Refer to chapter 14 of the rabbit 2000 microprocessors users manual for. Their different package sizes provide the customers more choices for time management. Overloading the crystal driver may cause the or to not start, or it mayoscillat be affected stopped temporarily e. If crystal unit is unavoidably heated, heat the lead part at 300. For parallel resonant circuits, the phase shiftload capacitors provide the.
The working principle is the same as of a tuning fork, the two tips will vibrate with a certain frequency. Tuning fork quartz crystal is used as a clock source in. Load capacitors the load capacitors c d and cg are regarded in series. Msp430 32khz crystal oscillators texas instruments. F page 4 of 4 packaging tape and reel tape drawing. Tuning fork crystal smdversion model kx 327nhf frequency 32. Cx4v tuning fork crystal 30 khz to 250 khz surface mount quartz crystal a b f d d top bottom c e package dimensions suggested land pattern c0 1 l1 c1 r1 2 r motional resistance l motional inductance c motional capacitance c shunt capacitance 11 10 d i mterm i nato ypc al x u inches mm inches mm a 0. Tuning fork crystal unit plastic package rohs compliant. Figure 4 shows c l as a capacitance in parallel with the crystal. For this circuit, then, im going to use 18pf capacitors for c1 and c2.
The frequency is defined by the mass of the tips and. Piercegate crystal oscillator, an introduction crystek. Figure 5 shows a typical curve of frequency vs load capacitance. Smd tuning fork crystal resonators khz band crystal resonators.
Ceramic package rohs compliant pb free cm1610h 5,000pcsreel. Many tuning fork crystals require much lower loading capacitance than atcut hf crystals. Psocbased embedded design and quartz tuning fork for low. Complete cts part number, frequency value, date code and manufacturing site code information must appear. Plastic package rohs compliant cm200c 3,000pcsreel features frequency range. The cc8vt1a is a low frequency smt quartz crystal unit that incorporates a tuning fork quartz crystal resonator. Due to the ulp design and external environmental conditions like crystal esr, load capacitance, shunt capacitance, humidity, pcb contamination, and temperature, the startup behavior of the.
The load capacitance presented to the crystal in a piercegate oscillator is, eq. Load tolerance page 1 of 1 features parameters conditions series. For example, a crystal intended for a 6 pf load has its specified parallel resonant frequency when a 6. Quartz crystal has been also called the water spirit since early times. Tuning fork flexure mode operating principle the name tuning fork comes from the design of the crystal plate called crystal wafer or blank being similar to the shape of a tuning fork.
Load capacitance c l smt package tuning fork package size frequency f l frequency tolerance temperature range qualification 6. Ecs frequency abbreviation load capacitance package custom options tolerance packaging pad connections 1 inout 2 outin the miniature ecx31b is the most cost effective smd tuning fork crystal today. Due to the ulp design and external environmental conditions like crystal esr, load capacitance, shunt capacitance, humidity, pcb contamination, and temperature, the startup behavior of the whole circuit might be different. When doing measurements on crystals, the crystal should be placed as. Crystal considerations with maxim realtime clocks rtcs. Tuning fork crystal kt15, kt26, kt38 fox electronics. Load capacitance measurement for crystal oscillator. This frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters. Device quantity is 3k pieces maximum per 180mm reel. Selecting and testing 32khz crystal oscillators for atmel avr microcontrollers features. The load capacitance cl is the capacitive load of the oscillating circuit as seen from the pins of the crystal. Low frequency reflowable tuning fork crystal moisture sensitivity level msl level 1 ab26trq 32 68 freq. Application note 58 crystal considerations for dallas real.
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a precise frequency. It operates under vacuum in a hermetically sealed ceramic package with metal lid. Choosing the load capacitors, then, looks like this. Taitiens tuningforktype crystals have low power consumption ideal for portable application. Selecting and testing 32 khz crystal oscillators for. In this way, quartz crystal is used for quartz crystal products in diverse ways in our daily life.
Load capacitance c l au flashed pads smt package tuning fork package size frequency f l frequency tolerance temperature range qualification 4. The linked datasheet shows loading capacitances of 7, 9 or 12. To determine the total effective load capacitance, the board layout stray parasitic capacitance has to be. Ecx306 smd tuning fork crystal the ecx306 is a compact smd tuning fork crystal. The load capacitance is defined as the effective capacitance, external to the crystal package, appearing between the crystals terminals. Figure 4 shows cl as a capacitance in parallel with the crystal. Negative resistance measurement for crystal oscillator. The load capacitors used in an oscillator circuit, cl1 and cl2, plus any stray capacitance. Choosing crystal load capacitors is neither art nor science. Taitiens tuningfork type crystals have low power consumption ideal for portable application. Their different package sizes provide the customers more choices for time.
Tuning fork crystal unit ceramic package rohs compliant pb. Capacitors cd and cg are the load capacitors and resistor rd is the dumping resistor. Like an oldschool bell, hit it just right to get the right frequency. Tuning fork crystal 2pads tuning fork 4115 smd ceramic package package dimensions 4. The load capacitance c l is the capacitive load of the oscillating circuit as seen from the pins of the crystal.
These are the two most common load capacitance values in the crystal industry. Crystal load capacitors calculation all about circuits. All maxim rtcs have integrated c l 1 and c l 2 capacitors. Tuning fork crystals, or also known as wrist watch crystals, are one of the oldest crystal design used for time. Cts releases new series of tuning fork crystal models cts. Ecx 306 template frequency control, crystal, oscillator. Fundamentals of crystal oscillator design electronic design.
Tuning fork crystal smdversion model kx 327lt frequency 32. Not included in the pn if the tolerance has the standard value 20ppm example. The load capacitors used in an oscillator circuit, c l 1 and c l 2, plus any stray capacitance in the circuit, combine to create the overall load capacitance. Frequency deviation of a tuningfork crystal over temperature. Standard vs tuning fork crystals all about circuits. Also, quartz crystal has been highly valued for its transparency, hardness and so on. This article describes a commercial quartz tuning fork qtf, 8 mm in height by 3 mm in diameter, holding a twoterminal electronic component with a nominal frequency of 32.
Kn product family surface mount tuning fork crystal 2. Crystal manufacturers normally cut and trim their crystals to have a specified resonant frequency with a known load capacitance added to the crystal. Each discrete loading cap should be twice the required value, minus the capacitance of the oscillator pin and stray capacitance. The load capacitors used in an oscillator circuit, cl1 and cl2, plus any stray capacitance in the circuit, combine to create the overall load capacitance. The 32khz crystal oscillator driver of avr microcontrollers is optimized for very low power consumption and thus the crystal driver strength, is limited. Ceramic package rohs compliant pb free cm1610h 5,000pcsreel features ultralightweight microminiature tf crystal units smd type frequency range. Selecting and testing 32 khz crystal oscillators for avr. The crystal ive chosen for my circuit requires a load capacitance of 12.
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