ISL12027IVZ

Real Time Clock Overview

The ISL12027IVZ is an obsolete Real Time Clock and Calendar IC manufactured by Renesas Electronics (formerly Intersil). It features an I2C interface, 512-bit EEPROM, and intelligent battery backup switching. The device operates on a main supply of 2.7V to 5.5V and a backup supply of 1.8V to 5.5V. Key electrical parameters include a maximum timekeeping current of 20µA at 5.5V and a battery supply current of 1000nA at 3.0V. It provides automatic leap year correction through 2099, two non-volatile alarms, and oscillator compensation with ±30ppm adjustment.

Real Time Clock Feature Summary

• I2C Interface: Supports 400kHz data transfer rate with open-drain SDA/SCL pins.
• Integrated Memory: Includes 512x8-bit EEPROM with 16-byte page write mode and BlockLock protection.
• Oscillator Compensation: Features internal feedback resistors and a 64-position digitally controlled trim capacitor for frequency adjustment.
• CPU Supervisor: Integrates Power-On Reset, Low Voltage Reset, and Watchdog Timer functions.

Real Time Clock Applications

• Utility Meters
• HVAC Equipment
• Network Routers, Hubs, Switches, Bridges
• Cellular Infrastructure Equipment
• POS Equipment

Real Time Clock Procurement Notes

The ISL12027IVZ is officially classified as obsolete and no longer available or supported by the manufacturer. No recommended replacement part number is provided in the datasheet. Verification of component authenticity and physical condition is critical when sourcing from secondary markets due to the end-of-life status.

Real Time Clock Selection Notes

Designers should note that the ISL12027 uses Legacy Mode settings, distinct from the ISL12027A Standard Mode. Applications requiring VBAT > VDD operation must utilize the ISL12027A variant. Selection requires confirming compatibility with the specific VRESET voltage level (4.38V for this suffix) and ensuring the host system supports the required I2C protocol and EEPROM write sequences.

Real Time Clock Part Context

This component belongs to the ISL12027 family of low-power real-time clocks. The 'IV' suffix indicates an 8-lead TSSOP package, while 'Z' denotes lead-free/RoHS compliance. The 'IVZ' suffix specifically corresponds to a VRESET threshold of 4.38V and a BSW bit default setting of 1.

Real Time Clock Replacement Considerations

The datasheet explicitly states there is no recommended replacement for this obsolete product. Engineers must evaluate alternative RTCs with similar I2C interfaces, EEPROM capacity, and package dimensions, while verifying power management logic differences between Legacy and Standard modes.

Real Time Clock FAQ

What is the function of the RESET pin?

The RESET pin is an open-drain active LOW output that notifies the host processor if the watchdog timer expires or if the VDD voltage drops below the VTRIP threshold.

How does the device handle battery backup switching?

The ISL12027 features intelligent battery backup switching that automatically transitions power between VDD and VBAT. The BSW bit default setting for this part is 1.

What is the data retention period for the EEPROM?

The EEPROM data retention is specified as 50 years at temperatures less than or equal to +75°C.