Compact dual oscillator and power on reset for MCU

Would you consider connecting an IC with a dual-speed oscillator and a power-on reset to your MCU? This is what MAX7378 does. This is a good replacement for ceramic resonators, crystals, and other oscillator modules, and discrete reset circuits. The good thing here is that at any time, you can select either low-frequency 32.768kHz or a high frequency from range 600kHz to 10MHz.The clock frequency can be switched at any time without glitches.


MAX7378 can be powered from 2,7V to 5,5V, so it is suitable for most MCU types. Comparing to Crystal resonators, it is resistive to vibrations and EMI. It is a good solution for the automotive and industrial environment. High-frequency oscillator error reaches ±2% at 25°C at 5V power supply. In other words, speaking oscillator frequency stability is about ±325ppm (when crystal stability is from ±10ppm to ±100ppm). So it doesn’t correspond to crystal accuracy, but it suits most non-time-critical applications. 32.768kHz oscillator is more accurate with an error of 1%, but it still a bit much for time measurements.

Reset circuitry takes care that reset will occur after 100us after clock startup. Reset output is available in three different options: two of them are push-pull types (active LOW or active HIGH), and the third one is open drain and requires an external pull-up resistor (dashed in the picture below).

The reset signal becomes active if the voltage drops below the threshold. IC is coated in the small 8-pin package and has dimensions of only 3,05×5,03mm, including pins.

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