M5-128SLASH192-5VC datasheet(9/47 Pages) LATTICE

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MACH 5 Family

MACH 5 TIMING MODEL

The primary focus of the MACH 5 timing model is to accurately represent the timing in a MACH 5

device, and at the same time, be easy to understand. This model accurately describes all

combinatorial and registered paths through the device, making a distinction between

internal

feedback and external feedback. A signal uses internal feedback when it is fed back into the switch

matrix or block without having to go through the output buffer. The input register speciﬁcations

are also reported as internal feedback. When a signal is fed back into the switch matrix after having

gone through the output buffer, it is using external feedback.

The parameter, tBUF, is deﬁned as the time it takes to go through the output buffer to the I/O pad.

If a signal goes to the internal feedback rather than to the I/O pad, the parameter designator is

followed by an “i”. By adding tBUF to this internal parameter, the external parameter is derived.

For example, tPD = tPDi + tBUF. A diagram representing the modularized MACH 5 timing model is

shown in Figure 7. Refer to the Technical Note entitled MACH 5 Timing and High Speed Design

for a more detailed discussion about the timing parameters.

INPUT REG/

INPUT LATCH

tSIR (S/A)

tHIR (S/A)

tSIL

tHIL

tSRR

tCES

tCEH

tCO (S/A) i

tPDILi

tGOAi

tSRi

tBLK

tSEG

(External Feedback)

(Internal Feedback)

tS (S/A)

tH (S/A)

tSAL

tHAL

tSRR

tCES

tCEH

tPDi

tCO (S/A) i

tPDLi

tGOAi

tSRi

COMB/DFF/

LATCH

tPL1

tPL2

tPL3

OUT

tPT

tEA

tER

tBUF

tSLW

PIN CLK

20446G-014

Figure 7. MACH 5 Timing Model

M5-128/192-5VC Datasheet(PDF) 9 Page - Lattice Semiconductor

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