Easily differentiate passive and active crystals in the simplest way

Crystal oscillator from the material can be divided into quartz crystal oscillator and ceramic crystal two categories, and from the properties of crystal oscillator can be divided into passive crystal and active crystal oscillator. Quartz crystal and ceramic crystal vibration from the appearance of very advantageous to distinguish, after all, is also two completely different materials. and the passive crystal and active crystal sometimes silly people are not clear. Especially for 2520 SMD Crystal, 3225 SMD Crystal, 5032 SMD Crystal and for four feet of quartz crystal oscillator, both the existence of passive crystal, there are active crystal oscillator, only from the appearance of We are very distinguished. So today, Rite-Hite Electronics is carefully collated about how to correctly identify passive crystal and active crystal oscillator.
Passive crystal is also called the resonator, the crystal pin position is usually 2 feet and 4 feet, the passive crystal in the circuit need to rely on the external circuit to start the vibration, itself can not be vibration. Passive crystal has a plug-in shape also has a patch shape, such as we often see the 32.768KHZ cylindrical crystal, or 49/s crystal package, 49/u Crystal package, ceramic two feet, three-pin plug-in package; SMD Crystal oscillator in the more common such as 3215 SMD Crystal Package Series, or 3225 SMD Crystal two foot four-pin package.

The active crystal is also called the oscillator, and the difference between the passive crystal oscillator is that the active crystal itself can be shaken, without the use of external circuitry, because of its own structure inside the oscillator. The active crystal is composed of quartz crystal and oscillating film. The active crystal oscillator does not need the internal oscillator of the DSP, the signal quality is good, more stable, and the connection method is relatively simple, do not need complex configuration circuit. However, such high-end active Crystal has its own shortcomings, compared with passive crystal oscillator, the active crystal signal level is fixed, need to choose the right output level, flexibility is poor, and high prices. More than four feet including four-pin SMD crystal oscillator are active crystal, here, with the definition of passive crystal, 2 feet crystal and 4 feet are passive crystal mutual repetition. So what we need to figure out is whether the four-pin SMD crystal is a passive crystal or active crystal, and we will discuss it with you today.

Active Crystal front is usually a bit of a marker, most of the active Crystal Point will be located in the lower left, the point is in the position of foot 1, the counter-clockwise foot is 2,3,4. Active Crystal pin position is: 1 feet floating, 2 feet grounding, 3 feet output, 4 feet voltage. There is no dot mark on the surface of the passive crystal oscillator.
Passive crystal has a plug-in package and SMD packaging, active crystal is no exception, but the active Crystal plug-in package is more square.

Square Active oscillator pin distribution:
1, square, using the DIP-8 package, the dot is 1 feet. 1-NC, 4-gnd, 5-output, 8-VCC
2, rectangular, using the DIP-14 package, the dot is 1 feet. 1-NC, 7-gnd, 8-output, 14-VCC
BTW:
1, the power supply has two kinds, one is TTL, can only use 5V, one is HC, can 3.3v/5v
2, the edge has a sharp angle, three rounded corners, sharp angle is a foot, and the alignment.
VCC out
NC (point) GND

The active crystal is a square or rectangular metal box, looking at the nominal side (top), left bottom empty foot, right down, upper left VCC (5V), right upper output. Connect the power supply to see the waveform with an oscilloscope.

Active Crystal is not just a simple oscillator, the active crystal can also be subdivided into quartz oscillator, temperature-compensation oscillator, voltage-controlled oscillator, voltage-controlled temperature-compensation oscillator. Four types of oscillators have different uses in the circuit. Quartz oscillator is a common oscillation function, the temperature compensation oscillator is the name of the temperature compensated, when the temperature fluctuations affect the frequency stability, the temperature compensation oscillator will automatically be temperature compensated; the voltage-controlled oscillator is the name of the pressure control, when the crystal voltage is found to be unstable, voltage control oscillator can be controlled, Let the voltage return to normal state, and the pressure-controlled temperature-compensation oscillator is the function of both.
This is the difference between active crystal and passive crystal, whether or not you have solved a big doubt in your heart.