ISL12027AIV27Z-T

Real Time Clock Overview

The ISL12027AIV27Z-T is a low-power real-time clock/calendar integrated circuit manufactured by Renesas Electronics. It features an I²C interface, 512x8-bit EEPROM with BlockLock protection, 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 1.2µA max at 3.0V. It includes two non-volatile alarms, a watchdog timer, and on-chip oscillator compensation for ±30ppm accuracy.

Real Time Clock Feature Summary

• I²C Bus Interface: Supports 400kHz data transfer rate with open-drain SDA/SCL pins.
• On-Chip Oscillator Compensation: Features internal feedback resistors, trim capacitors, and digital frequency adjustment settings.
• Integrated Memory: Includes 512x8-bit EEPROM with 16-byte page write mode and 8 modes of BlockLock protection.
• CPU Supervisor Functions: Provides Power-On Reset (POR), Low Voltage Reset (LVR), and Watchdog Timer (WDT) capabilities.

Real Time Clock Applications

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

Real Time Clock Procurement Notes

The ISL12027AIV27Z-T is classified as an obsolete product with no recommended replacement available from the manufacturer. Verification of component authenticity and condition is critical when sourcing from secondary markets. The '-T' suffix indicates tape and reel packaging; confirm reel specifications via technical brief TB347 if required for automated assembly processes.

Real Time Clock Selection Notes

Select the ISL12027A variant specifically if the application requires VBAT > VDD operation, as it utilizes Standard Mode power control settings distinct from the Legacy Mode of the standard ISL12027. Ensure the external crystal matches the required load capacitance for optimal accuracy within the -40°C to +85°C operating temperature range.

Real Time Clock Part Context

This component belongs to the ISL12027 family of real-time clocks. The 'ISL12027A' designation denotes specific power control settings optimized for scenarios where backup voltage exceeds main supply voltage. The 'IV' package code corresponds to the 8-lead TSSOP form factor, while the '27' indicates a VRESET threshold of approximately 2.92V.

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 integration, and backup switching capabilities, ensuring compatibility with existing firmware and hardware constraints.

Real Time Clock FAQ

["What is the difference between ISL12027 and ISL12027A regarding power control?","The ISL12027 uses Legacy Mode settings, whereas the ISL12027A uses Standard Mode settings. Applications requiring VBAT > VDD operation necessitate the use of the ISL12027A."]

["How does the device handle time updates during a read operation?","The device latches the time into a separate buffer upon the falling edge of the clock on the ACK bit prior to data output. This prevents the clock from changing during the read operation, although the internal clock continues to run."]

["What are the requirements for writing to the Clock/Control Registers?","Writes to the CCR require both the WEL (Write Enable Latch) and RWEL (Register Write Enable Latch) bits to be set in a specific sequence using the Status Register. Writes do not cause a non-volatile cycle unless they target the EEPROM array."]