Talk:Practical Electronics/Plugins/1Hz Oscillator

Suggestion: DS3231
I have a design that is more stable and have fewer parts, although requires a custom board and SMD soldering. The core parts are Maxim DS3231 DTCXO/RTC chip and a lithium coin cell (e.g. CR2032).

The DS3231 is a DTCXO based I2C RTC with square wave output and built-in crystal. A DTCXO is extremely accurate: 2ppm drift per year, or 1 minute per year. Compare common crystal oscillators with 15ppm or have a drift of 15 minutes a year.

The board will include a V+ input connected to an AMS1117-3.3 regulator to provide the DS3231 chip its required 3.3V supply voltage, the DTCXO itself with its SQW and 32kHz output pins exposed with level shifting using 2 MOSFETs and a interface to allow a microcontroller to talk to this chip over I2C.

After the board is assembled it should be attached to a microcontroller to set its internal calendar and enable its 1Hz output on SQW pin. A microcontroller can also be attached to keep this DS3231 chip in sync with a more accurate time source, like a GPS receiver.

Xcvista (discuss • contribs) 07:02, 29 December 2014 (UTC)