Real-time Clock (RTC) ICs


Real-time clock ICs operate as the clock in various devices. This clock function operates even when the power is turned off. In portable devices, it is important to reduce the current consumption of the real-time clock IC to extend the battery life. SII Semiconductor Corporation’s real-time clock ICs have a time-keeping current consumption of 0.25 µA and a time-keeping operating voltage of 1.1 V, which enables a much longer battery life. SII Semiconductor Corporation also offers various total-system solutions, such as high-accuracy clock correction, constant output of 32 kHz, wakeup signals, expanded alarms and 24-bit binary up-counters. SII Semiconductor Corporation’s real-time clock ICs are world’s smallest due to the employment of small WLP and SNT packages, enabling users to streamline their devices.

1. Low current consumption of 0.25 μA

Data taken from SII Semiconductor Corporation market research.SII Semiconductor Corporation has achieved a low current consumption of 0.25 µA and a low-voltage operation of 1.1 V. When using a rechargeable lithium ion battery (3.4 mAh) for backup, long-time driving of up to 13,000 hours is possible. Users are able to use smaller batteries, promoting high-density mounting.

2. High-accuracy clock correction

Temperature - Frequency deviation graphThe frequency deviation of a crystal oscillator can be corrected over a wide range with high accuracy at a minimum resolution of 1 ppm. By combining the real-time clock IC with a temperature sensor IC, the value of clock correction can be set according to the temperature change, enabling accurate correction if the clock becomes fast or slow.

3. Various solutions such as constant output of 32 kHz

Constant output of 32 kHz● Constant output of 32 kHz (clock pulse of 32.768 kHz output to CPU)

A 32.768 kHz clock is output to the CPU or other devices from an oscillator built into the RTC. This output makes a crystal oscillator unnecessary, reducing the number of parts.

The number of the SW input pins depends on the product.● The CPU is started by a wakeup signal A wakeup signal (active high) is sent to start the CPU by an input from the SW input pin or alarm interrupt. This can lower the power consumption of the entire system.

● Expanded alarm interrupt function, long-period setting SII Semiconductor Corporation’s real-time clock ICs not only have the standard day-of-the-week, hour and minute alarm interrupt functions; they also have alarm functions for the year, month and day.

● Counts up to about 30 years using 24-bit binary up-counter The 24-bit binary up-counter counts up every 60 seconds after power-on. Users are able to ascertain the elapsed time up to about 30 years.

4. The world’s smallest packages

WLP-12A, WLP-16A, SNT-8AUsing our real-time clock ICs with their small WLP and SNT packages makes the volume/area for mounting much smaller compared to conventional products, enabling high-density mounting.

WLP-12A: 1.97 x 1.84 x 0.6 mm WLP-16A: 1.97 x 2.13 x 0.6 mm SNT-8A: 2.5 x 2.0 x 0.5 mm