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Microchip offers stand-alone, real-time clock/calendar family

11/9/2010 06:12 AM EST
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powerlifter
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re: Microchip offers stand-alone, real-time clock/calendar family
powerlifter   11/10/2010 11:08:50 PM
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This device can operate from a crystal or external clock source, but in battery backup mode only the crystal would be operational. If you really need to reduce the number of crystals, you could also use the 32.768 KHz clock output in the RTCC as a second clock source. When considering this option, make sure your system requirements do not require an alarm output from the RTCC. -Alex Martinez, Product Marketing Manager, Microchip Technology Inc.

Jagdish Bisawa
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re: Microchip offers stand-alone, real-time clock/calendar family
Jagdish Bisawa   11/10/2010 6:04:23 AM
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Alex, that might not be a good idea, again, due to slight drifts in the external clock that is derived from a microcontroller. Such a solution might lead to inaccuracies in real-time estimation that can accumulated over a period of time. Also, what would happen if the device has to switched to a low power/battery mode ?

t.alex
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re: Microchip offers stand-alone, real-time clock/calendar family
t.alex   11/10/2010 5:39:12 AM
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Yep, it is quite true using internal oscillator is a bad idea due to huge drifting. Btw, for the IC above, is it possible to supply a clock source instead of fixed 32768 crystal? It is good if we can reuse some output clock from a microcontroller instead of maintaining 2 crystals on the board.

powerlifter
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re: Microchip offers stand-alone, real-time clock/calendar family
powerlifter   11/9/2010 9:14:10 PM
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Integrated crystals in real-time clocks often drift in frequency, when exposed to the high reflow-soldering temperatures. For this reason, many designers prefer to utilize external crystals and capacitors. If, however, designers prefer an integrated crystal and require higher accuracy, there are real-time clocks with an integrated hardware-compensation circuit to keep the clock calibrated across a wide temperature range. Since these crystal-integrated RTCs with compensation circuits are much more expensive—on average, about 4x the price of Microchip’s RTC— the system requirements usually dictate this selection. -Alex Martinez, Product Marketing Manager, Microchip Technology Inc.

t.alex
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re: Microchip offers stand-alone, real-time clock/calendar family
t.alex   11/9/2010 7:57:06 AM
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cool device. Just have a thought .. isn't nicer if the 32.768Khz crystal can be integrated into the IC?

Rick DeMeis
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re: Microchip offers stand-alone, real-time clock/calendar family
Rick DeMeis   11/9/2010 6:47:02 AM
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I was pre-briefed on these at ESC Boston. What's impressive are the features for the price, along with temperature compensation in software over the industrial temperature range.

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