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Note: For spec numbers 001-00001 to 001-99999, the KBA number is five digits; for spec numbers 002-xxxxx, add '2' to make it a 6-digit number. For example, for spec 002-12345, the KBA number is 002-212345 to distinguish it from KBA12345 for spec 001-12345.
Question: How can we calculate the maximum operating junction temperature for clock devices?
Answer: Maximum Operating Junction temperature (this is the maximum junction temperature at which the thermal characteristics of the IC are guaranteed).
We can use the below formula to calculate the maximum operating junction temperature:
Tjmax = Theta Ja * Pd(max) + Ta (max)
Tj is the Junction Temperature
Theta Ja is the Junction to ambient thermal resistance
Ta = Ambient temperature = 85°C
Pd= Power dissipation = VDD * Itot
Total current, Itot = Idc + Iac
Idc value can be found in the datasheet
Iac = K*C*V*F
K = 1/2 for 50% duty cycle. You can modify this parameter accordingly.
C = Load Capacitance
V = VDD
F = Frequency
Then calculate total power by multiplying by VDD.
Please note this is the max operating junction temperature that the device will reach as per the application or as per the values you enter or select.
Some datasheet doesn’t show the current, IDC and IAC separately, it shows the Total current “Itot” at a specific frequency. For this case we recommend the linear interpolation by C, F and V because that will be the worst case.
For example in the CY27410 datasheet, IDDO for CMOS, specified 6.0mA(max) at 10-pF 33MHz, so if you use 66MHz, the IDDO will be 6*2=12mA for 66MHz operation, and so-on.
Phase noise will be higher in VCXO mode when compared to the non-VCXO mode in general. CY29430 is a 16 pin QFN device from Cypress which has crystal oscillator inside, while the CY5107 is a wafer offered from Cypress which can be incorporated into different applications with any packaging.
Do the following to improve phase noise when VCXO is enabled:
Do not apply any external voltage (VC is the voltage at the VCXO pin) VC = VDD/2 when the device is configured to operate in VCXO mode. Setting the VC at VDD/2 may cause spurs at the output phase noise. Apply a voltage that is outside the range of VDD/2 – 10 mV to VDD/2 + 10 mV.
For VCXO settings, add an LC filter circuit to ensure that a noise-free DC signal is applied at this input. The more the noise-free input, the less phase noise.
Question: What is the status of all I/Os of Ultra 37K CPLD during programming? Answer: All I/Os (except TDO) are tristated during device programmin...
Question: What is the status of all I/Os of Ultra 37K CPLD during programming?
All I/Os (except TDO) are tristated during device programming. This allows soldering the devices directly onto user board without having to erase them first. It allows the user to power-up a board and program the CPLD devices on it without worrying whether their initial, non-blank state will cause any problems such as output contention with other devices on the board.
Please be noted our entire Cypress CPLD product are Obsolete and not recommended for new design and development. For more information on CPLD product, please visit our webpage:http://www.cypress.com/go/cpld
Please be noted our entire Cypress CPLD product are Obsolete and not recommended for new design and development. For more information on CPLD product, please visit our webpage: http://www.cypress.com/go/cpld