Microchip Technology MCP795B11-I/ST

Overview

MCP795B11-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-48™ unique ID, and 32 kHz boot-up clock at power-up. It supports digital trimming (±255 ppm), dual programmable alarms, power-fail time-stamping, and operates from 1.8V to 5.5V VCC or 1.3V to 5.5V VBAT for industrial embedded systems requiring accurate timekeeping during main power loss.

For engineers reviewing the MCP795B11-I/ST datasheet, MCP795B11-I/ST pinout, MCP795B11-I/ST application, or MCP795B11-I/ST equivalent, key selection criteria include its 32 kHz boot-up capability, VBAT timekeeping current <700 nA @ 1.8V, 10 MHz SPI interface, dual event detect inputs (EVHS/EVLS), and integrated watchdog timer with dedicated WDO pin.

Technical Context

The MCP795B11-I/ST implements a crystal-based RTCC with on-chip oscillator driving X1/X2 pins, supporting external 32.768 kHz tuning fork crystals and load capacitors. Its 32 kHz boot-up clock on CLKOUT/BOOT enables immediate timing reference at power-on without waiting for crystal stabilization.

It integrates dual alarm registers (Alarm 0 with seconds resolution, Alarm 1 with hundredths-of-second resolution), programmable open-drain IRQ output shared across alarms and event detects, and hardware-controlled VBAT switchover with automatic time-stamp logging on VCC fail/restore - all accessible via SPI commands including EEREAD, EEWRITE, READ, WRITE, and CLRWDT.

Key Specifications

Pinout & Package

Package: 14-Lead SOIC (Small Outline Integrated Circuit), surface-mount, 150 mil width. Pin-compatible with TSSOP variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP795W11-I/ST, the MCP795B11-I/ST adds critical boot-time timing capability without layout change; versus DS3231M+, it trades ±2 ppm accuracy for richer system integration (event inputs, watchdog pin, SPI speed) and lower backup current - making it optimal for resource-constrained industrial hosts needing deterministic startup and peripheral offload.

Availability

MCP795B11-I/ST is available at Aetrix Electronics and suitable for smart energy metering, industrial PLC controllers, medical infusion pumps, and building automation gateways requiring stable component supply across long-lifecycle deployments.

Supply support for MCP795B11-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 microcontrollers, analog, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with high-reliability silicon and development tools.

The MCP795XXX family delivers integrated real-time clock/calendar functionality with battery switchover, nonvolatile memory, and system peripherals - designed specifically for industrial and medical applications demanding robust timekeeping under variable power conditions.

FAQ

What is the primary function of the MCP795B11-I/ST?

The MCP795B11-I/ST is a SPI real-time clock/calendar IC that maintains accurate time and date across power cycles using battery backup, supports dual alarms with hundredths-of-second resolution, and integrates 64-byte SRAM, 1 Kbit EEPROM, and EUI-48™ unique ID. Its 32 kHz boot-up clock on CLKOUT/BOOT provides immediate timing reference at power-on - a defining feature distinguishing it from the MCP795WXX series.

Does the MCP795B11-I/ST require an external crystal?

Yes, the MCP795B11-I/ST requires an external 32.768 kHz tuning fork crystal connected between X1 and X2 pins for standard operation. It also supports external CMOS clock input on X1 (with X2 left unconnected) via the EXTOSC bit in Control Register 0x08. The crystal oscillator is digitally trimmable over ±255 ppm in 1 ppm steps to compensate for frequency drift.

How does the power-fail time-stamp feature work in the MCP795B11-I/ST?

The MCP795B11-I/ST automatically logs timestamps when VCC fails (entering VBAT mode) and when VCC is restored (reverting to main power), storing both values in dedicated Power-down and Power-Up Time-stamp Registers (0x18–0x1F). This occurs without host intervention and is enabled by default upon VBAT switchover - providing precise outage duration data for diagnostics and compliance reporting in the MCP795B11-I/ST.

What are the key differences between MCP795B11-I/ST and MCP795W11-I/ST?

The MCP795B11-I/ST includes a 32 kHz boot-up clock on CLKOUT/BOOT at power-on, while the MCP795W11-I/ST does not. Both share identical 64-byte SRAM, 1 Kbit EEPROM, EUI-48™ ID, pinout, and SPI interface. The boot-clock feature eliminates startup delay in time-critical applications - making MCP795B11-I/ST the preferred choice where deterministic initial timing is required.

Can the MCP795B11-I/ST operate solely from VBAT without VCC applied?

Yes, the MCP795B11-I/ST can maintain timekeeping and retain SRAM contents using only VBAT (1.3V–5.5V) when VCC is absent, provided the VBATEN bit (0x04:3) is set. However, full functionality - including SPI communication, EEPROM writes, alarm generation, and event detection - requires VCC. EVHS and EVLS inputs remain active from VBAT, enabling basic event capture during backup mode in the MCP795B11-I/ST.