DS26522 Dual T1/E1/J1 Transceiver
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NAME
PIN
TYPE
FUNCTION
D[2]/
SPI_SCLK
M2
I
Data [2]/SPI Serial Interface Clock
D[2]: Bit 2 of the 8-bit data bus used to input data during register writes, and data
outputs during register reads. Not driven when both
CSB1 and CSB2 = 1.
SPI_SCLK:
SPI serial clock input when SPI_SEL = 1.
D[1]/
SPI_MOSI
L3
I
Data [1]/SPI Serial Interface Data Master-Out/Slave-In
D[1]: Bit 1 of the 8-bit data bus used to input data during register writes, and data
outputs during register reads. Not driven when both
CSB1 and CSB2 = 1.
SPI_MOSI:
SPI serial data input (master-out/slave-in) when SPI_SEL = 1.
D[0]/
SPI_MISO
M3
I
Data [0]/SPI Serial Interface Data Master-In/Slave-Out
D[0]: Bit 0 of the 8-bit data bus used to input data during register writes, and data
outputs during register reads. Not driven when both
CSB1 and CSB2 = 1.
SPI_MISO:
SPI serial data output (master-in/slave-out) when SPI_SEL = 1.
CSB1
L4
CSB2
M4
I
Chip-Select Bar.
This active-low signal is used to qualify register read/write
accesses. The
RDB/DSB and WRB signals are qualified with CSB1 and CSB2.
CSB1 and CSB2 must not be active at the same time. If CSB1 is active, channel
one is accessed for reading or writing. If
CSB2 is active, channel two is accessed.
RDB/
DSB
H3
I
Read-Data Bar/Data-Strobe Bar.
This active-low signal along with
CSB qualifies
read access to one of the DS26522 registers. The DS26522 drives the data bus
with the contents of the addressed register while
RDB is low and CSB1 or CSB2 is
low.
WRB/
RWB
J3
I
Write-Read Bar/Read-Write Bar.
This active-low signal along with
CSBn qualifies
write access to one of the DS26522 registers. Data at D[7:0] is written into the
addressed register at the rising edge of
WRB while CSB1 or CSB2 is low.
SPI_SEL
D7
I
SPI Serial Bus Mode Select
SPI: 0 = Parallel Bus Mode, 1 = SPI Serial Bus Mode
INTB
K4
U
Interrupt Bar.
This active-low, open-drain output is asserted when an unmasked
interrupt event is detected.
INTB will be deasserted when all interrupts have been
acknowledged and serviced. Extensive mask bits are provided at the global level,
framer, LIU, and BERT level.
BTS
E5
I
Bus Type Select.
Set high to select Motorola bus timing, low to select Intel bus
timing. This pin controls the function of the
RDB/DSB and WRB pins.
SYSTEM INTERFACE
MCLK
M9
I
Master Clock.
This is an independent free-running clock whose input can be a
multiple of 2.048MHz ±50ppm or 1.544MHz ±50ppm. The clock selection is
available by bits MPS0 and MPS1 and FREQSEL. Multiple of 2.048MHz can be
internally adapted to 1.544MHz. Multiple of 1.544MHz can be adapted to
2.048MHz. Note that TCLK must be 2.048MHz for E1 and 1.544MHz for T1/J1
RESETB
K3
I
Reset Bar.
Active-low reset. This input forces the complete DS26522 reset. This
includes reset of the registers, framers, and LIUs.
REFCLKIO1
K8
REFCLKIO2
L10
I/O
Reference Clock Input/Output
Input: A 2.048MHz or 1.544MHz clock input. This clock can be used to generate
the backplane clock. This allows for the users to synchronize the system
backplane with the reference clock. The other options for the backplane clock
reference are LIU-received clocks or MCLK.
Output:
This signal can also be used to output a 1.544MHz or 2.048MHz reference
clock. This allows for multiple DS26522s to share the same reference for
generation of the backplane clock. Hence, in a system consisting of multiple
DS26522s, one can be a master and others a slave using the same reference
clock.