Renesas X1228S14-4.5A

Overview

X1228S14-4.5A 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, features ±30ppm digital oscillator compensation, 1.25µA typical timekeeping current at VBACK = 1.8V, and supports battery or supercap backup. It is used in utility meters and network infrastructure equipment for accurate time stamping and system reset supervision.

For engineers reviewing the X1228S14-4.5A datasheet, X1228S14-4.5A pinout, X1228S14-4.5A application, or X1228S14-4.5A equivalent, key selection considerations include its 4.63V ±112mV reset threshold, 14-lead SOIC package, 400kHz I²C interface, dual programmable alarms with repeat mode, and on-chip oscillator trim capability for crystal accuracy calibration.

Technical Context

The X1228S14-4.5A integrates a 32.768kHz crystal-based RTC with leap-year correction through 2099, two independent nonvolatile alarm registers with per-field enable bits (second/minute/hour/day/month/year), and a programmable frequency/interrupt output (PHZ/IRQ) supporting 1Hz/4096Hz/32.768kHz or active-low IRQ assertion. Its oscillator includes a 64-position digitally controlled trim capacitor and six digital frequency adjustment settings.

CPU supervision comprises a power-on reset with ~250ms timeout, user-reprogrammable VTRIP (4.63V ±112mV), watchdog timer with three selectable timeouts (0.25s/0.75s/1.75s), and automatic VCC/VBACK switchover at VBACK − 0.2V. The device retains full RTC operation down to 1.8V on VBACK and supports EEPROM block-lock protection across eight modes.

Key Specifications

Pinout & Package

Package: 14-lead SOIC (MDP0027), 150 mil width, RoHS-compliant Pb-free plus anneal option available.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISL12028IRZ-T7A and DS1339U-33+T&R, the X1228S14-4.5A uniquely combines reprogrammable VTRIP, dual nonvolatile alarms, on-chip oscillator trim, and 512-byte EEPROM in a single 14-pin SOIC - making it optimal for cost-sensitive, 5V industrial designs requiring full feature integration without layout change.

Availability

X1228S14-4.5A is available at Aetrix Electronics and suitable for utility metering, network infrastructure, HVAC control, and consumer electronics applications requiring stable component supply, long-term timekeeping accuracy, and integrated power supervision.

Supply support for X1228S14-4.5A 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 highly integrated, low-power RTCs with CPU supervision and nonvolatile memory - targeting metering, networking, and consumer electronics where board space and BOM count are constrained.

FAQ

What is the VTRIP voltage setting for X1228S14-4.5A?

The X1228S14-4.5A has a factory-programmed VTRIP of 4.63V ±112mV, optimized for 5V systems. This threshold is user-reprogrammable using a 14–16V programming voltage applied to VCC during the VTRIP programming sequence. Reprogramming does not require external components and is performed via the 2-wire interface using the AEh command sequence defined in the datasheet. The X1228S14-4.5A retains this setting across power cycles.

Does X1228S14-4.5A support battery backup, and what voltage range is acceptable on VBACK?

Yes, the X1228S14-4.5A supports battery or supercapacitor backup via the VBACK pin, which accepts 1.8V to 5.5V. When VCC drops below VBACK − 0.2V, the device automatically switches to VBACK and maintains full RTC, alarm, and supervisor functionality. At 1.8V VBACK, the X1228S14-4.5A draws only 1.25µA, enabling multi-year operation on standard CR2032 coin cells. The VBACK pin may be tied to ground if backup is unused.

How does the oscillator compensation work in X1228S14-4.5A?

The X1228S14-4.5A implements on-chip oscillator compensation using a 64-position digitally controlled trim capacitor and six coarse digital frequency adjustment settings (±30ppm). This eliminates the need for external load capacitors or manual crystal tuning. Compensation is applied directly to the internal oscillator circuit formed by X1/X2 and an external 32.768kHz crystal (e.g., Citizen CFS206). Calibration is performed via register writes to the oscillator control registers, and settings persist across power cycles.

Can X1228S14-4.5A generate a 1Hz output signal, and how is it configured?

Yes, the X1228S14-4.5A can generate a 1Hz output on the PHZ/IRQ pin. Configuration is done by writing FO1=0 and FO0=0 to address 0011h in the Clock Control Memory map. The PHZ/IRQ pin then outputs a CMOS-compatible 1Hz square wave. This function is mutually exclusive with the interrupt mode - when enabled as frequency output, alarm events do not assert PHZ/IRQ as an interrupt. The 1Hz signal remains active during VBACK-only operation.

What is the EEPROM endurance and data retention specification for X1228S14-4.5A?

The X1228S14-4.5A provides 512 × 8 bits of EEPROM with guaranteed endurance of 100,000 write/erase cycles per byte and data retention of 100 years at +25°C. It supports both single-byte and 64-byte page write modes. BlockLock™ protection allows eight independent lock configurations to prevent accidental writes to critical sectors while leaving user areas freely writable. All EEPROM operations are nonvolatile and retain data during power loss.