Serial real-time clock calibration

ST launched the world's first factory calibration of serial real-time clock (RTC) chips, due to omitted time-consuming calibration step, the use of these products, customers can simplify the assembly and testing operations. New Real-Time Clock M41T83 and M41T93 crystal package using built-in advance about the calibration accuracy of 5ppm, clock and date for the user equipment has brought new precision timing. Using a one-time programmable (OTP) register, ST can be tested in the factory during the fine-tuning on-chip 32.768 kHz oscillator internal load capacitance to ensure that these products a month time accuracy within 12 seconds. In addition to serial interfaces, these two new products share the same standards. M41T83 includes a 400 kHz I2C interface, while the M41T93 using 10 MHz SPI bus interface, is the world's first to run at speeds up to 10 MHz of real-time clock chip. These two new products, the first time introduced a series of advanced features, including analog calibration, a programmable auto-reload counter / timer and two alarms. In addition to the factory-programmed register, this product has also added a two analog calibration register, the user can reach through the register before the factory calibration settings. This feature is beneficial to adjust the ambient temperature because of errors caused by stray capacitance on the board or amend the accuracy of the impact of the time. Crystal-free QFN16 packages, the applications also need to register the new. Oscillator adjustment immediately in the test signal output to provide users with real-time Feedback adjustment. Auto-reload counter / timer with four user-selectable clock source of a complementary work to generate timing waveforms and provide periodic interrupt signal processors. Two programmable alarm pin through the two independent output signals in order to meet the needs of multiple applications to remind time. Both products include an on-board precision voltage reference tubes, automatically switch to standby power circuit a precise definition of the threshold pressure. This two-chip back-up supply current as low as 450nA (typical value), especially suitable for back-up power supply for capacitor applications, as well as the battery as a standby power products, in addition, as a result of the use of low-power manufacturing process, the minimum under 1.8V able to ensure precise timing. Built-in battery back-up monitor power supply voltage is responsible for inspection, when the need to replace the battery signal when prompted. Other features include 12 bytes of NVRAM and an oscillator failure detection circuit. If the oscillator pulse signals the loss of more than 3, oscillator failure detection circuit will be prompted to set up a bit to back-up power supply voltage may be too low, which may affect the accuracy of the time. In a back-up power supply for the capacitor applications, under-voltage during the regular session happen. Chip also integrates a programmable square-wave signal generator and a watchdog. When the supply voltage VCC disconnected, the chip will automatically transfer back-up power, to generate a 200ms power is restored after the reset signal exists. The power-on reset / low voltage detection for design engineers to save an independent board reset IC. Switching threshold voltage reset circuit and there are three voltage values (nominal 2.93V, 2.63V and 2.32V), when ordering products are clearly defined model. In addition to pre-calibration of the package outside the built-in crystal oscillator, M41T83 and M41T93 also using ST's low-cost space-saving 4mm x 4mm QFN16 package, and supporting the use of an external crystal oscillator. For the needs of mid-level real-time clock function of the low-end products and want the application of low cost, M41T83 product M41T82 Jane is a very good low-cost solutions. The product removed from the watchdog, square-wave signal generator and alarm reminder features, but retains the 400kHz I2C bus interface, analog user calibration, high precision voltage reference power control switch, battery monitor, 12 bytes of NVRAM and the reset output, a very small chip footprint low-cost 8-pin SOIC package.