MHz surface mount crystal oscillator is currently the most widely used crystal oscillator product in the market. Compared with active crystal oscillators, surface mount crystal oscillators have better cost-effectiveness. Therefore, surface mount crystal oscillators are the most widely used and mainstream crystal oscillator products in the consumer electronics industry. This article takes you to understand the technical issues related to MHz surface mount crystal oscillators.
MHz surface mount crystal oscillator uses AT cutting to generate bulk acoustic resonance in thickness cutting vibration mode
The fundamental frequency is determined by the thickness of the chip
General specifications of surface mount crystal oscillator
1. Nominal Frequency: The required rated frequency
For example: 25MHz or 50MHz for Ethernet applications
2. Frequency Tolerance: The deviation between the actual frequency and the nominal frequency at an ambient temperature of 25 ℃
± 20ppm is the common maximum specification
3. Frequency Stability: Frequency deviation at operating temperature
± 20ppm is the common maximum specification
4. Load Capacity: The expected capacitive load seen by a crystal when providing rated frequency
A typical load capacitance CL value is between 6-20pF
5. ESR: Equivalent series resistance or dynamic resistance. The larger the value, the more difficult it is to start oscillation
80 Ω is the commonly used maximum specification for 2 × 1.6mm crystal oscillators
6. Drive Level - The power or oscillation output level required for the operation (driving) of crystal devices.
100 μ W is the common maximum specification
Common dimensions and trade-offs of MHz surface mount crystal oscillators
The MHz surface mount crystal oscillator adopts industry standard sizes ranging from 7.0 × 5.0mm to 1.0 × 0.8mm. However, the 7.0 × 5.0mm standard is gradually no longer becoming the mainstream size. Previously, there were 8.0 × 4.5mm sizes, and only a small number of old solutions are still in use. Other sizes are basically mainstream now, such as SMD 5032, SMD 3225, SMD 2520, SMD 2016, SMD 1612 and other sizes of surface mount crystal oscillators
Balancing the dimensions of crystal oscillator products
1). Larger crystal oscillator: lower ESR, higher maximum driving level, lower minimum frequency range
2). Smaller crystal oscillator: higher output, stricter process control, higher maximum frequency, longer product lifecycle
Frequency balance
The higher the frequency, the lower the ESR resistance
For large-scale projects, the industry's "dessert" is currently 2x1.6mm
Many projects with low output or pursuing cost-effectiveness are still using 3.2x2.5mm crystal oscillators
The above is a brief introduction to MHz surface mount crystal oscillators. We hope to discuss the industry development of crystal oscillator products and information on the crystal oscillator market with everyone, and make progress together!
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