NXP's PCF2123 and PCF8523 are ultra low power real time clocks optimized for energy critical applications. The PCF85063 is a low power real time clock in a tiny package at a very competitive price.
PCF85063: Miniaturized, state-of-the-art RTC
The NXP PCF85063 offers precise timing in a small, low-power format. It is well suited for a wide range of applications. Aside from acting as a reference timer or tracking the actual time and date, the device can be used for power management, where the device wakes the microcontroller from hibernation mode, or as a system reference clock for a PLL input. It can serve as a watchdog or countdown timer, and can be used as an activation timer to start measurements or initiate other functions.
The device is available in three versions. The TP version tracks time and date and has an I2C Fast-mode interface. It offers electronic tuning and can be configured for a frequency output and an interrupt every 30 or 60 seconds. It is housed in a HWSON8 that measures only 2 x 3 x 0.8 mm.
The -ATL and -BTL versions add an alarm facility, a countdown timer, and a clock-out enable pin. The -ATL version is equipped with an I2C Fast-mode interface, while the -BTL has a 3-line SPI interface. Both devices are housed in an HXSON10 package that measures just 2.6 x 2.6 x 0.5 mm.
PCF8523: Ultra-low Power RTC with I2C Interface
The PCF8523 is a CMOS Real-Time Clock (RTC) and calendar optimized for low power consumption. Data is transferred serially via an I2C-bus with a maximum data rate of 1000 kbit/s. Alarm and timer functions are available with the possibility to generate a wake-up signal on an interrupt pin. An offset register allows fine-tuning of the clock. The PCF8523 has a backup battery switch-over circuit, which detects power failures and automatically switches to the battery supply when a power failure occurs.
PCF2123: Ultra-low Power RTC with SPI Interface
The PCF2123 is a CMOS Real-Time Clock (RTC) and calendar optimized for low power applications. Data is transferred serially via a Serial Peripheral Interface (SPI-bus) with a maximum data rate of 6.25 Mbit/s. An alarm and timer function is also available providing the possibility to generate a wake-up signal on an interrupt pin. An offset register allows fine tuning of the clock.
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