Renesas X1228S14-2.7T1

Overview

X1228S14-2.7T1 from Intersil is a 4K-bit (512 × 8) real-time clock/calendar with integrated CPU supervisor, 2-wire I²C-compatible interface, nonvolatile dual alarms, and 512-byte EEPROM. It operates from 2.7V to 5.5V, delivers 1.25µA typical timekeeping current at VBACK = 1.8V, supports ±30ppm digital oscillator trim, and provides programmable frequency output (1Hz/4096Hz/32.768kHz) or interrupt signaling via PHZ/IRQ - used in utility meters and HVAC equipment for accurate timestamping and power-fail resilience.

For engineers reviewing the X1228S14-2.7T1 datasheet, X1228S14-2.7T1 pinout, X1228S14-2.7T1 application, or X1228S14-2.7T1 equivalent, key selection criteria include its 14-pin SOIC package, user-programmable VTRIP threshold (2.85V ±100mV), dual nonvolatile alarm registers with repeat mode, on-chip oscillator compensation, and BlockLock™ EEPROM protection - all verified per FN8100 Rev 4.00.

Technical Context

The X1228S14-2.7T1 integrates a 32.768kHz crystal oscillator with internal feedback resistor, 64-position digitally controlled trim capacitor, and six digital frequency adjustment settings (±30ppm). Its RTC maintains BCD-encoded time/date registers with automatic leap-year correction through 2099 and handles month-end rollover including February 29.

CPU supervision includes power-on reset (250ms typical delay), low-voltage sense with factory-trimmed 2.85V ±100mV trip point (reprogrammable), and watchdog timer with three selectable timeouts (0.25s/0.75s/1.75s). The device switches autonomously between VCC and VBACK (1.8–5.5V) using analog power-control circuitry with defined switchover thresholds (VCB = VBACK − 0.2V, VBC = VBACK + 0.2V).

Key Specifications

Pinout & Package

Package: 14-lead SOIC (MDP0027), RoHS-compliant Pb-free plus anneal finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISL12028IRZ-T7A and DS1339U-33+T&R, X1228S14-2.7T1 uniquely combines programmable VTRIP, on-die oscillator trim, dual nonvolatile alarms, and 512-byte BlockLock™ EEPROM in a single 14-pin SOIC - making it optimal for industrial metering and embedded systems needing self-contained time supervision without layout or firmware redesign.

Availability

X1228S14-2.7T1 is available at Aetrix Electronics and suitable for utility metering, HVAC control, and set-top box design requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for X1228S14-2.7T1 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

Intersil (now part of Renesas Electronics) is a semiconductor manufacturer specializing in precision analog, power management, and timing solutions for industrial, communications, and computing markets.

The X1228 product line was designed for embedded systems requiring integrated real-time clock, CPU supervision, and nonvolatile memory - targeting applications where board space, power efficiency, and timekeeping reliability are critical constraints.

FAQ

What is the VTRIP voltage specification for X1228S14-2.7T1?

The X1228S14-2.7T1 has a factory-programmed VTRIP threshold of 2.85V ±100mV, which triggers the RESET output when VCC falls below this level. This value is user-reprogrammable within a 2.75V to 2.95V range using a 15V programming voltage applied to VCC during the VTRIP programming sequence defined in the FN8100 datasheet. The X1228S14-2.7T1 maintains full functionality across its 2.7–5.5V operating range.

Does X1228S14-2.7T1 support I²C Fast Mode?

Yes, X1228S14-2.7T1 supports I²C Fast Mode at 400kHz, as confirmed by AC timing parameters in the FN8100 datasheet (tLOW = 1.3µs min, tHIGH = 0.6µs min, fSCL = 400kHz max). Its SDA pin features slope-controlled pull-down circuitry and open-drain output, while SCL uses an always-active CMOS input buffer - both compliant with I²C-bus specification revision 3.0. The X1228S14-2.7T1 does not support High-Speed Mode (3.4MHz).

How does the oscillator compensation work in X1228S14-2.7T1?

X1228S14-2.7T1 implements on-chip oscillator compensation using a 64-position digitally controlled trim capacitor and six discrete digital frequency adjustment settings that collectively provide ±30ppm tuning range. This eliminates the need for external load capacitors or manual crystal trimming. Compensation is applied automatically during startup and can be adjusted in-system via register writes to the oscillator control registers. The X1228S14-2.7T1 achieves stable 32.768kHz operation with standard low-cost crystals like the Citizen CFS206-32.768KDZF.

Can X1228S14-2.7T1 operate solely on VBACK without VCC?

Yes, X1228S14-2.7T1 remains fully operational on VBACK alone within the 1.8V to 5.5V range, maintaining RTC, calendar, alarms, and EEPROM functionality. When VCC is absent or below VBACK − 0.2V, the internal power switch routes VBACK to all internal circuits. The X1228S14-2.7T1 draws only 1.25µA typical at VBACK = 1.8V, enabling multi-year operation from a CR2032 coin cell. VCC must be present only for I²C communication or nonvolatile writes.

What EEPROM protection modes does X1228S14-2.7T1 offer?

X1228S14-2.7T1 implements BlockLock™ protection with eight distinct modes controlled by BP2/BP1/BP0 bits in the BL register (address 0010h). These modes allow selective write-protection of EEPROM blocks ranging from full array lock to individual 64-byte page locks. Protection persists across power cycles and is enforced in hardware - preventing accidental or malicious overwrites of critical calibration or configuration data stored in the X1228S14-2.7T1's 512-byte EEPROM array.