Most popular common questions about built-in cryst

2022-08-14
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Common questions about built-in crystal packaging

summary: when choosing an independent real-time clock (RTC), Maxim can now provide a package with integrated quartz crystal for you to choose from. This new package integrates a serial interface (I C, 3-wire or SPI) RTC device and a matching 32.768KHz quartz crystal into a single 16 pin so package

the following questions are often asked about this new package integrated with quartz crystal in use:

which real-time clocks can provide this package

devices that provide this packaging option include ds1337, ds1338, ds1339, ds1340, ds1374, ds3231, ds3232, ds3234, and ds32x35. More devices will be offered in this package in the future

the device model with this package has the suffix 'C'. For example, ds1337c represents ds1337 in an integrated crystal package. Ds3231, ds3232, ds3234 and ds32x35 are not named according to this naming convention because the device has only a built-in crystal package. Therefore, there is no need to encapsulate the indicator

maxim's other devices use this package

this so package with integrated crystals provides a new packaging option for ds32khz 32.768KHz temperature compensated crystal oscillator (TCXO)

how about the package size

this package is a standard 300mil wide, 16 pin or 20 pin so package. For 16 pin package, the size is 400mil x 300mil x 100mil; For 20 pin packages, the size is 500mil x 300mil x 100mil. Downloadable technology package

what are the benefits of the new packaging options

ensure that RTC and crystal work well (appropriate load capacitance and ESR)

eliminate the problem of crystal procurement

immediately organize tracking and verification without finding it. It is necessary to consider the problem of crystal layout (PCB) if the processing cycle is too long

will not add additional production steps like through-hole crystals

will the timing accuracy be improved

because the leakage caused by parasitic capacitance and impurities on PCB is reduced, and improper crystal load capacitance is avoided, the timing accuracy is improved. The data of the device gives the expected crystal accuracy at nominal VCC and room temperature (25 C)

does Dallas Semiconductor provide precision timing scheme

yes, ds3231 is a high-precision I C real-time clock, which integrates rtc/tcxo/crystal. It can provide 2ppm frequency accuracy in the range of 0 C to +40 C, and 3.5ppm accuracy in the range of -40 C to 0 C and +40 C to +85 C. Other devices, including ds3232, ds3234 and ds32x35, can also provide spring fatigue testing machine as a common equipment in industry for accurate timing

compared with discrete components, does this new packaging form increase the cost

the total solution cost of the built-in crystal package is the same as that of the discrete components (crystal and RTC)

are there any other special operation problems

this package contains a quartz crystal tuning fork crystal oscillator. Mounting equipment can be used, but care must be taken to avoid excessive impact. Ultrasonic cleaning should be avoided

moisture sensitive packaging is adopted in the factory. The operating instructions listed on the package label must be followed to prevent damage to the device during reflow soldering. Please refer to ipc/jedec j-std-020 standard for classification of moisture sensitive devices (MSD)

is there a PCB layout guide

unless there is a layer separation between the package and the signal line, it is recommended not to lay the signal line under the package. All NC (unconnected) pins must be grounded

are there any special requirements for reflow soldering of this package

rohs packages must be welded according to the reflow characteristic curve in accordance with JEDEC j-std-020 standard

how many reflow soldering times can this package withstand

twice (at most)

does the package meet RoHS or lead-free (Pb free) standards

the package has passed the certification and conforms to RoHS 5/6 standard. As a piezoelectric device, the package has lead-free exemption. For details, please refer to our lead-free information page. Device models with lead-free exemption are marked with # mark

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