Microchip Technology MCP795B20T-I/ST

Overview

MCP795B20T-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 dual programmable alarms. 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 on power-up, and operates from 1.8V–5.5V VCC with <700 nA VBAT timekeeping current at 1.8V - used in industrial metering, backup power systems, and data loggers requiring timestamped event capture.

For engineers reviewing the MCP795B20T-I/ST datasheet, MCP795B20T-I/ST pinout, MCP795B20T-I/ST application, or MCP795B20T-I/ST equivalent, key selection criteria include its 32 kHz boot-up capability (distinguishing it from MCP795WXX variants), digital trimming (±255 ppm in 1 ppm steps), power-fail time-stamping, and dual event detect inputs (EVHS/EVLS) with configurable debounce and pulse counting.

Technical Context

The MCP795B20T-I/ST implements a fully autonomous RTCC core with BCD-encoded time/date registers (0x00–0x1F), automatic leap-year correction, and 24-/12-hour format support. Its oscillator block accepts either a 32.768 kHz tuning fork crystal (X1/X2) or external CMOS clock, and features hardware-based VCC-to-VBAT switchover with time-stamp logging on both power loss and restoration.

It integrates a programmable watchdog timer (WDO output, dual-trigger via SPI or EVHS), two independent alarm engines (Alarm 0 with second-level resolution, Alarm 1 with hundredth-of-second resolution), and dual event detection paths: high-speed (EVHS, pulse-counting for 1st/4th/16th/32nd edge) and low-speed (EVLS, 31 ms or 500 ms debounce). All functions remain active under VBAT backup.

Key Specifications

Pinout & Package

Package: 14-lead SOIC (Small Outline Integrated Circuit), 150 mil width, RoHS-compliant, surface-mount.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP795W20T-I/ST, the MCP795B20T-I/ST adds guaranteed 32 kHz boot-up timing - eliminating startup delay in safety-critical or time-sensitive systems. Against DS3231SN#T&R, it trades absolute accuracy for integrated event detection, wider voltage range, and lower power in backup mode - making it optimal for resource-constrained, event-driven embedded designs.

Availability

MCP795B20T-I/ST is available at Aetrix Electronics and suitable for industrial metering, medical backup systems, and building automation controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MCP795B20T-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 devices, and timing solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The MCP795XXX family was designed specifically for embedded systems needing autonomous, low-power timekeeping with integrated memory and system supervision - targeting industrial, medical, and smart infrastructure applications.

FAQ

What is the key functional difference between MCP795B20T-I/ST and MCP795W20T-I/ST?

The MCP795B20T-I/ST provides a guaranteed 32 kHz clock output on the CLKOUT/BOOT pin at power-up, whereas the MCP795W20T-I/ST does not. This boot-up clock enables immediate system timing before firmware initializes the oscillator - a critical feature for fail-safe or time-critical applications. All other specifications including EEPROM size, SRAM, alarms, trimming, and pinout are identical between the two parts.

Does MCP795B20T-I/ST require an external crystal to operate?

Yes, the MCP795B20T-I/ST requires an external 32.768 kHz tuning fork crystal connected between X1 and X2 pins for standard operation. However, it also supports external CMOS clock input on X1 (with X2 left unconnected) via the EXTOSC bit (Control Register 0x08, bit 3), enabling crystal-free designs when a stable 32.768 kHz signal is already available in the system.

How does the power-fail time-stamping feature work in MCP795B20T-I/ST?

The MCP795B20T-I/ST automatically logs the exact time of VCC failure and restoration in dedicated registers (0x18–0x1F). When VCC drops below the switchover threshold (~1.5 V), the VBAT bit (Register 0x04, bit 4) is set and the current time is written to the power-down timestamp registers. Upon VCC recovery, the time is captured again in the power-up registers - all without host processor intervention.

Can MCP795B20T-I/ST generate multiple clock frequencies on the CLKOUT/BOOT pin?

Yes, the MCP795B20T-I/ST can generate 1 Hz, 4.096 kHz, 8.192 kHz, or 32.768 kHz on the CLKOUT/BOOT pin via the RS2:RS0 bits (Control Register 0x08, bits 2:0). The 32 kHz output is enabled by default at power-up for MCP795BXX variants. The SQWE bit (0x08, bit 6) must be set to enable any divided output, and calibration adjustments apply to all frequencies.

What is the endurance rating of the EEPROM in MCP795B20T-I/ST?

The EEPROM in MCP795B20T-I/ST is rated for 1,000,000 erase/write cycles, as specified in the datasheet (Table 1-2, Note 2). This endurance applies to both the main 2 Kbit array and the protected 128-bit Unique ID space. Write operations are page-based (up to 8 bytes per page), and software block write-protection (¼, ½, or full array) helps extend effective lifetime in field applications.