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

Microchip Technology MCP795B12-I/ST

Name: MCP795B12-I/ST
Brand: Microchip Technology
SKU: MCP795B12-I/ST
Price: 2.40 USD
Availability: InStock
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Part No.:: MCP795B12-I/ST

Manufacturer:: Microchip Technology

Category:: Real Time Clocks

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

Datasheet:: MCP795B12-I/ST.pdf

Description:: IC RTC CLK/CALENDAR SPI 14TSSOP

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Product details

Overview

MCP795B12-I/ST from Microchip Technology is a SPI real-time clock/calendar (RTCC) IC with integrated 1 Kbit EEPROM, 64-byte battery-backed SRAM, and EUI-64™ unique ID. It delivers accurate timekeeping (hours/minutes/seconds/hundredths/day/month/year/leap year), supports 32 kHz boot-up clock at power-up, operates from 1.8V–5.5V VCC and 1.3V–5.5V VBAT, and enables power-fail time-stamping for industrial metering systems.

For engineers reviewing the MCP795B12-I/ST datasheet, MCP795B12-I/ST pinout, MCP795B12-I/ST application, or MCP795B12-I/ST equivalent, key selection criteria include its 32 kHz boot-up capability, <700 nA VBAT timekeeping current, dual programmable alarms with IRQ/WDO outputs, on-chip digital trimming (±255 ppm in 1 ppm steps), and SPI interface up to 10 MHz.

Technical Context

The MCP795B12-I/ST implements a crystal-based RTCC core with automatic oscillator start and hardware-assisted leap-year correction. Its internal architecture integrates separate time/date registers (0x00–0x07), dual alarm engines (Alarm 0 with seconds resolution, Alarm 1 with hundredths-of-second resolution), and dedicated event-detect circuits - EVHS (pulse-counting: 1st/4th/16th/32nd edge) and EVLS (debounced: 31 ms / 500 ms).

Power management includes autonomous VCC-to-VBAT switchover at 1.3–1.7 V trip point, VBATEN-controlled backup supply enablement, and power-down/power-up time-stamp logging (registers 0x18–0x1F). The device uses BCD-encoded time registers and supports both 12-hour (with AM/PM) and 24-hour formats via software-configurable control bits.

Key Specifications

Parameter	Value and Actual Design Meaning
VCC Range	1.8V to 5.5V - Enables direct interface with 1.8V, 3.3V, and 5V microcontrollers without level-shifting.
VBAT Timekeeping Current	<700 nA @ 1.8V - Ensures multi-year battery life in backup mode using standard coin cells.
SPI Clock Speed	Up to 10 MHz - Supports fast register access and EEPROM writes, reducing host MCU overhead.
Crystal Frequency	32.768 kHz - Requires external tuning-fork crystal and load capacitors; enables precise RTC timing.
Calibration Range	±255 ppm in 1 ppm steps - Allows fine-grained compensation for crystal aging and temperature drift.
EEPROM Endurance	1,000,000 erase/write cycles - Suitable for frequent logging or configuration updates in field-deployed devices.
Operating Temperature	-40°C to +85°C - Qualified for industrial environments including smart meters and building automation.

Pinout & Package

Package: 14-Lead SOIC (Small Outline Integrated Circuit), RoHS-compliant, surface-mount.

Pin/Terminal	Circuit Role	Design Meaning
VSS	Ground reference	Common return path for all analog/digital circuitry; must be low-impedance connection to system ground plane.
X1	Clock input	Connects to one terminal of 32.768 kHz crystal; internal oscillator input; accepts external CMOS clock if X2 is NC.
X2	Clock output	Connects to other crystal terminal; internal oscillator output; leave unconnected when using external clock on X1.
VBAT	Backup supply	Provides continuous power to RTC and SRAM during main supply failure; supports 1.3V–5.5V batteries or supercaps.
VCC	Main supply	Primary power source; powers full functionality including SPI, EEPROM, alarms, and event detection.
SI	SPI data input	Receives instruction, address, and data bits on rising SCK edge; MSB-first protocol.
WDO	Watchdog output	Open-drain N-channel output requiring external pull-up; pulses low on watchdog timeout (user-configurable duration).
SCK	SPI clock	Synchronizes serial communication; data latched on rising edge (SI), updated on falling edge (SO).
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.
CS	Chip select	Active-low enable; deselecting places device in standby (<1 µA ICCS); initiates internal write cycle on low-to-high transition after write sequence.
IRQ	Interrupt output	Shared open-drain output for alarms and event detects; requires external pull-up; remains low until interrupt flag is cleared in software.
EVHS	High-speed event input	Detects rising/falling edges; counts 1st/4th/16th/32nd pulse before asserting IRQ; operates from VCC or VBAT.
EVLS	Low-speed event input	Debounced input with 31 ms or 500 ms filter; suitable for mechanical switch inputs; operates from VCC or VBAT.
SO	SPI data output	Tri-states when CS is high; shifts out data on falling SCK edge; supports bus sharing with multiple SPI slaves.

