28478G-18 Mindspeed Technologies, 28478G-18 Datasheet - Page 72

• Manufacturer Part Number: 28478G-18
• Description: Multichannel Synchronous Communications Controller 208-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of 28478G-18

• Package: 208BGA
• Maximum Data Rate: 32768 Kbps
• Transmission Media Type: Wire
• Power Supply Type: Analog
• Typical Supply Current: 250 mA
• Typical Operating Supply Voltage: 3.3 V
• Minimum Operating Supply Voltage: 3 V
• Maximum Operating Supply Voltage: 3.6 V

Serial Interface
4.5.3
Frame Synchronization Flywheel
MUSYCC utilizes the TSYNC and RSYNC signals to maintain a timebase which keeps track of the active bit in the
current time slot. The mechanism is referred to as the frame synchronization flywheel. The flywheel counts the
number of bits per frame and automatically rolls over the bit count according to the programmed mode. The
TSYNC or RSYNC input marks the first bit in the frame. The mode specified in the PORTMD bit field
(Table 5-
12, Port Configuration
Descriptor), determines the number of bits in the frame. A flywheel exists for both the
transmit and receive functions for every port.
The flywheel is synchronized when MUSYCC detects TSYNC = 1 or RSYNC = 1, for transmit or receive functions,
respectively. Once synchronized, the flywheel maintains synchronization without further assertion of the
synchronization signal.
A time slot counter within each port is reset at the beginning of each frame and tracks the current time slot being
serviced.
For the Nx64 mode, the value of N cannot be specified; therefore, the data requires a synchronization pulse every
frame period to reset the flywheel. Also, in Nx64 mode, the TSYNC must precede the output of bit 0 of the frame by
four line clock periods.
Figures 4-2
through
4-4
illustrate the timing relationships between the data and the synchronization signal for
various modes of operation.
®
Mindspeed Technologies
59
28478-DSH-002-E
Preliminary Information / Mindspeed Proprietary and Confidential