nected to the backplane ground). If the external ground floats considerably during transients, precautionary steps should be taken to prevent QGND from moving with

reference to the backplane ground. The receiver threshold should have the same ground reference as the signal coming from the backplane. A voltage offset between

their grounds will degrade the noise margin.

CD

T/R

LE

RBYP

ACK

An

Bn

HX

X

X

X

Z

H

LH

X

H

X

L

H

LH

X

H

X

H

L

LH

X

L

X

X

Bn

0

L

H

X

L

L-H

H

L

L

H

X

L

L-H

L

H

LL

H

X

X

H

L

LL

H

X

X

L

H

LLL

X

X

An

0

X

X = High or low logic state

Z = High impedance state

L = Low state

H = High state

L-H = Low to high transition

BTL = high and low state are nominally 2.1V and 1.0V, respectively.

TTL = high and low state are nominally 2.4V and 0.5V, respectively.

Package Thermal Characteristics

Linear Feet per

θ

Minute Air

44-Pin

44-Pin

Flow (LFPM)

PQFP

PLCC

082

45

225

68

35

500

60

30

900

53

26

Note 13: The above values are typical values and are different from the Absolute Maximum Rating values, which include guardbands.

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