The SiT5008 from SiTime goes to 60 MHz, draws 3.5 mA, and features a standby mode.
Battery-powered devices with or without wireless connectivity can always benefit from longer battery life. Every component that uses power drains batteries, and that include oscillators. The SiT5008 temperature-compensated silicon MEMS oscillator (TCXO)draws just 3.5 mA (typical) while providing clock frequencies from 1 MHz to 60 MHz, programmed at the factory based on ordered part number. Output frequencies are specified as accurate to within six decimal places. The has three operating voltages (1.8 V, 2.8 V, 3.3 V) that you specify at time of ordering. Frequency stability is ±2 ppm to ±10 ppm.
In addition to specifying operating voltage and frequency, you must specify output drive and a control pin’s function. An oscillator’s signal rise and fall times present a design tradeoff between jitter and EMI because of the harmonics in signal edges. Slower edges reduce emissions while faster edges reduce jitter. In addition to specifying output frequency and operating voltage, you must specify the device’s drive strength based on the desired rise time, power-supply voltage, and capacitive load. The plot below shows the harmonic amplitude as a function of harmonic number for several rise times.
Harmonic energy drops with higher harmonics.
The SiT5008 has an OE/ST/NC control pin where you specify that pin’s function when ordering. As an output enable, you control the SiT5008’s output (active or high-Z) but the device remains active. If configured as a standby pin, the control pin puts the device in a sleep mode. You can also specify the pin to have no function.
Filed Under: Uncategorized