
DS26522 Dual T1/E1/J1 Transceiver 
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NAME 
PIN 
TYPE 
FUNCTION 
RECEIVE FRAMER 
RSER1 
K5 
RSER2 
H12 
O 
Received Serial Data. 
Received NRZ serial data. Updated on rising edges of 
RCLK when the receive-side elastic store is disabled. Updated on the rising edges 
of RSYSCLK when the receive-side elastic store is enabled. 
When IBO mode is used, the RSER pins can output data for multiple framers. The 
RSER data is synchronous to RSYSCLK. This is described in Section 
8.8.2
. 
RCLK1 
L8 
RCLK2 
L9 
O 
Receive Clock. 
A 1.544MHz (T1) or 2.048MHz (E1) clock that is used to clock 
data through the receive-side framer. This clock is recovered from the signal at 
RTIP and RRING. RSER data is output on the rising edge of RCLK. RCLK is used 
to output RSER when the elastic store is not enabled or IBO is not used. When the 
elastic store is enabled or IBO is used, the RSER is clocked by RSYSCLK. 
Receive System Clock. 
1.544MHz, 2.048MHz, 4.096MHz, 8.192MHz, or 
16.384MHz receive backplane clock. Only used when the receive-side elastic store 
function is enabled. Should be tied low in applications that do not use the receive-
side elastic store. Multiple of 2.048MHz is expected when the IBO mode is used. 
Note that RSYSCLK is used for both transceivers. 
Receive Synchronization. 
If the receive-side elastic store is enabled, then this 
signal is used to input a frame or multiframe boundary pulse. If set to output frame 
boundaries, then RSYNC can be programmed to output double-wide pulses on 
signaling frames in T1 mode. In E1 mode, RSYNC out can be used to indicate 
CAS and CRC-4 multiframe. The DS26522 can accept H.100-compatible 
synchronization signal. The default direction of this pin at power-up is input, as 
determined by the RSIO control bit in the 
RIOCR
.2 register. 
Receive Multiframe/Frame Synchronization. 
A dual function pin to indicate 
frame or multiframe synchronization. RFSYNC is an extracted 8kHz pulse, one 
RCLK wide that identifies frame boundaries. RMSYNC is an extracted pulse, one 
RCLK wide (elastic store disabled) or one RSYSCLK wide (elastic store enabled), 
that identifies multiframe boundaries. When the receive elastic store is enabled, 
the RMSYNC signal indicates the multiframe sync on the system (backplane) side 
of the elastic store. In E1 mode, this pin can indicate either the CRC-4 or CAS 
multiframe as determined by the RSMS2 control bit in the Receive I/O 
Configuration register (
RIOCR
.1). 
RSYSCLK1 
J8 
RSYSCLK2 
J11 
I 
RSYNC1 
K7 
RSYNC2 
K12 
I/O 
RMSYNC1/ 
RFSYNC1 
G6 
RMSYNC2/ 
RFSYNC2 
L12 
O 
RSIG1 
H6 
RSIG2 
L11 
O 
Receive Signaling. 
Outputs signaling bits in a PCM format. Updated on rising 
edges of RCLK when the receive-side elastic store is disabled. Updated on the 
rising edges of RSYSCLK when the receive-side elastic store is enabled. 
AL/ 
RSIGF/ 
FLOS1 
F6 
AL/ 
RSIGF/ 
FLOS2 
J12 
O 
Analog Loss/Receive-Signaling Freeze/Framer LOS. 
Analog LOS reflects the 
LOS (loss of signal) detected by the LIU front-end and framer LOS is LOS 
detection by the corresponding framer; the same pins can reflect receive-signaling 
freeze indications. This selection can be made by settings in the Global 
Transceiver Clock Control register (
GTCCR
 ). 
If framer LOS is selected, this pin can be programmed to toggle high when the 
framer detects an LOS condition, or when the signaling data is frozen via either 
automatic or manual intervention. The indication is used to alert downstream 
equipment of the condition. 
Receive Loss of Frame/Loss of Transmit Clock. 
This pin can be programmed to 
either toggle high when the synchronizer is searching for the frame and multiframe, 
or to toggle high if the TCLK pin has not been toggled for approximately three clock 
periods. 
RLF/ 
LTC1 
RLF/ 
LTC2 
M12 
O