Hi experts,
My customer is testing the time of the SPI Slave Td(scsl-senal)s.
The time of Td(scsl-senal)s is as follows of DS.(CSHOLD = 0, CLOCK PHASE = 0, clock polarity = 0)
The formula for calculating the MAX value is as follows.
tc(VCLK) + tf(ENAn) + 27
The customer parameters are as follows.
| Parameter | Item | Parameter | unit |
| f(vclk) | 90 | MHz | |
| tc(vclk) | 11.11111111 | ns | |
| Tc(spc)m [clock] |
66.592 (SPICLK = 15MHz) | ns | |
| Tr(spc)m[clock] | 2.5 | ns | |
| Tf(spc)m[clock] | 2.5 | ns | |
| Tr(spics)m[cs] | 2.5 | ns | |
| Tf(spics)m[cs] | 2.5 | ns | |
| Tr(miso)m[miso] | 2.5 | ns | |
| Tr(enan)s[ena] | 17.40 | ns | |
| Tf(enan)s[ena] | 3.72 | ns | |
| C2Tdelay | 8 | - | |
| T2Cdelay | 8 |
- |
Calculating Td(scsl-senal)s using this parameter the following:
=tc(VCLK) + tf(ENAn) + 27
=11.11ns + 3.72ns + 27
= 41.83ns
However, when the customer measures this waveform on the customer's original board, this value is 87.56ns.
In other words, it exceeds the maximum value of DS.
Do you know why this value exceeds the maximum value for DS?
Best regards,
Sasaki
