TXC-06312BIOG Transwitch Corporation, TXC-06312BIOG Datasheet - Page 48

• Manufacturer Part Number: TXC-06312BIOG
• Manufacturer: Transwitch Corporation

Specifications of TXC-06312BIOG

• Lead Free Status / Rohs Status: Supplier Unconfirmed

PRELIMINARY TXC-06312B-MB, Ed. 2
June 2005
PHAST-12N Device
DATA SHEET
TXC-06312B
The placement of these resistors should be near the PHAST-12N in AC coupled mode and
near the optical transceiver in DC coupled mode.
Provide optional 0.1 F series capacitors on all P and N lines between the PHAST-12N and
each optical transceiver. This allows for both AC- and DC-coupling: 0
mounted in case of DC coupling.
At the optical transceiver side, one should carefully follow the recommendations in the data
sheet of the optical transceiver. This should satisfy most vendors’ data sheets:
LVPECL - Tx Reference Clock:
It is required to provide a pull-up and a pull-down resistor as close as possible to the
REFTXCLK2P & REFTXCLK2N pins on the PHAST-12N:
One should follow the recommendations in the data sheet of the oscillator.
To achieve optimal jitter performance, it is recommended to connect a differential oscillator to
REFTXCLK2P/N (LVPECL), instead of a single-ended to REFTXCLK1 (LVTTL).
LVPECL - PCB guidelines:
The differential pairs (P and N) will be routed together, have a controlled impedance of 50
and be the same length. Make them as short as possible and in as straight a path as
possible. Vias should be avoided if practicable.
LVPECL - Unused pins:
All unused LVPECL inputs can be left floating (no resistors required).
All unused LVPECL outputs can be left floating (no resistors required).
• Provide pull-up and pull-down resistors as close as possible to the optical transceiver’s
• Provide pull-up and pull-down resistors as close as possible to the optical transceiver’s
• Provide a resistor between P and N as close as possible to the optical transceiver’s Tx
• Provide enough resistors in the schematic. Some of them may not be required, and can
• pull-up value (towards +3.3V) = 130
• pull-down value (towards VSS) = 82
• Typically, pull-down resistors of approx. 150
• Provide enough resistors in the schematic. Some of them may not be required, and can
Rx output, on both P and N (Usually, only pull-down resistors are required).
Tx input, on both P and N.
input.
be treated as ‘do not install’.
oscillator outputs.
be treated as ‘do not install’.
-
Selected Parameter Values
-
on both P and N are required, close to the
resistors can be
4 8 o f 2 0 2