar (RTCC) IC with integrated 64-byte battery-backed SRAM, 2 Kbit EEPROM, EUI-48™ unique ID, and 32 kHz boot-up clock capability. It operates from 1.8V–5.5V VCC and 1.3V–5.5V VBAT, delivers <700 nA timekeeping current at 1.8V, supports dual programmable alarms, digital trimming (±255 ppm), and power-fail time-stamping - used in industrial metering and backup-power-critical embedded systems.

For engineers reviewing the MCP795B21-I/SL datasheet, MCP795B21-I/SL pinout, MCP795B21-I/SL application, or MCP795B21-I/SL equivalent, key selection criteria include VBAT switchover behavior, 32 kHz boot-clock timing on CLKOUT/BOOT, EUI-48™ provisioning, SRAM retention under brownout, and SPI interface compatibility with 10 MHz clock support.

Technical Context

The MCP795B21-I/SL implements a digitally trimmed 32.768 kHz crystal oscillator with automatic VCC-to-VBAT switchover (trip point 1.3–1.7 V), enabling continuous timekeeping during main power loss. Its RTCC registers (0x00–0x1F) maintain BCD-encoded time/date with leap-year correction, 24-/12-hour format, and hundredth-of-second resolution via Alarm 1.

It integrates dual event detect inputs (EVHS with pulse-counting for 1st/4th/16th/32nd edge; EVLS with 31 ms/500 ms debounce), a dedicated watchdog output (WDO), and shared IRQ for alarms/events - all functional from VCC or VBAT. The SPI interface supports full-duplex communication up to 10 MHz with CS-controlled standby and high-impedance SO during deselect.

Key Specifications

Parameter	Value and Actual Design Meaning
VCC Range	1.8V to 5.5V - supports direct connection to common microcontroller I/O rails without level-shifting.
VBAT Range	1.3V to 5.5V - enables use of single-cell Li-ion or coin cells for long-term backup without external regulators.
Timekeeping Current	<700 nA at 1.8V - extends battery life beyond 10 years in typical coin-cell backup configurations.
SPI Clock Speed	Up to 10 MHz - allows sub-millisecond alarm latency and fast EEPROM/SRAM access in time-critical systems.
Digital Trimming	±255 ppm in 1 ppm steps - enables field calibration to compensate for crystal aging, temperature drift, or load capacitance mismatch.
Unique ID	EUI-48™ preprogrammed - provides globally unique MAC address for networked device identification and secure boot binding.
Boot-up Clock	32 kHz on CLKOUT/BOOT at power-up - supplies immediate timing reference to host MCU before firmware initialization completes.

Pinout & Package

Package: 14-Lead SOIC (Small Outline Integrated Circuit), RoHS-compliant, 1.27 mm pitch, body size 8.65 × 3.90 × 1.75 mm.

Pin/Terminal	Circuit Role	Design Meaning
1 (X1)	Crytal oscillator input	Drives internal oscillator with external 32.768 kHz tuning fork crystal; also accepts CMOS clock input when X2 is NC.
2 (X2)	Crytal oscillator output	Output node of internal oscillator circuit; must be left unconnected if using external CMOS clock on X1.
3 (VBAT)	Backup supply input	Provides power to RTC registers and SRAM during VCC failure; activates automatic switchover at 1.3–1.7 V threshold.
4 (WDO)	Watchdog timer output	Open-drain N-channel output requiring external pull-up; pulses low on WDT timeout with user-selectable duration (0.1–2.5 s).
5 (IRQ)	Interrupt/event output	Shared open-drain output for alarms, EVHS/EVLS events, or WDT overflow; requires external pull-up to VCC or VBAT.
6 (CS)	Chip select input	Active-low SPI enable; forces device into standby when high, places SO in high-impedance state for bus sharing.
7 (VSS)	Ground reference	Primary digital ground return path; must be connected to system GND with low-inductance trace for noise immunity.
8 (SCK)	SPI clock input	Synchronizes data transfer; rising edge latches SI, falling edge updates SO; supports up to 10 MHz operation.
9 (SI)	SPI data input	Receives instruction, address, and data bytes MSb-first; sampled on SCK rising edge per SPI Mode 0/3.
10 (SO)	SPI data output	Transmits register/EEPROM/SRAM data MSb-first; driven only when CS is low and data is valid.
11 (EVLS)	Low-speed event input	Debounced digital input with programmable 31 ms or 500 ms filter; supports mechanical switch interfaces without external RC.
12 (EVHS)	High-speed event input	Edge-triggered input supporting pulse counting for 1st/4th/16th/32nd event detection; operates from VCC or VBAT.
13 (CLKOUT/BOOT)	Configurable clock output	Push-pull output delivering 1 Hz / 4.096 kHz / 8.192 kHz / 32.768 kHz; asserts 32 kHz at power-up for MCP795BXX variants.
14 (VCC)	Main supply input	Primary power rail; powers all logic, SPI interface, and EEPROM writes; regulates internal LDO for oscillator stability.

