S-35390A-I8T1G

Real Time Clock Overview

The S-35390A-I8T1G is a CMOS 2-wire real-time clock IC manufactured by ABLIC Inc. It operates within a wide voltage range of 1.3 V to 5.5 V, supporting both main supply and backup battery applications. The device features low current consumption of 0.25 µA typical at 3.0 V during timekeeping. It includes an internal constant-voltage circuit and a built-in 32.768 kHz crystal oscillation circuit with internal capacitance. The IC provides auto-calendar functionality up to the year 2099 with automatic leap year calculation. Communication is handled via a standard I²C-bus interface.

Real Time Clock Feature Summary

• Low current consumption: 0.25 µA typ. (VDD = 3.0 V, Ta = +25°C)
• Wide operating voltage range: 1.3 V to 5.5 V
• Built-in clock correction function for frequency deviation compensation
• Built-in free user register for data backup
• Auto calendar up to 2099 with automatic leap year calculation

Real Time Clock Applications

• Mobile game devices
• Digital still cameras
• Electronic power meters
• DVD recorders
• TV and VCR systems

Real Time Clock Procurement Notes

Verify that the ordering suffix 'I8T1' corresponds to the SNT-8A package type as defined in the product name structure. Confirm the environmental code 'G' meets specific lead-free requirements, noting that 'U' denotes Sn 100% halogen-free compliance. Ensure the supplier documentation aligns with the official ABLIC datasheet specifications for this part number.

Real Time Clock Selection Notes

Select the S-35390A-I8T1G when an SNT-8A package is required for the design. The device supports I²C communication at frequencies up to 400 kHz. Ensure external quartz crystals match the recommended CL value of 6 pF. The internal oscillation capacitance is approximately 8 pF, requiring an external capacitor on the XIN pin if necessary for load matching.

Real Time Clock Part Context

This component belongs to the S-35390A series of 2-wire real-time clocks from ABLIC Inc. The series offers variations in packaging, including 8-Pin SOP (JEDEC), 8-Pin TSSOP, and SNT-8A. The core functionality remains consistent across packages, providing timekeeping, alarm interrupts, and user-accessible registers via the I²C interface.

Real Time Clock Replacement Considerations

Direct substitutes include other S-35390A variants with different packages, such as S-35390A-T8T1G (TSSOP) or S-35390A-J8T1G (SOP). Verify pin compatibility and package dimensions before substitution. Cross-referencing with Seiko Instruments parts may be relevant due to historical lineage, but electrical parameters must be confirmed against the specific ABLIC datasheet.

Real Time Clock FAQ

What is the purpose of the RESET bit in Status Register 1?

The RESET bit (B7) is write-only. Setting it to '1' initializes the internal IC. This action clears the POC flag and resets most registers to their default states, ensuring the device starts in a known condition.

How does the low power supply voltage detection work?

The BLD flag (B1 in Status Register 1) is set to '1' when the power supply voltage drops to or below the detection voltage (VDET). Once set, it remains '1' even if voltage recovers, indicating a potential power failure event until the circuit is initialized.

Can the INT1 and INT2 pins output frequencies other than alarms?

Yes. By configuring Status Register 2, users can set INT1 and INT2 to output user-defined frequencies (1 Hz, 2 Hz, 4 Hz, 8 Hz, 16 Hz) or minute-periodical interrupts. The frequency is determined by bits in the corresponding INT register.