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DS26521 Single T1/E1/J1 Transceiver
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NAME
PIN
TYPE
FUNCTION
RCHBLK/
CLK
49
O
Receive Channel Block/Receive Channel Block Clock.
This pin can be
configured to output either RCHBLK or RCHCLK. RCHBLK is a user-
programmable output that can be forced high or low during any of the 24 T1 or 32
E1 channels. It is synchronous with RCLK when the receive-side elastic store is
disabled. It is synchronous with RSYSCLK when the receive-side elastic store is
enabled. This pin is useful for blocking clocks to a serial UART or LAPD controller
in applications where not all channels are used such as fractional service, 384kbps
service, 768kbps, or ISDN-PRI. Also useful for locating individual channels in drop-
and-insert applications, for external per-channel loopback, and for per-channel
conditioning.
RCHCLK.
RCHCLK is a 192kHz (T1) or 256kHz (E1) clock that pulses high during
the LSB of each channel. It is synchronous with RCLK when the receive-side
elastic store is disabled. It is synchronous with RSYSCLK when the receive-side
elastic store is enabled. It is useful for parallel-to-serial conversion of channel data.
BPCLK
48
O
Backplane Clock.
Programmable clock output that can be set to 2.048MHz,
4.096MHz, 8.192MHz, or 16.384MHz. The reference for this clock can be RCLK
from any of the LIU, 1.544MHz, or 2.048MHz frequency derived from MCLK or an
external reference clock. This allows for the IBO clock to reference from an
external source or the T1/J1/E1 recovered clock or the MCLK oscillator.
MICROPROCESSOR INTERFACE
A12
14
A8
15
A7
16
A6
17
A5
18
A4
19
A3
20
A2
23
A1
24
A0
25
I
Address [12], [8:0].
This bus selects a specific register in the DS26521 during
read/write access. A12 is the MSB and A0 is the LSB. Note: A9, A10, and A11 are
internally pulled low. Connect device A12 to microprocessor A12 to ensure
software compatibility with other TEX-series transceivers. See Section
9 for further
information.
D[7]/
SPI_CPOL
26
I
Data [7]/SPI Interface Clock Polarity
D[7]: Bit 7 of the 16-bit or 8-bit data bus used to input data during register writes
and data outputs during register reads. Not driven when
CS = 1.
SPI_CPOL:
This signal selects the clock polarity when SPI_SEL = 1. See Section
8.1.3 for detailed timing and functionality information. Default setting is low.
D[6]/
SPI_CPHA
27
I
Data [6]/SPI Interface Clock Phase
D[6]: Bit 6 of the 16-bit or 8-bit data bus used to input data during register writes,
and data outputs during register reads. Not driven when
CS = 1.
SPI_CPHA:
This signal selects the clock phase when SPI_SEL = 1. See Section
8.1.3 for detailed timing and functionality information. Default setting is low.
D[5]/
SPI_SWAP
28
I
Data [5]/SPI Bit Order Swap
D[5]: Bit 5 of the 16-bit or 8-bit data bus used to input data during register writes,
and data outputs during register reads. Not driven when
CSB = 1.
SPI_SWAP:
This signal is active when SPI_SEL = 1. The address and data bit
order is swapped when SPI_SWAP is high. The R/W and B bit positions are never
changed in the control word.
0 = LSB is transmitted and received first.
1 = MSB is transmitted and received first.
D[4]
29
I
Data [4].
Bit 4 of the 8-bit data bus used to input data during register writes, and
data outputs during register reads. Not driven when
CSB = 1.
D[3]
30
I
Data [3].
Bit 3 of the 8-bit data bus used to input data during register writes, and
data outputs during register reads. Not driven when
CSB = 1.