Tool/software:
Questions:
(1) What is the accuracy of the DPLL inside the DSP? Is it about 1700ppm?
Please provide the accuracy of the DPLL.
(2) Is it possible that CLKOUT fluctuates due to an internal defect in the DSP?
(3) What is the cause of CLKOUT fluctuation?
Usage:
(1) I am using TMS320VC5507PGE.
(2) I input 16.384MHz (±10ppm) from an external oscillator to DSP pin 13.
(3) The clock is multiplied by 12 inside the DSP to operate at 196.608MHz.
(Register settings: PLL MULTI=24, PLL DIV=1)
(4) I output 16.384MHz, which is 1/6 of 196.608MHz, to CLKOUT (pin 15).
(5) The DSP power supply voltage is 1.62V.
Problems:
CLKOUT frequency: 16.384MHz, but fluctuates between 16.384MHz and 16.356MHz.
(1) When the ambient temperature is below 10°C or above 30°C, 16.384MHz is output.
(2) At around 25°C, it becomes 16.356MHz. (-0.17% [-1700ppm])
(3) At startup, it may gradually drop from 16.384MHz and settle to 16.356MHz in about 10 seconds.
Sensitive to temperature, it will return to 16.384MHz if the ambient temperature changes by a few degrees from the abnormal state.
(4) There is no soldering defect on the DSP pin.
(5) When abnormal, the external oscillator is stable at 16.384MHz. There is no problem with the waveform.
(6) The 1.6V power supply voltage is actually measured at 1.62V. (7) The noise of the 1.6V power supply is about 70 [mVp-p].
(8) When CLKDIV="000", CLKOUT: 196.328MHz. The normal value should be 196.608MHz.
(9) This occurs in 2 out of 5 DSPs.
