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TMS570LS3137: tC2TDELAY exceeds DS max value

Part Number: TMS570LS3137

Hi experts,

My customer is testing the time of the SPI Master TC2TDELAY.

The time of TC2TDELAY is as follows of DS.(CSHOLD = 0, CLOCK PHASE = 0, clock polarity = 0)

The formula for calculating the MAX value is as follows.

(C2Tdelay+2)*tc(vclk)-Tf(spc)m+Tr(spc)m+5.5

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 TC2TDELAY using this parameter the following:

=(C2Tdelay+2)*tc(vclk)-Tf(spc)m+Tr(spc)m+5.5

=(8+2)*11.11 - 2.5 + 2.5n + 5.5

= 116.61ns

However, when the customer measures this waveform on the customer's original board, this value is 120.7ns.

In other words, it exceeds the maximum value of DS.

Do you know why this value exceeds the maximum value for DS?

Other than this parameter, it is within the range of the maximum value, so the waveform is correct except for this parameter.

Best regards,
Sasaki