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

Microchip Technology MCP795B12T-I/ST

Name: MCP795B12T-I/ST
Brand: Microchip Technology
SKU: MCP795B12T-I/ST
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MCP795B12T-I/ST

Manufacturer:: Microchip Technology

Category:: Real Time Clocks

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

Datasheet:: MCP795B12T-I/ST.pdf

Description:: IC RTC CLK/CALENDAR SPI 14TSSOP

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Product details

Overview

MCP795B12T-I/ST from Microchip Technology is a SPI real-time clock/calendar (RTCC) IC with integrated 64-byte battery-backed SRAM, 1 Kbit EEPROM, EUI-64™ unique ID, and 32 kHz boot-up clock on CLKOUT/BOOT pin. It supports digital trimming (±255 ppm in 1 ppm steps), dual programmable alarms, power-fail time-stamping, and operates from 1.8V to 5.5V VCC or 1.3V to 5.5V VBAT. It is used in industrial metering, backup power systems, and embedded controllers requiring precise timekeeping during main power loss.

For engineers reviewing the MCP795B12T-I/ST datasheet, MCP795B12T-I/ST pinout, MCP795B12T-I/ST application, or MCP795B12T-I/ST equivalent, key selection considerations include its 32 kHz boot-up capability (MCP795BXX variant), VBAT switchover threshold (1.3–1.7 V), <700 nA timekeeping current at 1.8 V, 10 MHz SPI interface, and dual event detect inputs (EVHS/EVLS) with configurable debounce and pulse counting.

Technical Context

The MCP795B12T-I/ST implements a crystal-based RTCC with automatic leap-year correction, 24-/12-hour format support, and hundredth-of-second resolution. Its oscillator requires an external 32.768 kHz tuning fork crystal and load capacitors, while the CLKOUT/BOOT pin delivers a 32 kHz output at power-up - a distinguishing feature of the MCP795BXX family versus MCP795WXX.

It integrates a programmable watchdog timer with dedicated WDO pin, two event detect inputs (EVHS for high-speed pulse counting up to 32nd edge; EVLS with 31 ms or 500 ms debounce), and power-fail time-stamp logging that records both VCC failure and restoration timestamps in dedicated registers (0x18–0x1F and 0x1C–0x1F).

Key Specifications

Parameter	Value and Actual Design Meaning
VCC Range	1.8V to 5.5V - supports wide-input industrial and battery-powered systems without level-shifting.
VBAT Range	1.3V to 5.5V - enables reliable timekeeping and SRAM retention down to 1.3V backup supply.
Timekeeping Current	<700 nA @ 1.8V VBAT - extends coin-cell life beyond 10 years in typical backup configurations.
SPI Clock Speed	Up to 10 MHz - allows millisecond-resolution alarm programming and fast register/SRAM access.
Digital Trimming Range	±255 ppm in 1 ppm steps - enables field calibration to compensate for crystal aging and temperature drift.
EEPROM Endurance	1,000,000 erase/write cycles - ensures long-term reliability for firmware configuration storage.
Operating Temp	−40°C to +85°C (Industrial) - qualified for harsh environments including utility meters and industrial PLCs.

Pinout & Package

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

Pin/Terminal	Circuit Role	Design Meaning
1 (X1)	Crystal input / external oscillator input	Drives internal oscillator; accepts 32.768 kHz crystal or CMOS clock signal; X2 must be NC if external clock used.
2 (X2)	Crystal output	Output node of internal oscillator circuit; connects to crystal's second terminal; not used with external clock.
3 (VBAT)	Backup power supply input	Provides continuous power to RTC registers and SRAM during VCC loss; switchover occurs at 1.3–1.7 V.
4 (WDO)	Watchdog timer open-drain output	Active-low pulse on overflow; requires external pull-up; sink current ≤10 mA; user-configurable pulse width.
5 (IRQ)	Shared interrupt/event output	Open-drain output asserted low on alarm or event detection; cleared only by software register write.
6 (CS)	Chip select input	Active-low SPI enable; forces standby mode when high; initiates internal write cycle on rising edge after write sequence.
7 (VSS)	Ground reference	Primary return path for VCC and digital I/O; must be low-impedance connection to minimize noise coupling.
8 (SCK)	SPI serial clock input	Master-generated clock; data latched on rising edge (SI), updated on falling edge (SO); max 10 MHz.
9 (SI)	SPI serial data input	Receives instructions (e.g., READ, EEWRITE), addresses, and data; MSb-first protocol.
10 (SO)	SPI serial data output	Tri-state output; drives data after falling SCK edge; high-impedance when CS is high.
11 (EVLS)	Low-speed event detect input	Debounced input (31 ms or 500 ms); edge-triggered; operates from VCC or VBAT; ideal for mechanical switches.
12 (EVHS)	High-speed event detect input	Pulse-counting input (1st/4th/16th/32nd edge); no debounce; supports frequency monitoring or encoder inputs.
13 (CLKOUT/BOOT)	Programmable clock output / boot-up clock	Push-pull output; defaults to 32 kHz at power-up (MCP795BXX-specific); configurable for 1 Hz, 4.096/8.192/32.768 kHz.
14 (VCC)	Main power supply input	Primary operating supply; powers all logic, SPI interface, and EEPROM writes; auto-switches to VBAT on dropout.

