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TFP401, TFP401A

SLDS120G – MARCH 2000 – REVISED MAY 2016

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10.2.2 Detailed Design Procedure

10.2.2.1 Data and Control Signals

The trace length of data and control signals out of the receiver should be kept as close to equal as possible.

Trace separation should be ~5X Height. As a general rule, traces also should be less than 2.8 inches if possible

(longer traces can be acceptable).

Delay = 85 × SQRT ER

where

•

ER = 4.35

•

Relative permittivity of 50% resin FR-4 @ 1 GHz

•

Delay = 177 pS/inch

(1)

Length of rising edge = TR(picoseconds) ÷ Delay

where

•

TR = 3 nS

•

= 3000 ps ÷ 177 ps per inch

•

= 16.9 inches

(2)

Length of rising edge ÷ 6 = Max length of trace for lumped circuit

where

•

16.9 ÷ 6 = 2.8 inches

(3)

Figure 19. Data and Control Signals Design