MT90840AP Zarlink, MT90840AP Datasheet - Page 18

• Manufacturer Part Number: MT90840AP
• Description: Switch Fabric 512 x 2430/512 x 512/2.373K x 2.373K 5V 84-Pin PLCC Tube
• Manufacturer: Zarlink

Specifications of MT90840AP

• Package: 84PLCC
• Number Of Ports: 16
• Fabric Size: 512 x 2430|512 x 512|2.373K x 2.373K
• Switch Core: Non-Blocking
• Port Speed: 8.192|4.096|2.048 Mbps
• Operating Supply Voltage: 5 V

Timing Mode 3 (TM3) - Bus Slave
Synchronous Parallel Port With ST-BUS Clock Slave
Timing Mode 3 is used where the main TDM clock reference resides on the parallel port side of the system, and
where the receive parallel port and the transmit parallel port are aligned. (An example is a node on a backplane.)
Timing on the serial port is tightly tied to the receive parallel port, and the transmit parallel port is clocked by the
receive parallel port clock. In TM3, PCKT and PPFTo are not used. See Figure 7 for a connection example.
In TM3, the MT90840 timing is controlled by the parallel port frame pulse (PPFRi) and clock (PCKR). The MT90840
generates the serial port output frame pulse (F0o) locked to PPFRi. TM3 is similar to TM2 with two main
differences: the parallel Bypass Path is disabled, and the parallel port receive and transmit buses are synchronized
and both aligned with PPFRi. A fixed offset exists between F0o and PPFRi due to serial-to-parallel conversion. The
MT90840 will align F0o so that it proceeds PPFRi by 3.8 µsec.
In TM3 the internal clock divider circuit is always enabled, regardless of the state of the INTCLK bit (C4/8R1 and
C4/8R2 are unused). Therefore TM3 is limited to 19.44 and 16.384 Mbyte/s parallel port rates, and 2.048 and
4.096 Mbps serial port rates.
Source
8 kHz
8
8
8
8
8 kHz TX
Data TX
Data RX
8 kHz RX
Data TX
Data RX
Figure 6b - TM2 Multiple-MT90840 Configuration
TX/RX Clock
PCKR
PCKR
PPFT
PDo0-7
PDi0-7
PPFRi
PPFT
PDo0-7
PDi0-7
PPFRi
Zarlink Semiconductor Inc.
MT90840
MT90840
SFDI = 0
SFDI = 1
MT90840
C4/8R1 & 2
C4/8R1 & 2
18
PLL
4.096 MHz or
8.192 MHz
SPCKo
SPCKo
STo0-7
STo0-7
STi0-7
STi0-7
F0o
F0i
CPU
8
8
8
8
CPU
4.096 MHz
8 kHz
STi/o 0-7
STi/o 0-7
(8.192 MHz)
STi/o 0-7
STi/o 0-7
4.096 MHz
Components
ST-BUS
Data Sheet