Renesas ISL12027IV27Z

Overview

ISL12027IV27Z from Intersil is a low-power real-time clock/calendar IC with integrated 512×8-bit EEPROM, two non-volatile alarms, on-chip oscillator compensation, CPU supervisor (POR/WDT), and intelligent battery backup switching. It operates from 2.7V to 5.5V main supply and retains timekeeping down to 1.8V on VBAT, uses an external 32.768kHz crystal, and delivers ±30ppm digital frequency adjustment. It is deployed in utility meters and HVAC equipment for accurate, long-term timestamping and configuration storage.

For engineers reviewing the ISL12027IV27Z datasheet, ISL12027IV27Z pinout, ISL12027IV27Z application, or ISL12027IV27Z equivalent, key selection considerations include its 8-pin TSSOP package, 2.63V VRESET threshold, 800nA battery current, I²C interface at 400kHz, and dual-alarm repeat mode support - all critical for battery-backed industrial timing systems requiring data retention and power-fail resilience.

Technical Context

The ISL12027IV27Z implements a fully autonomous RTC subsystem with separate volatile timekeeping registers (hours/minutes/seconds/date/month/year/day-of-week) and non-volatile alarm registers, all accessible via I²C. Its oscillator compensation includes a 64-position digitally controlled trim capacitor and six discrete frequency adjustment settings spanning ±30ppm, enabling calibration against temperature drift without external components.

Power management integrates legacy-mode battery switching (VBAT > VDD supported), a 250ms power-on reset delay, and a watchdog timer with three selectable timeout periods (225/250/275ms). The RESET pin is open-drain active-low and remains asserted during VDD brownout until return to VDD operation - not released in battery-only mode.

Key Specifications

Pinout & Package

ISL12027IV27Z is housed in an 8-lead Pb-free TSSOP package (Moisture Sensitivity Level 1, JEDEC-compliant reflow profile), optimized for compact industrial PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS3231M and PCF8563T, the ISL12027IV27Z uniquely balances ultra-low battery current (800nA), on-die oscillator compensation (±30ppm), and 512×8-bit BlockLock™ EEPROM - making it optimal for industrial meters and controllers needing long-life backup, field-calibratable accuracy, and secure parameter storage.

Availability

ISL12027IV27Z is available at Aetrix Electronics and suitable for utility meters, HVAC controllers, and network infrastructure requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for ISL12027IV27Z 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 company specializing in precision analog, power management, and timing solutions for industrial, communications, and computing markets.

The ISL12027IV27Z belongs to Intersil's real-time clock and supervisor product line, designed specifically for battery-backed industrial systems demanding high reliability, EEPROM-based configuration persistence, and robust power-fail response.

FAQ

What is the VBAT operating voltage range for reliable timekeeping in ISL12027IV27Z?

The ISL12027IV27Z guarantees full RTC and calendar functionality down to 1.8V on VBAT. Operation below 1.8V is not specified and may result in timekeeping failure after VDD power-down cycles. At VBAT = 1.8V, battery supply current is 800–1000nA, supporting multi-year coin-cell life. The device does not operate from VBAT alone if VDD is present and above VTRIP - switchover is automatic and seamless.

Does ISL12027IV27Z support I²C communication during battery backup mode?

No - I²C communication is disabled during battery backup mode (when BAT = 1 in Status Register). The SCL and SDA pins are high-impedance, and no ACK is generated. This prevents bus contention and preserves battery life. Communication resumes only after VDD returns above VTRIP and the device exits battery mode. This behavior is documented in "I²C Communications During Battery Backup and LVR Operation" (page 24 of FN8232 Rev 9.00).

How does the oscillator compensation work in ISL12027IV27Z?

The ISL12027IV27Z integrates a 64-position digitally controlled trim capacitor and six discrete frequency adjustment settings (±30ppm total range) to calibrate the 32.768kHz crystal oscillator. Compensation is applied via the ATR register and requires no external components. It corrects for temperature-induced crystal drift and enables factory or field calibration - unlike basic RTCs that rely solely on crystal tolerance.

What is the function of the RESET pin in ISL12027IV27Z, and how does it behave during brownout?

The RESET pin is an open-drain active-low output signaling either VDD brownout (below 2.63V) or watchdog timeout. During brownout, RESET asserts LOW and remains LOW until VDD recovers *and* the device exits battery mode - it does not release while operating solely on VBAT. This ensures host processors reset only when stable VDD is restored. A 5kΩ pull-up resistor is recommended; unused RESET should be tied to GND.

Can ISL12027IV27Z store configuration data reliably over the product lifetime?

Yes - the ISL12027IV27Z features 512×8-bit EEPROM with BlockLock™ protection, rated for >2,000,000 write cycles per byte and 50 years of data retention at ≤+75°C. Critical parameters (e.g., calibration offsets, alarm schedules) can be stored in locked pages, while user data occupies unlocked regions. Page-write (16-byte) and single-byte write modes are both supported, with tWC = 12–20ms non-volatile write cycle time.