Key Features

Feature	Design Value
32 kHz boot-up clock on CLKOUT/BOOT	Guarantees immediate timing reference at power-on without waiting for crystal stabilization - unique to MCP795BXX variants.
Power-fail time-stamp logging	Automatically records timestamp at VCC failure and restoration into dedicated SRAM registers (0x18–0x1F), enabling outage duration analysis.
EUI-64™ unique ID in protected EEPROM	128-bit preprogrammed MAC address stored in locked memory space; accessible only after unlock sequence; eliminates board-level ID programming.
Dual event detect with independent configuration	EVHS supports high-frequency pulse counting (e.g., flow meter pulses); EVLS provides hardware debounce for noisy switch inputs - no MCU firmware overhead.
On-chip digital trimming	Adjusts RTC accuracy in ±255 ppm increments via CALIBRATION register (0x09) and CALSGN bit (0x03:7), eliminating external trim caps.

Applications

Smart Energy Metering	Industrial PLC Backup Clock
Use Scenario: Utility-grade electricity meter requiring accurate time-of-use billing and tamper-proof time logging across power outages. IC Role / Device Role / Timing Role: Primary real-time clock/calendar with battery-switchover, power-fail timestamping, and EUI-64™ identity for secure firmware updates. Use Value: Maintains sub-second time accuracy during grid interruptions; logs outage start/end times to SRAM; enables remote validation of meter uptime.	Use Scenario: Programmable logic controller needing deterministic timekeeping for scheduled I/O tasks and diagnostic logging during brownouts. IC Role / Device Role / Timing Role: Standalone RTCC providing synchronized time base to CPU via SPI; retains time and config in 64-byte SRAM during VCC loss. Use Value: Eliminates time drift between power cycles; supports alarm-driven task scheduling; reduces need for external RTC supervision.
Medical Infusion Pump Timer	Network Equipment Time Sync
Use Scenario: Battery-powered infusion pump requiring precise dose timing, audit trail, and fail-safe operation under intermittent AC power. IC Role / Device Role / Timing Role: Safety-critical time source with <700 nA VBAT current, dual alarms for therapy alerts, and EEPROM-stored calibration data. Use Value: Extends primary battery life >5 years; ensures dose interval compliance even during AC dropout; meets IEC 62304 traceability requirements.	Use Scenario: Carrier-grade Ethernet switch needing IEEE 1588 PTP grandmaster clock reference and persistent time sync after reboot. IC Role / Device Role / Timing Role: High-accuracy RTC feeding system clock; uses 32 kHz boot-up output to initialize PHY timing before full firmware load. Use Value: Reduces time-to-sync by 200+ ms vs. crystal warm-up delay; maintains NTP stratum-1 consistency across reboots and power cycles.

Smart Energy Metering

Industrial PLC Backup Clock

Use Scenario: Utility-grade electricity meter requiring accurate time-of-use billing and tamper-proof time logging across power outages.

IC Role / Device Role / Timing Role: Primary real-time clock/calendar with battery-switchover, power-fail timestamping, and EUI-64™ identity for secure firmware updates.

Use Value: Maintains sub-second time accuracy during grid interruptions; logs outage start/end times to SRAM; enables remote validation of meter uptime.

Use Scenario: Programmable logic controller needing deterministic timekeeping for scheduled I/O tasks and diagnostic logging during brownouts.

IC Role / Device Role / Timing Role: Standalone RTCC providing synchronized time base to CPU via SPI; retains time and config in 64-byte SRAM during VCC loss.

Use Value: Eliminates time drift between power cycles; supports alarm-driven task scheduling; reduces need for external RTC supervision.

Medical Infusion Pump Timer

Network Equipment Time Sync

Use Scenario: Battery-powered infusion pump requiring precise dose timing, audit trail, and fail-safe operation under intermittent AC power.

IC Role / Device Role / Timing Role: Safety-critical time source with <700 nA VBAT current, dual alarms for therapy alerts, and EEPROM-stored calibration data.

Use Value: Extends primary battery life >5 years; ensures dose interval compliance even during AC dropout; meets IEC 62304 traceability requirements.

Use Scenario: Carrier-grade Ethernet switch needing IEEE 1588 PTP grandmaster clock reference and persistent time sync after reboot.

IC Role / Device Role / Timing Role: High-accuracy RTC feeding system clock; uses 32 kHz boot-up output to initialize PHY timing before full firmware load.

Use Value: Reduces time-to-sync by 200+ ms vs. crystal warm-up delay; maintains NTP stratum-1 consistency across reboots and power cycles.

