PCK940L

General description

The PCK940L is a 1 : 18 low voltage clock distribution chip with 2.5 V or 3.3 V LVCMOS output capabilities. The device features the capability to select either a differential LVPECL or an LVCMOS compatible input. The 18 outputs are 2.5 V or 3.3 V LVCMOS compatible and feature the drive strength to drive 50 Ohm series or parallel terminated transmission lines. With output-to-output skews of 150 ps, the PCK940L is ideal as a clock distribution chip for the most demanding of synchronous systems. The 2.5 V outputs also make the device ideal for supplying clocks for a high performance microprocessor based design.

With a low output impedance of approximately 20 Ohm, in both the HIGH and LOW logic states, the output buffers of the PCK940L are ideal for driving series terminated transmission lines. With an output impedance of 20 Ohm, the PCK940L has the capability of driving two series terminated transmission lines from each output. This gives the PCK940L an effective fan-out of 1 : 36. If a lower output impedance is desired, please see the PCK942C data sheet.

The differential LVPECL inputs of the PCK940L allow the device to interface directly with a LVPECL fan-out buffer like the PCKEP111 to build very wide clock fan-out trees or to couple to a high frequency clock source. The LVCMOS input provides a more standard interface for applications requiring only a single clock distribution chip at relatively low frequencies. In addition, the two clock sources can be used to provide for a test clock interface as well as the primary system clock. A logic HIGH on the LVCMOS_CLKSEL pin will select the LVCMOS level clock input. All inputs of the PCK940L have internal pull-up/pull-down resistors so they can be left open if unused.

The PCK940L is a single or dual supply device. The device power supply offers a high degree of flexibility. The device can operate with a 3.3 V core and 3.3 V output, a 3.3 V core and 2.5 V outputs, as well as a 2.5 V core and 2.5 V outputs. The 32-lead LQFP package was chosen to optimize performance, board space and cost of the device. The 32-lead LQFP package has a 7 mm x 7 mm body size with a conservative 0.8 mm pin spacing.

Features

• LVPECL or LVCMOS clock input
• 2.5 V LVCMOS outputs for Pentium II microprocessor support
• 150 ps maximum output-to-output skew
• Maximum output frequency of 250 MHz at 3.3 V V_CC
• 32-lead LQFP packaging
• Dual or single supply voltage:
• Dual V_CC supply voltage, 3.3 V core and 2.5 V output
• Single 3.3 V V_CC supply voltage for 3.3 V outputs
• Single 2.5 V V_CC supply voltage for 2.5 V I/O

Block diagrams/pinning

Print / Email

• Print this information
• Email this information

Disclaimer

The information published on product information pages of the www.nxp.com or www.semiconductors.com websites is an extract from product data sheets and is for information purposes only. For detailed information please check the most recent version of the relevant product data sheet as published on these websites. In the event of any conflict between product information pages and data sheets or deviations from information provided in the product data sheets on these product information pages, the information provided in the product data sheets shall prevail.

The product status of the product(s) described in the product data sheet may have changed since publication of the data sheet and therefore information in datasheets on product status may be outdated. The latest information on product status is published on the product information pages of the above-mentioned websites.

As from October 1st, 2006 Philips Semiconductors has a new trade name - NXP Semiconductors, which will be used in future data sheets together with new contact details. In data sheets where the previous Philips references remain, please use the new links as shown below.

http://www.philips.semiconductors.com use http://www.nxp.com

http://www.semiconductors.philips.com use http://www.nxp.com (Internet)

sales.addresses@www.semiconductors.philips.com use salesaddresses@nxp.com (e-mail)

The copyright notice at the bottom of each page (or elsewhere in the document, depending on the version)
- © Koninklijke Philips Electronics N.V. (year). All rights reserved -
is replaced with:
- © NXP B.V. (year). All rights reserved.-

If you have any questions related to the data sheet, please contact our nearest sales office via e-mail or phone (details via salesaddresses@nxp.com). Thank you for your cooperation and understanding.