Key Features

Feature	Design Value
32 kHz Boot-up Clock	Guarantees immediate timing reference on power-up via CLKOUT/BOOT pin - eliminates startup delay in host MCU clock initialization.
Power-Fail Time-Stamping	Automatically logs timestamp at VCC dropout and restoration (registers 0x18–0x1F), enabling accurate outage duration measurement in energy meters.
Dual Programmable Alarms	Alarm 0 (second-resolution) and Alarm 1 (hundredth-second resolution) support independent IRQ/WDO triggering for multi-level scheduling.
Battery-Backed SRAM + EEPROM	64-byte SRAM retains volatile runtime data; 2 Kbit EEPROM stores configuration with 1M write cycles and software block protection (¼/½/full).
EUI-48™ Unique ID	Factory-programmed 48-bit MAC address in protected EEPROM space - enables secure device identity binding without user programming effort.
Digital Trimming Calibration	8-bit CALIBRATION register (±255 ppm, 1 ppm step) compensates crystal frequency error without external components or firmware recalibration loops.

Applications

Smart Energy Metering	Industrial PLC Real-Time Logging
Use Scenario: Recording kWh consumption with precise time-stamped intervals during grid outages and recovery. IC Role / Device Role / Timing Role: Primary timekeeping engine with VBAT switchover, power-fail timestamp logging, and alarm-driven data capture triggers. Use Value: Maintains sub-second time accuracy across brownouts using <700 nA VBAT current and logs exact outage duration via dedicated time-stamp registers.	Use Scenario: Capturing sensor readings and control events with synchronized timestamps across distributed I/O modules. IC Role / Device Role / Timing Role: Centralized RTCC providing deterministic time base for event sequencing, alarm-based diagnostics, and firmware update scheduling. Use Value: Enables coordinated time-stamping across multiple nodes using EUI-48™ identity and 10 MHz SPI for low-latency register access.
Medical Infusion Pump Control	Networked Building Automation
Use Scenario: Ensuring dose delivery timing integrity during AC power loss or battery transition in Class II medical devices. IC Role / Device Role / Timing Role: Fail-safe timekeeper with battery-backed SRAM storing therapy parameters and watchdog supervision of pump motor controller. Use Value: Guarantees uninterrupted timekeeping and alarm generation (<1 µA VCC standby) while supporting regulatory traceability via power-fail timestamps.	Use Scenario: Synchronizing HVAC schedules, lighting control, and occupancy sensing across IP-connected edge controllers. IC Role / Device Role / Timing Role: Embedded time source for local decision-making, NTP client fallback, and secure device onboarding using EUI-48™ identity. Use Value: Delivers IEEE 802.3-compliant MAC addressing and robust event detection (EVHS/EVLS) for switch and sensor integration without MCU overhead.

Smart Energy Metering

Industrial PLC Real-Time Logging

Use Scenario: Recording kWh consumption with precise time-stamped intervals during grid outages and recovery.

IC Role / Device Role / Timing Role: Primary timekeeping engine with VBAT switchover, power-fail timestamp logging, and alarm-driven data capture triggers.

Use Value: Maintains sub-second time accuracy across brownouts using <700 nA VBAT current and logs exact outage duration via dedicated time-stamp registers.

Use Scenario: Capturing sensor readings and control events with synchronized timestamps across distributed I/O modules.

IC Role / Device Role / Timing Role: Centralized RTCC providing deterministic time base for event sequencing, alarm-based diagnostics, and firmware update scheduling.

Use Value: Enables coordinated time-stamping across multiple nodes using EUI-48™ identity and 10 MHz SPI for low-latency register access.

Medical Infusion Pump Control

Networked Building Automation

Use Scenario: Ensuring dose delivery timing integrity during AC power loss or battery transition in Class II medical devices.

IC Role / Device Role / Timing Role: Fail-safe timekeeper with battery-backed SRAM storing therapy parameters and watchdog supervision of pump motor controller.

Use Value: Guarantees uninterrupted timekeeping and alarm generation (<1 µA VCC standby) while supporting regulatory traceability via power-fail timestamps.

Use Scenario: Synchronizing HVAC schedules, lighting control, and occupancy sensing across IP-connected edge controllers.

IC Role / Device Role / Timing Role: Embedded time source for local decision-making, NTP client fallback, and secure device onboarding using EUI-48™ identity.

Use Value: Delivers IEEE 802.3-compliant MAC addressing and robust event detection (EVHS/EVLS) for switch and sensor integration without MCU overhead.

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
MCP795W21-I/SL	Lacks 32 kHz boot-up clock on CLKOUT/BOOT; identical EEPROM, SRAM, EUI-48™, and trimming capability.	Not suitable where immediate post-power-up timing reference is required; acceptable for systems with controlled boot sequence.	Select MCP795W21-I/SL only if boot-clock functionality is unnecessary and cost optimization is prioritized.
DS3231SN#T&R	Includes internal TCXO (±2 ppm accuracy), higher VBAT current (~3 µA), no EUI-48™, different pinout (8-pin SO), I²C-only interface.	Better absolute accuracy over temperature but lacks SPI, event inputs, and programmable alarms; requires I²C host.	Choose DS3231SN#T&R when ultra-high accuracy outweighs need for SPI, event detection, or EUI-48™ identity.