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
MCP795W12T-I/ST	No 32 kHz boot-up clock; identical EEPROM, SRAM, alarms, and trimming; same pinout and SPI interface.	Lacks power-on timing reference - requires software wait for crystal startup; unsuitable where immediate clock availability is critical.	Select MCP795W12T-I/ST only if boot-time clock output is unnecessary and cost optimization is prioritized.
DS3231M+	Integrated TCXO (±2 ppm accuracy); higher VCC current (~1.3 µA); no EVHS/EVLS inputs; different SPI command set and register map.	Better accuracy without calibration but lacks event detection, watchdog, and boot-clock features; requires PCB redesign due to 16-pin TDFN package.	Choose DS3231M+ only when absolute accuracy outweighs feature richness and pin compatibility.

Compared with MCP795W12T-I/ST, the MCP795B12T-I/ST adds guaranteed 32 kHz clock at power-up - eliminating startup delay - while retaining full functional equivalence elsewhere; versus DS3231M+, it trades TCXO precision for richer system integration (event detect, watchdog, EEPROM, boot clock) in a drop-in SOIC package.

Availability

MCP795B12T-I/ST is available at Aetrix Electronics and suitable for industrial metering, medical device timing, network equipment synchronization, and backup-power embedded systems requiring stable component supply across multi-year production cycles.

Supply support for MCP795B12T-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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and timing solutions, with broad industrial and automotive qualification coverage.

The MCP795XXX product line was designed for embedded systems requiring robust, feature-rich real-time clock functionality with battery backup, nonvolatile memory, and system supervision - targeting metering, control, and infrastructure applications.

FAQ

What is the key functional difference between MCP795B12T-I/ST and MCP795W12T-I/ST?

The MCP795B12T-I/ST provides a guaranteed 32 kHz clock output on the CLKOUT/BOOT pin at power-up, whereas the MCP795W12T-I/ST does not. This boot-clock feature eliminates crystal startup delay, enabling immediate timebase availability for time-critical initialization sequences. All other specifications - including SRAM, EEPROM, alarms, trimming, and pinout - are identical between the two parts.

Does MCP795B12T-I/ST support automatic leap-year correction and calendar adjustments?

Yes, the MCP795B12T-I/ST automatically adjusts for months with fewer than 31 days and performs leap-year correction through its internal calendar logic. It supports both 12-hour (with AM/PM) and 24-hour time formats, and stores date/time in BCD format across dedicated registers (0x00–0x07). No host MCU intervention is required for month-end or leap-day rollover.

How does the power-fail time-stamp feature work in MCP795B12T-I/ST?

The MCP795B12T-I/ST logs timestamps automatically when VCC fails (entering VBAT mode) and again when VCC is restored. These values are stored in dedicated SRAM registers: power-down time in addresses 0x18–0x1F, and power-up time in 0x1C–0x1F. The VBATEN bit (0x04:3) must be set to enable VBAT backup, and the VBAT pin must be connected to a valid backup source.

Can MCP795B12T-I/ST operate solely from VBAT without VCC applied?

No - the MCP795B12T-I/ST cannot perform SPI communication or EEPROM writes from VBAT alone. While timekeeping and SRAM retention function from VBAT (1.3–5.5 V), the SPI interface, alarms, event detects, and watchdog require VCC. VBAT-only operation is limited to maintaining RTC registers and SRAM contents during main power loss.

What is the purpose of the EVHS and EVLS pins on MCP795B12T-I/ST?

EVHS (pin 12) is a high-speed event input supporting pulse counting (1st, 4th, 16th, or 32nd edge) for applications like flow meters or encoders. EVLS (pin 11) is a low-speed input with programmable hardware debounce (31 ms or 500 ms), optimized for mechanical switch inputs. Both operate from VCC or VBAT and generate IRQ assertions without MCU polling overhead.

MCP795B12T-I/ST Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

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

MCP795B12T-I/ST FAQ

1.How can I place an order for MCP795B12T-I/ST through Aetrix?

Please submit a Request for Quotation (RFQ) for MCP795B12T-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 MCP795B12T-I/ST reliable?

The price and inventory of MCP795B12T-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 MCP795B12T-I/ST is usually 5 days.

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MCP795B12T-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MCP795B12T-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 MCP795B12T-I/ST?

For technical support, including MCP795B12T-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MCP795B12T-I/ST requirements.

6.How does Aetrix verify that MCP795B12T-I/ST is sourced from the original manufacturer or authorized distributors?

All MCP795B12T-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 MCP795B12T-I/ST meets industry standards.

7.What is the process for return or replacement of MCP795B12T-I/ST?

All MCP795B12T-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with MCP795B12T-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 MCP795B12T-I/ST part is unused and in its original packaging.

Return procedure for MCP795B12T-I/ST:

1.Submit a request within 90 days.

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

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