Key Features

Feature	Design Value
32 kHz Boot-up Clock	Guarantees immediate timebase availability at power-on without waiting for crystal stabilization - critical for fast-boot systems.
Dual Programmable Alarms	Alarm 0 (seconds resolution) and Alarm 1 (hundredths-of-second resolution) support precise scheduling and wake-up events.
Power-Fail Time-Stamping	Automatically logs timestamp when VCC fails and again when restored - enables accurate outage duration tracking in utility meters.
EUI-64™ Unique ID	128-bit factory-programmed MAC address stored in protected EEPROM area - simplifies device identification and network provisioning.
On-Chip Digital Trimming	Software-adjustable ±255 ppm calibration in 1 ppm increments - eliminates need for external trim caps or manual calibration.

Applications

Smart Energy Metering	Industrial PLC Timing
Use Scenario: Utility-grade electricity meter requiring tamper-resistant timekeeping, outage logging, and secure device identity for firmware updates. IC Role / Device Role / Timing Role: Primary RTCC providing calendar-corrected time, power-fail timestamps, and EUI-64™ for secure OTA authentication. Use Value: <700 nA VBAT current extends CR2032 battery life beyond 10 years; 32 kHz boot-up ensures immediate time validity after cold start.	Use Scenario: Programmable logic controller needing deterministic alarm triggers, event counting, and watchdog supervision for safety-critical I/O modules. IC Role / Device Role / Timing Role: Standalone timing co-processor handling real-time scheduling, pulse counting (EVHS), and independent watchdog reset generation (WDO). Use Value: Dual alarms with hundredths-of-second resolution enable sub-second process synchronization; EVHS pulse-counting replaces external counter ICs.
Building Automation Hub	Medical Data Logger
Use Scenario: HVAC controller requiring accurate time-of-day scheduling, battery-backed memory for configuration retention, and low-power operation during mains loss. IC Role / Device Role / Timing Role: Timekeeping and nonvolatile storage subsystem managing schedule execution, SRAM-retained settings, and EEPROM-based log history. Use Value: 64-byte battery-backed SRAM preserves runtime parameters across power cycles; 1 Kbit EEPROM stores firmware version and calibration data.	Use Scenario: Portable patient monitor logging physiological readings with precise timestamps, requiring long-term battery operation and regulatory-compliant traceability. IC Role / Device Role / Timing Role: Certified time source generating ISO 8601-compliant timestamps, storing EUI-64™ for device serialization, and enabling audit-ready time-stamped logs. Use Value: Power-fail timestamping meets IEC 62304 requirements for time continuity; EUI-64™ satisfies FDA UDI traceability mandates.

Smart Energy Metering

Industrial PLC Timing

Use Scenario: Utility-grade electricity meter requiring tamper-resistant timekeeping, outage logging, and secure device identity for firmware updates.

IC Role / Device Role / Timing Role: Primary RTCC providing calendar-corrected time, power-fail timestamps, and EUI-64™ for secure OTA authentication.

Use Value: <700 nA VBAT current extends CR2032 battery life beyond 10 years; 32 kHz boot-up ensures immediate time validity after cold start.

Use Scenario: Programmable logic controller needing deterministic alarm triggers, event counting, and watchdog supervision for safety-critical I/O modules.

IC Role / Device Role / Timing Role: Standalone timing co-processor handling real-time scheduling, pulse counting (EVHS), and independent watchdog reset generation (WDO).

Use Value: Dual alarms with hundredths-of-second resolution enable sub-second process synchronization; EVHS pulse-counting replaces external counter ICs.

Building Automation Hub

Medical Data Logger

Use Scenario: HVAC controller requiring accurate time-of-day scheduling, battery-backed memory for configuration retention, and low-power operation during mains loss.

IC Role / Device Role / Timing Role: Timekeeping and nonvolatile storage subsystem managing schedule execution, SRAM-retained settings, and EEPROM-based log history.

Use Value: 64-byte battery-backed SRAM preserves runtime parameters across power cycles; 1 Kbit EEPROM stores firmware version and calibration data.

Use Scenario: Portable patient monitor logging physiological readings with precise timestamps, requiring long-term battery operation and regulatory-compliant traceability.

IC Role / Device Role / Timing Role: Certified time source generating ISO 8601-compliant timestamps, storing EUI-64™ for device serialization, and enabling audit-ready time-stamped logs.

Use Value: Power-fail timestamping meets IEC 62304 requirements for time continuity; EUI-64™ satisfies FDA UDI traceability mandates.

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
MCP795W12-I/ST	Lacks 32 kHz boot-up clock; identical EEPROM, SRAM, EUI-64™, and alarm features.	Not suitable where immediate post-power-up timebase is required; acceptable for systems with longer boot sequences.	Select MCP795W12-I/ST only if boot-clock functionality is unnecessary and cost optimization is prioritized.
DS3231M+	Integrated TCXO (±2 ppm accuracy); higher VCC min (2.3V); no EVHS/EVLS inputs; no EUI-64™; I²C interface only.	Better accuracy for precision instrumentation; lacks event detection and SPI flexibility; requires different MCU interface.	Choose DS3231M+ when absolute time accuracy outweighs feature set and interface compatibility.

