TLK2521

1.0 to 2.5 Gbps 18BIT SERDES

SLLS574D − JULY 2003 − REVISED JULY 2007

2

POST OFFICE BOX 655303

description

The TLK2521 is a member of the WizardLink family of multi-gigabit transceivers, intended for use in high-speed

bidirectional point-to-point data transmission systems. The TLK2521 supports an effective serial interface

speed of 1 Gbps to 2.5 Gbps, providing up to 2.25 Gbps of data bandwidth.

The primary application of the TLK2521 is to provide high-speed I/O data channels for point-to-point baseband

data transmission over controlled impedance media of approximately 50

Ω. The transmission media can be

printed circuit board, copper cables, or fiber-optic cable. The maximum rate and distance of data transfer is

dependent upon the attenuation characteristics of the media and the noise coupling to the environment.

The TLK2521 can also be used to replace parallel data transmission architectures by providing a reduction in

the number of traces, connector pins, and transmit/receive pins. Parallel data loaded into the transmitter is

delivered to the receiver over a serial channel, which can be a coaxial copper cable, a controlled impedance

backplane, or an optical link. The data is then reconstructed into its original parallel format. It offers significant

power and cost savings over current solutions, as well as scalability for higher data rate in the future.

The TLK2521 performs the data parallel-to-serial, serial-to-parallel conversion, and clock extraction functions

for a physical layer interface device. The serial transceiver interface operates at a maximum speed of 2.5 Gbps.

The transmitter latches 18-bit parallel data at a rate based on the supplied reference clock (GTX_CLK). The

18-bit parallel data is internally encoded into 20 bits by framing the 18-bit data with a start and a stop bit. The

resulting 20-bit word is then transmitted differentially at 20 times the reference clock (GTX_CLK) rate. The

receiver section performs the serial-to-parallel conversion on the input data synchronizing the resulting 20-bit

wide parallel data to the extracted reference clock (RX_CLK). It then extracts the 18 bits of data from the 20-bit

wide data resulting in 18 bits of parallel data at the receive data pins (RXD0−17). This results in an effective data

payload of 900 Mbps to 2.25 Gbps (18 bits data x GTX_CLK frequency).

The TLK2521 is housed in a high performance, thermally enhanced, 64-pin HTQFP PowerPAD package. Use

of the PowerPAD package does not require any special considerations except to note that the PowerPAD, which

is an exposed die pad on the bottom of the device, is a metallic thermal and electrical conductor. It is strongly

recommended that the TLK2521 PowerPAD be soldered to the grounded thermal land on the board, since the

PowerPAD also constitutes a major electrical ground connection for the TLK2521. All ac performance

specifications in this data sheet are measured with the PowerPAD soldered to the test board.

The TLK2521 provides an internal loopback capability for self-test purposes. Serial data from the serializer is

passed directly to the deserializer allowing the protocol device a functional self-check of the physical interface.

The TLK2521 is designed to be hot plug capable. An on-chip power-on reset circuit holds the RX_CLK low and

places the parallel side output signal pins, DOUTTXP and DOUTTXN, into a high-impedance state during power

up.

The TLK2521 uses a 2.5-V supply. The I/O section is 3-V compatible. The TLK2521 is characterized for

operation from −40

°C to 85°C.