Microchip Technology MCP795B22T-I/ST

Overview

MCP795B22T-I/ST from Microchip Technology is a SPI real-time clock/calendar (RTCC) IC with integrated 2 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 32.768 kHz crystal or external clock input, provides 32 kHz boot-up clock at power-up, and features dual programmable alarms, digital trimming (±255 ppm in 1 ppm steps), and power-fail time-stamping. Used in industrial metering, backup power systems, and data loggers requiring precise timestamped event capture.

For engineers reviewing the MCP795B22T-I/ST datasheet, MCP795B22T-I/ST pinout, MCP795B22T-I/ST application, or MCP795B22T-I/ST equivalent, key selection criteria include VBAT switchover behavior (1.3–1.7 V trip point), 700 nA timekeeping current at 1.8 V, 10 MHz SPI interface timing across 1.8–5.5 V, 32 kHz boot-clock capability, and EUI-64™ MAC address preprogramming.

Technical Context

The MCP795B22T-I/ST implements a fully autonomous RTCC core with hardware oscillator control, automatic VCC-to-VBAT switchover, and on-chip digital calibration logic that adjusts timebase error in real time using an 8-bit signed calibration register (±510 clocks/minute). Its dual-event detection system includes EVHS (pulse-counting for 1st/4th/16th/32nd edge) and EVLS (debounced inputs with 31 ms or 500 ms filters), both operable from VCC or VBAT.

It integrates three nonvolatile memory blocks: 2 Kbit EEPROM (1M endurance, page write up to 8 bytes), 64-byte SRAM (battery-backed), and 128-bit protected ID space (preprogrammed EUI-64™). The watchdog timer offers dual retrigger via SPI or EVHS input, with user-selectable pulse duration and dedicated WDO open-drain output.

Key Specifications

Pinout & Package

Package: 14-lead SOIC (Small Outline Integrated Circuit), 150 mil width, RoHS-compliant, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP795W22T-I/ST and DS3231SN#T&R, the MCP795B22T-I/ST uniquely combines boot-clock readiness, dual-event detection, and cryptographically secure EUI-64™ identity - making it optimal for resource-constrained, time-critical, and identity-aware embedded systems.

Availability

MCP795B22T-I/ST is available at Aetrix Electronics and suitable for industrial metering, secure IoT gateways, and medical data loggers requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for MCP795B22T-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 semiconductor manufacturer specializing in microcontrollers, analog devices, and timing solutions, with global design centers and manufacturing facilities.

The MCP795BXX family was designed for industrial and embedded systems requiring autonomous, battery-backed timekeeping with integrated memory, event detection, and secure identity - targeting smart meters, data loggers, and connected medical devices.

FAQ

What is the function of the CLKOUT/BOOT pin on the MCP795B22T-I/ST?

The CLKOUT/BOOT pin on the MCP795B22T-I/ST serves dual roles: as a configurable clock output (1 Hz / 4.096 kHz / 8.192 kHz / 32.768 kHz) when SQWE is enabled, and as a dedicated 32 kHz boot-up clock source immediately after power-on - a feature exclusive to the MCP795BXX series and confirmed in the Device Selection Table for MCP795B22.

Does the MCP795B22T-I/ST support automatic VCC-to-VBAT switchover, and what is its voltage threshold?

Yes, the MCP795B22T-I/ST supports automatic switchover from VCC to VBAT. Its VBAT changeover threshold is specified as 1.3 V (min) to 1.7 V (max), with 1.5 V typical at 25°C (Table 1-1, Param D013). This ensures seamless timekeeping and SRAM retention during main supply interruption without host intervention.

How does the MCP795B22T-I/ST implement power-fail time-stamping, and where is the data stored?

The MCP795B22T-I/ST automatically logs timestamps at the moment VCC fails and again when VCC is restored. These timestamps are stored in dedicated Power-down and Power-Up Time-stamp Registers (addresses 0x18–0x1F and 0x1C–0x1F respectively), as defined in the RTCC Register Map (Table 4-1), enabling precise outage duration calculation in energy metering applications.

What type of unique ID is provided in the MCP795B22T-I/ST, and how is it accessed?

The MCP795B22T-I/ST includes a factory-programmed 128-bit EUI-64™ MAC address in a protected EEPROM region. It is accessed via the IDREAD instruction (0011 0011) after unlocking the ID locations using the UNLOCK instruction (0001 0100), as documented in the Instruction Set Summary (Table 3-1) and Memory Map (Figure 2-2).

What are the key differences between the MCP795B22T-I/ST and the MCP795W22T-I/ST?

The primary difference is the presence of the 32 kHz boot-up clock on the CLKOUT/BOOT pin - available only in MCP795BXX variants like the MCP795B22T-I/ST and absent in MCP795WXX parts such as the MCP795W22T-I/ST. All other features - 2 Kbit EEPROM, 64-byte SRAM, EUI-64™ ID, alarms, calibration, and event detection - are identical per the Device Selection Table.