xrt94l33 Exar Corporation, xrt94l33 Datasheet - Page 36

• Manufacturer Part Number: xrt94l33
• Description: Multi-channel, Multi-function Device Aggregates 3 Ds3/e3/sts-1 Into Oc3/stm-1
• Manufacturer: Exar Corporation

XRT94L33
Rev.1.2.0.
AB16
E12
E17
TxOH_0
TxOH_1
TxOH_2
3-CHANNEL DS3/E3/STS-1 TO STS-3/STM-1 MAPPER IC DATA SHEET
I
TTL
Continued
If the user is only inserting POH data via these input pins:
In this mode, the external circuitry (which is being interfaced to
the “Transmit Path Overhead Input Port” is suppose to monitor
the following output pins.
• TxOHFrame_n
• TxOHEnable_n
• TxOHClk_n
The “TxOHFrame_n” output pin will toggle “high” upon the
falling edge of “TxOHClk_n” approximately one “TxOHClk_n”
period prior to the “TxOH” port being ready to accept and
process the first bit within J1 byte (e.g., the first POH byte).
The “TxOHFrame_n” output pin will remain “high” for eight
consecutive “TxOHClk_n” periods.
should use this pin to note STS-1 SPE frame boundaries.
The “TxOHEnable_n” output pin will toggle “high” upon the
falling edge of “TxOHClk_n” approximately one “TxOHClk_n”
period prior to the “TxOH” port being ready to accept and
process the first bit within a given POH byte.
wishes to externally insert a given POH byte;
This data bit will be sampled upon the very next falling edge of
“TxOHClk_n”. The external circuitry should continue to keep
the “TxOHIns_n” input pin “high” and advancing the next bits
(within the POH bytes) upon each rising edge of “TxOHClk_n”.
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(1) assert the “TxOHIns_n” input pin by toggling it “high”,
(2) place the value of the first bit (within this particular
and
POH byte) on this input pin upon the very next falling
edge of “TxOHClk_n”.
The external circuitry
xr
If the user