
MT90500
29
The CLKx2 signal can be selected as single-ended or differential. (Differential CLKx2 allows com-
patibility with the H-MVIP bus.) In TDM Timing Slave, the CLKx2 signal can be input on the CLKx2
pin, or the differential CLKx2PI and CLKx2NI pins. This selection is made with CLKTYPE in the
TDM Bus Type Register at address 6010h. In TDM Timing Master, the CLKx2 signal is output on
the CLKx2/CLKx2PO pin, and an inverted clock is available on the CLKx2NO pin.
The MT90500 supports the following TDM timing modes:
TDM Timing Bus Slave - CLKx2 Reference
(CLKMASTER = ‘0’ in TDM Bus Type Register at 6010h)
In this mode, the MT90500 is configured as a TDM Timing Slave and all internal TDM timing is synchronized to
the TDM clock inputs: CLKx2, CLKx1, and FSYNC. The following sub-modes are also selectable:
The CLKx1 can be an input at the CLKx1 pin, or it can be derived internally from CLKx2. This is
controlled by TCLKSYN (address 6010h). If the CLKx1 pin is not used as an input in TDM Slave
mode, it remains high-impedance.
TDM Timing Slave operation takes its 8 kHz framing from the FSYNC input pin, which would usu-
ally be driven by the TDM bus. To support other implementations, the REF8KCLK output remains
active in TDM Slave mode. An 8 kHz reference output can be made available at REF8KCLK,
selectable from the EX_8KA input, the SEC8K pin, or one of the internal dividers. In addition, the
FREERUN output can be used to monitor the presence of REF8KCLK.
Main TDM
Bus Timing
and
Clock
Generation
Logic
0
1
2
3
External
PLL
(Optional)
CLKx2
FSYNC
EX_8KA
MCLK
RXVCLK
REF8KCLK
0
1
PLLCLK
SEC8K
0
1
Figure 3 - TDM Clock Selection and Generation Logic
CLKx2
CLKx1
FSYNC
Master/Slave
Clock Absent
Detection
Logic
SEC8KEN
FREERUN
Local TDM
Bus
Clock
Generation
Logic
LOCx2
LOCx1
LSYNC
L
M
MT9041 or
other PLL
CLK16
(16.384 MHz)
0
1
SEC8K_INT
EX_8KA_INT
REFSEL<1:0>
DIVCLK_SRC
BEPLL
SEC8KSEL
Adaptive
Clock
Recovery
ATM Cells
Divide by 2
to 16384
Divide by
1,2,4,or 8
FSYNC
EX_8KA_INT
REF8KCLK
Detection
Logic
External CPU Bus
I
FS_INT
FS_INT
DIV1...8
PHLEN
Square
Square
SEC8K_SQ
EX_8KA_SQ
All control bits shown are in Master Clock Generation Control Register (6090h).
1 0
1
0
CLKx1
MT90500
SRTS Clock
Recovery
FNXI
SRTS