PMC-Sierra PM5349 manual Tca, Tfclk

		PMC-Sierra, Inc.	PM5349 S/UNI-QUAD
S/UNI-QUAD
DATASHEET
PMC-971239	ISSUE 6		SATURN USER NETWORK INTERFACE (155-QUAD)

Pin Name	Type	Pin	Function
		No.
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.

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use 18