Compared with MCP795W21-I/SL, the MCP795B21-I/SL adds critical boot-time clocking without sacrificing memory or ID features; versus DS3231SN#T&R, it trades TCXO precision for SPI flexibility, dual event inputs, and deterministic alarm resolution - making it optimal for resource-constrained, event-driven industrial designs.

Availability

MCP795B21-I/SL is available at Aetrix Electronics and suitable for smart metering, industrial PLC logging, medical infusion pumps, and networked building automation requiring stable component supply, long-term lifecycle support, and guaranteed EUI-48™ provisioning.

Supply support for MCP795B21-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 devices, and timing solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The MCP795XXX product line delivers highly integrated SPI real-time clock/calendars with battery switchover, nonvolatile memory, and enhanced system monitoring - designed specifically for industrial, medical, and energy infrastructure applications demanding reliability and long-term support.

FAQ

What is the function of the CLKOUT/BOOT pin on the MCP795B21-I/SL?

The CLKOUT/BOOT pin on the MCP795B21-I/SL is a push-pull output that delivers configurable clock frequencies (1 Hz, 4.096 kHz, 8.192 kHz, or 32.768 kHz) during normal operation. Crucially, for MCP795BXX variants like the MCP795B21-I/SL, it asserts a 32 kHz square wave immediately at power-up - providing an instant timing reference to the host MCU before firmware initialization completes. This boot-clock behavior distinguishes it from the MCP795WXX series.

Does the MCP795B21-I/SL support both 12-hour and 24-hour time formats?

Yes, the MCP795B21-I/SL supports both time formats. Bit 6 (12/24) in the HOUR register (0x03) controls this setting: clearing it selects 24-hour mode, while setting it enables 12-hour mode with AM/PM indication encoded in bits 5 and 4. The device automatically handles date rollover, month-length variation, and leap-year correction regardless of format selection - all managed in hardware without host MCU intervention.

How does the power-fail time-stamping feature work in the MCP795B21-I/SL?

The MCP795B21-I/SL automatically logs timestamps when VCC fails (power-down) and when VCC is restored (power-up) using dedicated registers 0x18–0x1F. This occurs transparently via the internal power-sense circuit, requiring no host software action. The VBATEN bit (0x04:3) must be set to enable VBAT backup, and the VBAT pin must be connected to a valid backup source. Timestamps are stored in BCD format and remain accessible after recovery for outage duration analysis.

What is the purpose of the EVHS and EVLS pins on the MCP795B21-I/SL?

The EVHS (High-Speed Event Detect) and EVLS (Low-Speed Event Detect) pins on the MCP795B21-I/SL provide dedicated hardware event counting and debouncing. EVHS supports edge-triggered pulse counting for the 1st, 4th, 16th, or 32nd event before asserting IRQ; EVLS offers programmable 31 ms or 500 ms digital debounce for noisy mechanical switches. Both operate from VCC or VBAT, enabling robust external event handling without consuming host MCU GPIO or timer resources.

Is the EUI-48™ unique ID in the MCP795B21-I/SL factory-programmed or user-programmable?

The EUI-48™ unique ID in the MCP795B21-I/SL is factory-programmed and delivered preconfigured - not user-programmable in standard configuration. It resides in a protected 128-bit EEPROM area and is accessible via the IDREAD instruction (0b00110011). While an unlock sequence exists for custom programming, Microchip ships the MCP795B21-I/SL with EUI-48™ preloaded, ensuring globally unique MAC address compliance out-of-box for networked device identity and secure boot binding.

MCP795B21-I/SL Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

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

Packaging:: Tube

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

MCP795B21-I/SL FAQ

1.How can I place an order for MCP795B21-I/SL through Aetrix?

Please submit a Request for Quotation (RFQ) for MCP795B21-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 MCP795B21-I/SL reliable?

The price and inventory of MCP795B21-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 MCP795B21-I/SL is usually 5 days.

3.What payment methods are accepted for MCP795B21-I/SL?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MCP795B21-I/SL transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MCP795B21-I/SL?

MCP795B21-I/SL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MCP795B21-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 MCP795B21-I/SL?

For technical support, including MCP795B21-I/SL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MCP795B21-I/SL requirements.

6.How does Aetrix verify that MCP795B21-I/SL is sourced from the original manufacturer or authorized distributors?

All MCP795B21-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 MCP795B21-I/SL meets industry standards.

7.What is the process for return or replacement of MCP795B21-I/SL?

All MCP795B21-I/SL units undergo pre-shipment inspection (PSI). If there is an issue with MCP795B21-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 MCP795B21-I/SL part is unused and in its original packaging.

Return procedure for MCP795B21-I/SL:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…