Compared with MCP795W12-I/ST, the MCP795B12-I/ST adds guaranteed 32 kHz boot-up timing without external components, while DS3231M+ trades SPI/EVHS/EUI-64™ for superior oscillator stability and I²C simplicity - making MCP795B12-I/ST optimal for feature-rich, SPI-based industrial designs requiring fast timebase availability.

Availability

MCP795B12-I/ST is available at Aetrix Electronics and suitable for smart energy metering, industrial PLC timing, building automation hubs, and medical data loggers requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MCP795B12-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 microcontroller, mixed-signal, analog, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with high-reliability semiconductor products.

The MCP795XXX product line was designed specifically for embedded systems requiring robust, low-power real-time clock/calendar functionality with integrated nonvolatile memory, battery switchover, and enhanced system supervision features like watchdog and event detection.

FAQ

What is the primary function of the MCP795B12-I/ST?

The MCP795B12-I/ST is a SPI real-time clock/calendar IC that maintains accurate time and date (including leap-year correction), provides 64-byte battery-backed SRAM and 1 Kbit EEPROM, supports dual programmable alarms, and delivers a 32 kHz boot-up clock at power-on. Its design centers on reliable, low-power timekeeping for industrial and metering applications where data integrity and power-fail resilience are essential - and the MCP795B12-I/ST fulfills this with hardware-enforced VCC-to-VBAT switchover and power-fail timestamping.

Does the MCP795B12-I/ST require an external crystal?

Yes, the MCP795B12-I/ST requires an external 32.768 kHz tuning-fork crystal connected between X1 and X2 pins, along with appropriate load capacitors. It does not contain an integrated oscillator; however, it supports external CMOS clock input on X1 (with X2 left unconnected) as an alternative to the crystal. The MCP795B12-I/ST uses this crystal to drive both the RTCC core and the CLKOUT/BOOT pin, which asserts 32 kHz immediately at power-up - a feature confirmed for the MCP795BXX family in the device selection table.

How does the MCP795B12-I/ST handle power failure and battery switchover?

The MCP795B12-I/ST automatically switches from VCC to VBAT when VCC drops below 1.3–1.7 V (typical 1.5 V), maintaining timekeeping and SRAM contents. It logs timestamps at both power-fail and power-restore events in dedicated registers (0x18–0x1F). The VBATEN bit (register 0x04:3) must be set to enable backup supply connection. This behavior is intrinsic to the MCP795B12-I/ST's power sense circuit and is validated across the MCP795BXX series - ensuring uninterrupted operation and outage diagnostics without host intervention.

What memory resources are integrated into the MCP795B12-I/ST?

The MCP795B12-I/ST integrates three memory types: (1) 64-byte battery-backed SRAM (addresses 0x20–0x5F), retained during VCC loss; (2) 1 Kbit (128-byte) EEPROM with software write-protection and 1M endurance; and (3) a 128-bit protected EEPROM area preprogrammed with EUI-64™ unique ID. All are accessible via SPI, and the MCP795B12-I/ST's memory map explicitly allocates these blocks - distinguishing RTCC registers (0x00–0x1F), SRAM (0x20–0x5F), and EEPROM (0x00–0x7F) with no overlap.

Can the MCP795B12-I/ST generate clock outputs other than 32 kHz?

Yes, the MCP795B12-I/ST's CLKOUT/BOOT pin supports four selectable frequencies: 1 Hz, 4.096 kHz, 8.192 kHz, and 32.768 kHz - configured via RS2:RS0 bits (register 0x08:2–0). While it asserts 32 kHz at power-up (a defining trait of MCP795BXX variants), the output can be reconfigured in runtime to any of the four options. The SQWE bit (0x08:6) enables this divided output, and calibration adjustments apply to all modes - confirming flexible timing signal generation beyond boot-up in the MCP795B12-I/ST.

MCP795B12-I/ST Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

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

MCP795B12-I/ST FAQ

1.How can I place an order for MCP795B12-I/ST through Aetrix?

Please submit a Request for Quotation (RFQ) for MCP795B12-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 MCP795B12-I/ST reliable?

The price and inventory of MCP795B12-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 MCP795B12-I/ST is usually 5 days.

3.What payment methods are accepted for MCP795B12-I/ST?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MCP795B12-I/ST transactions.

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4.How is shipping managed for MCP795B12-I/ST?

MCP795B12-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MCP795B12-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 MCP795B12-I/ST?

For technical support, including MCP795B12-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MCP795B12-I/ST requirements.

6.How does Aetrix verify that MCP795B12-I/ST is sourced from the original manufacturer or authorized distributors?

All MCP795B12-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 MCP795B12-I/ST meets industry standards.

7.What is the process for return or replacement of MCP795B12-I/ST?

All MCP795B12-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with MCP795B12-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 MCP795B12-I/ST part is unused and in its original packaging.

Return procedure for MCP795B12-I/ST:

1.Submit a request within 90 days.

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

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