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S/UNI-QUAD
PMC-Sierra, Inc.
PM5349 S/UNI-QUAD
DATASHEET
PMC-971239 ISSUE 6 SATURN USER NETWORK INTERFACE (155-QUAD)
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
18
Pin Name Type Pin
No.
Function
TCA Output J23 UTOPIA Transmit multi-PHY Cell Available (TCA)
The TCA signal indicates when a cell is available in
the transmit FIFO for the port polled by TADR[4:0]
when TENB is asserted. When high, TCA indicates
that the corresponding transmit FIFO is not full and
a complete cell may be written. When TCA goes
low, it can be configured to indicate either that the
corresponding transmit FIFO is near full or that the
corresponding transmit FIFO is full. TCA will
transition low on the rising edge of TFCLK after the
Payload word 19 (TCALEVEL0=0) or 23
(TCALEVEL0=1) is sampled if the PHY being polled
is the same as the PHY in use. To reduce FIFO
latency, the FIFO depth at which TCA indicates "full"
can be set to one, two, three or four cells. Note that
regardless of what fill level TCA is set to indicate
"full" at, the transmit cell processor can store 4
complete cells.
TCA is tri-stated when either the null-PHY address
(0x1F) or an address not matching the address
space set by PHY_ADR[2:0] is latched from the
TADR[4:0] inputs when TENB is high.
TCA is updated on the rising edge of TFCLK.
TFCLK Input K20 UTOPIA Transmit FIFO Write Clock (TFCLK).
This signal is used to write ATM cells to the four cell
transmit FIFOs.
TFCLK cycles at a 50 MHz or lower instantaneous
rate.