CY7C6800
Document #: 38-08016 Rev. *H Page 2 of 14
2.0 Applications
• DSL modems
• ATA interface
• Memory card readers
• Legacy conversion devices
• Cameras
• Scanners
• Home PNA
• Wireless LAN
• MP3 players
•Networking
3.0 Functional Overview
3.1 USB Signaling Speed
TX2 operates at two of the rates defined in the USB Specifi-
cation 2.0, dated April 27, 2000:
• Full speed, with a signaling bit rate of 12 Mbps
• High speed, with a signaling bit rate of 480 Mbps
TX2 does not support the low-speed (LS) signaling rate of 1.5
Mbps.
3.2 Transceiver Clock Frequency
TX2 has an on-chip oscillator circuit that uses an external 24-
MHz (±100-ppm) crystal with the following characteristics:
• Parallel resonant
• Fundamental mode
•500-μW drive level
• 27–33 pF (5% tolerance) load capacitors
An on-chip phase-locked loop (PLL) multiplies the 24-MHz
oscillator up to 30/60 MHz, as required by the transceiver
parallel data bus. The default UTMI interface clock (CLK)
frequency is determined by the DataBus16_8 pin.
3.3 Buses
The two packages allow for 8/16-bit bidirectional data bus for
data transfers to a controlling unit.
3.4 Reset Pin
An input pin (Reset) resets the chip. This pin has hysteresis
and is active HIGH according to the UTMI specification. The
internal PLL stabilizes approximately 200 μs after V
CC
has
reached 3.3V.
3.5 Line State
The Line State output pins LineState[1:0] are driven by combi-
national logic and may be toggling between the J and the K
states. They are synchronized to the CLK signal for a valid
signal. On the CLK edge the state of these lines reflect the
state of the USB data lines. Upon the clock edge the 0-bit of
the LineState pins is the state of the DPLUS line and the one
bit of LineState is the DMINUS line. When synchronized, the
set up and hold timing of the LineState is identical to the
parallel data bus.
3.6 Full-speed vs. High-speed Select
The FS vs. HS is done through the use of both XcvrSelect and
the TermSelect input signals. The TermSelect signal enables
the 1.5 K ohm pull up on to the DPLUS pin. When TermSelect
is driven LOW, a SE0 is asserted on the USB providing the HS
termination and generating the HS Idle state on the bus. The
XcvrSelect signal is the control which selects either the FS
transceivers or the HS transceivers. To select the HS trans-
ceivers, set this pin to ‘0’. To select the FS transceivers, set
this pin to ‘1’.
3.7 Operational Modes
The operational modes are controlled by the OpMode signals.
The OpMode signals are capable of inhibiting normal
operation of the transceiver and evoking special test
modes.
These modes take effect immediately and take precedence
over any pending data operations. The transmission data rate
when in OpMode depends on the state of the XcvrSelect
input.
Mode 0 allows the transceiver to operate with normal USB
data decoding and encoding.
Mode 1 allows the transceiver logic to support a soft
disconnect feature which three-states both the HS and FS
transmitters, and removes any termination from the USB,
making it appear to an upstream port that the device has been
disconnected from the bus.
Mode 2 disables Bit Stuff and NRZI encoding logic so 1s
loaded from the data bus becomes Js on the DPLUS/DMINUS
lines and 0s become Ks.
4.0 DPLUS/DMINUS Impedance Termination
The CY7C68000 does not require external resistors for USB
data line impedance termination or an external pull up resistor
on the DPLUS line. These resistors are incorporated into the
part. They are factory trimmed to meet the requirements of
USB 2.0. Incorporating these resistors also reduces the pin
count on the part.
OpMode[1:0] Mode Description
00 0 Normal operation
01 1 Non-driving
10 2 Disable Bit Stuffing and
NRZI encoding
11 3 Reserved
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