PM73487 datasheet(77/251 Pages) PMC

77 / 251 page

PM73487 QRT

PMC-Sierra, Inc.

PMC-980618

Issue 3

622 Mbps ATM Traffic Management Device

Released

Datasheet

4.3.3

Switch Element Interface Signals

Table 10. Switch Element Interface Signals (47 Pins)

Signal Name

Ball

Type

Drive/

Input Level

Slew

Rate

Description

SE_CLK

AA26

CMOS

Switch Element Clock is the 50 MHz or

66 MHz clock for nibble transfer.

RX_CELL_START

W28

5 V or LV

TTL

Receive Cell Start indicates the SOC time in

the receive direction. It should be driven high

every cell time (118 SE_CLKs).

BP_ACK_IN(3:0)

R27, U29,

U28, T28

5 V or LV

TTL

Backpressure Input 3 down to 0. It carries the

cell acknowledge and backpressure from the

switch fabric.

SE_SOC_OUT

L27

Out

8 ma

Mod

Switch Fabric Start Of Cell Out indicates the

SOC for all four SE_D_OUT signals. This sig-

nal precedes the first nibble of cell by one

clock. For cells leaving the QRT and entering

the switch fabric, this signal indicates the SOC.

SE_D_OUT0(3:0)

P25, R28,

R25, R26

Out

5 ma

Mod

Switch Element Data Out Ports 3 down to 0

Bits 3 down to 0 are four nibble-wide pathways

that carry the cell to the QSEs (PM73488).

SE_D_OUT1(3:0)

N28, P28,

P26, P27

Out

5 ma

Mod

SE_D_OUT2(3:0)

N27, M26,

N29, M27

Out

5 ma

Mod

SE_D_OUT3(3:0)

L26, N26,

M28, L28

Out

5 ma

Mod

BP_ACK_OUT(3:0)

U27, T27,

U26, V28

Out

8 ma

Mod

Backpressure Output 3 down to 0 asserts mul-

tipriority backpressure and cell acknowledge

toward the switch fabric.

SE_SOC_IN(3:0)

V26, T25,

V25, U25

5 V or LV

TTL

Switch Fabric Start of Cell 3 to 0 indicates the

SOC time in the transmit direction for the four

incoming SE_D_IN3, SE_D_IN2, SE_D_IN1

and SE_D_IN0, respectively.

SE_D_IN0(3:0)

AB26, AA25,

AC28, AD28

5 V or LV

TTL

Switch Element Data In Ports 3 to 0 Bits 3

down to 0 are part of the nibble-wide, 50 MHz

data pathway that carries the cell from the

switch fabric.

SE_D_IN1(3:0)

AB27, Y26,

AD29, AB28

5 V or LV

TTL

SE_D_IN2(3:0)

W26, Y25,

Y27, W25

5 V or LV

TTL

SE_D_IN3(3:0)

W27, AA28,

AA27, Y28

5 V or LV

TTL

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