Renesas ISL12029IB27Z

Overview

ISL12029IB27Z from Intersil is a low-power real-time clock/calendar IC with integrated 512×8-bit EEPROM, dual non-volatile alarms, CPU supervisor (POR, watchdog timer, low-voltage reset), and I²C interface. It operates from 2.7V to 5.5V main supply and maintains timekeeping down to 1.8V on VBAT, supports automatic leap-year correction through 2099, and delivers 800nA battery current in backup mode - used in utility meters and industrial control systems requiring long-term timestamping and power-fail resilience.

For engineers reviewing the ISL12029IB27Z datasheet, ISL12029IB27Z pinout, ISL12029IB27Z application, or ISL12029IB27Z equivalent, key selection considerations include its VBAT trip point of 2.63V (Legacy Mode), 400kHz I²C compliance, 1Hz/4096Hz/32.768kHz selectable frequency output, and 50-year EEPROM data retention - critical for tamper-resistant logging and battery-backed configuration storage.

Technical Context

The ISL12029IB27Z implements a crystal-based RTC architecture using an external 32.768kHz quartz oscillator with on-chip digitally controlled trim capacitors (64-position) and six digital frequency adjustment settings (±30ppm). Its alarm logic supports second-, minute-, hour-, day-of-week-, date-, and month-based match conditions with repeat mode for periodic interrupts.

Power management includes intelligent VDD/VBAT switchover with 50mV hysteresis, a dedicated 2.63V reset threshold (VRESET), and watchdog timer with three timeout options (225ms/250ms/275ms). The I²C interface remains functional during battery backup when enabled via register control, and all RTC registers are latched during read to prevent mid-read corruption.

Key Specifications

Pinout & Package

ISL12029IB27Z is housed in a Pb-free 14-lead SOIC package (M14.15), with 0.150" body width and standard JEDEC MS-012AC footprint. Pin 1 is X1 (crystal input), pin 2 is X2 (crystal output), pins 3–5 and 10–11 are NC, pin 6 is open-drain RESET, pin 7 is GND, pin 8 is SDA (I²C bidirectional), pin 9 is SCL (I²C clock), pin 12 is IRQ/FOUT (multi-function open-drain), pin 13 is VBAT (backup supply), and pin 14 is VDD (main supply).

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS3231SN#T&R and PCF2129AATS/1, the ISL12029IB27Z uniquely combines EEPROM-based alarm persistence, hardware memory locking, and Legacy Mode VBAT switchover - making it optimal for cost-sensitive industrial meters where secure, long-term timestamping and brown-out resilience are prioritized over ultra-high oscillator accuracy.

Availability

ISL12029IB27Z is available at Aetrix Electronics and suitable for utility metering, HVAC control systems, and industrial test equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for ISL12029IB27Z 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 Corporation (now part of Renesas Electronics) is a U.S.-based semiconductor company specializing in precision analog, power management, and timing solutions for industrial, communications, and computing markets.

The ISL12029IB27Z belongs to Intersil's legacy RTC family designed for high-reliability, battery-backed timekeeping in metering and infrastructure applications - emphasizing low power, EEPROM integration, and robust power-fail handling over raw oscillator precision.

FAQ

What is the VBAT trip point and reset threshold for ISL12029IB27Z?

The ISL12029IB27Z has a VBAT mode threshold (VTRIP) of 2.6V nominal with 50mV hysteresis, and its reset voltage (VRESET) is fixed at 2.63V. This Legacy Mode setting ensures reliable switchover to backup power before main supply collapse and guarantees clean system reset during brown-out events - both values are factory-trimmed and specified over -40°C to +85°C.

Does ISL12029IB27Z support I²C communication during battery backup?

Yes, ISL12029IB27Z supports full I²C read/write operations during VBAT-only operation when the I²C-enable bit in the control register is set. This allows host microcontrollers to access RTC registers, alarms, and EEPROM without restoring VDD - critical for diagnostics and configuration updates in unpowered states.

How does the ISL12029IB27Z handle leap years and calendar accuracy?

The ISL12029IB27Z implements automatic leap-year correction through year 2099 using hardware logic that detects years divisible by 4. It also handles variable month lengths (28–31 days) and supports both 12-hour (AM/PM) and 24-hour time formats. Calendar registers update atomically, and all date/time reads are latched to prevent mid-read corruption.

What is the EEPROM endurance and retention specification for ISL12029IB27Z?

The ISL12029IB27Z integrates 512×8-bit EEPROM with guaranteed endurance of >2,000,000 write cycles per byte and 50-year data retention at ≤+75°C. BlockLock™ protection supports eight lock modes to safeguard critical sectors, and page-write (16-byte) and single-byte write modes provide flexibility for firmware and calibration data storage.

Can ISL12029IB27Z generate multiple clock outputs?

Yes, the IRQ/FOUT pin of ISL12029IB27Z can be configured via I²C to output 1Hz, 4096Hz, or 32.768kHz square waves - all derived from the internal 32.768kHz crystal oscillator. These outputs are open-drain and require external pull-up resistors; the 1Hz option is commonly used for microcontroller wake-up, while 32.768kHz supports clock distribution in low-power subsystems.