The TKL2500 is a member of the transceiver family of multigigabit transceivers used in ultrahigh-speed bidirectional point-to-point data transmission systems. The TKL2500 supports an effective serial interface speed of 1.5 Gbps to 2.5 Gbps, providing up to 2 Gbps of data bandwidth. The TKL2500 is pin-for-pin compatible with the TLK2500. The TKL2500 is both pin-for-pin compatible with and functionally identical to the TLK1501, a 0.6 to 1.5 Gbps transceiver, and the TLK3101, a 2.5 to 3.125 Gbps transceiver, providing a wide range of performance solutions with no required board layout changes.
The primary application of this chip is to provide very high-speed I/O data channels for point-to-point baseband data transmission over controlled impedance media of approximately 50 ?. 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.
This device can also be used to replace parallel data transmission architectures by providing a reduction in the number of traces, connector terminals, and transmit/receive terminals. 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. It 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 TKL2500 performs data conversion parallel-to-serial and serial-to-parallel. The clock extraction functions as a physical layer interface device. The serial transceiver interface operates at a maximum speed of 2.5 Gbps. The transmitt
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The TKL2500 is housed in a high-performance, thermally enhanced, 64-pin VQFP (RCP64) 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. Therefore, if not implementing PowerPAD PCB features, the use of solder masks (or other assembly techniques) may be required to prevent any inadvertent shorting by the exposed PowerPAD to connection etches or vias under the package. It is strongly recommended that the PowerPAD be soldered to the thermal land. The recommended convention, however, is to not run any etches or signal vias under the device, but to have only a grounded thermal land as explained below. Although the actual size of the exposed die pad may vary, the minimum size required for the keep-out area for the 64-pin PFP PowerPAD package is 8 mm X 8 mm.
It is recommended that there be a thermal land, which is an area of solder-tinned-copper, underneath the PowerPAD package. The thermal land varies in size depending on the PowerPAD package being used, the PCB construction, and the amount of heat that needs to be removed. In addition, the thermal land may or may not contain numerous thermal vias depending on PCB construction.
Other requirements for thermal lands and thermal vias are detailed in the TI application note PowerPAD Thermally Enhanced Package Application Report, TI literature number SLMA002, available via the TI Web pages beginning at URL: http://www.ti.com.
For the TKL2500, this thermal land should be grounded to the low-impedance ground plane of the device. This improves not only thermal performance but also the electrical grounding of the device. It is also recommended that the device ground terminal landing pads be connected directly to the grounded thermal la
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