Quartz crystals - terms / properties (41kB)

terms and definitions commonly used in oscillating quartz crystals

Oscillator circuits with transistors

layout suggestions for discrete transistors with oscillator circuits, a.o. NF-oscillator from 800 kHz, Pierce and Colpitts oscillator tone, Pierce-overtone oscillator to 200 MHz

Oscillator circuits with inverter IC

Quartz oscillator circuits for standard microprocessor Crystals in AT section 3-25 MHz using integrated, unbuffered inverters

Pierce oscillator circuit for tuning fork Crystals 10 - 600 kHz

tips to circuit design with tuning fork quartz crystals of the series V by the manufacturer Statek - these tips also apply in general to all tuning fork Crystals in Pierce oscillators

explanatory notes on the order code:
e.g.: Quartz 32,000000 MHz¹⁾ HC-49/US-2,4²⁾ 50/100/20/30³⁾ GT ⁴⁾ BT ⁵⁾ taped ⁶⁾

1) frequency with max. 6 decimals in MHz
2) case: 4,1 = height h = 4,1 mm (standard); optional h = 3,1 or 2,7 mm!
3) here are – separated with slashes – the following values defined: frequency tolerance (ppm or 10-6), max. allowed tolerance over operating temperature range, the operating temperature range and the load capacitance
30 ... ±30 ppm @ +25°C
100 ... ±100 ppm over operating temperature range
10 ... -10...+60°C; only lower temperature limit is mentioned, temperature tolerance is symmetric around +25°C or, in special cases, the lower and upper limit e.g. /-40+85/
30 ... load capacitance CL = 30 pF; S means series resistance (CL = ∞)
4) GT ... fundamental (default up to 30 MHz, fundamental is standard!) 3.OT ... means 3rd overtone
5) AT ... AT-cut (default under 30 MHz, AT is standard) BT ... BT-cut
6) option: e.g. gegurtet = tape on reel

Recommendation on quartz crystals in ceramic packages with 4 solder pads:

Quartz crystals in ceramic cases are available in sizes 3,2x5, 3,5x6 and 5x7mm with 2 and 4 solder pads. For new developments, we recommend that you use the versions with 4 solder pads: 2 pads of which are connected to the metallic lid and the quartz thus has an improved EMI performance.
While there is no product discontinuation for 2 pad housing but the availability of the 4 pad package is better, and we will focus on expanding our warehouse towards the 4 pad model.

Recommended Quartz specification for the RFID IC from TI TRF7960 and TRF7961:

frequency: 13.560000 MHz
fundamental mode, AT-cut, parallel resonance
frequency tolerance ±20 ppm max.
aging < 5 ppm/year
operating temperature range -40°C to 85°C
resonance resistance max. 50 Ohm

Informations come from data sheet SLOU186E August 2006 revised July 2008

Selection criteria of load capacity:

These clock crystals are offered with load capacities ranging from 6 - 12,5pF, the IC manufacturers generally write these values prior to the operation of the circuit guarantee. The following properties result from:
Settling with small CL small, with large CL high (0,5...3 seconds)
Stability at high CL better than at low.
Load (power consumption) increases with the CL value.