通过下面两幅图进行分析：

图1 数据输入FPGA模型

图2input delay max/min 公式

1.对input delay max的理解：

按图1，可以得出下面公式：

data arrival time = launch edge + Tclk1(max)+Tco(max)+(Tdata_PCB(max)+Tcl)

+Tdatain(式1-1)

data required time = latch edge + Tclk2ext(min) + Tclk2int – Tsu(式1-2)

slack = data required time - data arrival time

= latch edge + Tclk2ext(min) + Tclk2int – Tsu –[launch edge + Tclk1(max)+

Tco(max)+(Tdata_PCB(max)+Tcl) +Tdatain]

=( latch edge–launch edge) +( Tclk2int – Tsu–Tdatain) –

(Tclk1(max)+ Tco(max)+(Tdata_PCB(max)+Tcl) –Tclk2ext(min)) (式1-3)

按照图2的公式：

data arrival time = launch edge + input delay max + Tdatain (式1-4)

data required time = latch edge + Tclk2int – Tsu (式1-5)

slack = data required time - data arrival time

= latch edge + Tclk2int – Tsu

–[launch edge + input delay max + Tdatain]

= ( latch edge–launch edge) + (Tclk2int – Tsu–Tdatain ) –

input delay max (式1-6)

比较（式1-3）和（式1-6）可以得出(式1-7)：

input delay max = Tclk1(max)+ Tco(max)+(Tdata_PCB(max)+Tcl) –Tclk2ext(min)

= (Tdata_PCB(max)+Tcl) –(Tclk2ext(min) –Tclk1(max))+ Tco(max)

(式1-7)

(式1-7)就是图2中给出的input delay max公式。

2.对input delay min的理解：

按图1，可以得出下面公式：

data arrival time = launch edge + Tclk1(min)+Tco(min)+(Tdata_PCB(min)+Tcl)

+Tdatain(式2-1)

data required time = latch edge + Tclk2ext(max) + Tclk2int +Th (式2-2)

slack = data arrival time– data required time

= [launch edge + Tclk1(min)+Tco(min)+(Tdata_PCB(min)+Tcl) +Tdatain]

–[latch edge + Tclk2ext(max) + Tclk2int +Th]

=( launch edge–latch edge)+( Tdatain–Tclk2int–Th) +

Tclk1(min)+Tco(min)+(Tdata_PCB(min)+Tcl) –Tclk2ext(max) (式2-3)

按照图2的公式：

data arrival time = launch edge+ input delay min + Tdatain (式2-4)

data required time = latch edge + Tclk2int +Th (式2-5)

slack = data arrival time – data required time

=[launch edge+ input delay min + Tdatain]–

[ latch edge + Tclk2int +Th]

=( launch edge –latch edge)+( Tdatain–Tclk2int–Th)+

input delay min (式2-6)

比较（式2-3）和（式2-6）可以得出(式2-7)：

input delay min = Tclk1(min)+Tco(min)+(Tdata_PCB(min)+Tcl) –Tclk2ext(max)

=(Tdata_PCB(min)+Tcl) –(Tclk2ext(max) –Tclk1(min))

+ Tco(min) (式2-7)

(式2-7)就是图2中给出的input delay min公式。