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Low frequency clock chip supports long-duration timing

Linear Technology has announced the LTC6991, a low-frequency clock specifically designed for long duration timing applications. The chip is the part in the TimerBlox family of silicon timing devices, in which a programmable oscillator is combined with circuitry and logic. A programmable frequency range allows the clock to operate with a period from 1ms to 9.5 hours. The company claims that this makes the chip useful for intervalometers, watchdog timers and periodic wake-up timers with minimal components and effort. The chip is programmed using 1 to 3 resistors with a maximum frequency error that is claimed by the company to be less than 1.5%. The chip offers, first cycle start-up within 500us of power, and a reset function is available to truncate the output pulse and hold the output in a high or low state. The polarity of the reset input and the output signal can be configured for active-low or active-high operation. The output frequency of the chip can be dynamically controlled via a separate control voltage.

TimerBlox devices are solid state and can be operated under high acceleration, vibration and temperature extremes. No timing capacitors, no crystals, no microcontroller and no programming are required, according to the company. The 20mA ‘source and sink’ capability enables direct driving of opto-isolators for electrical isolation. Specified over the temperature range of -40 to 125°C, the TimerBlox parts are suitable for demanding automotive and industrial environments. The SOT23 footprint allows each timing device to be placed at the point of use, without routing signals over long distances, providing a suitable timer for space-limited applications such as handheld and portable devices.