Electronic Components Datasheet Search |
|
WED3C755E8M350BC Datasheet(PDF) 11 Page - White Electronic Designs Corporation |
|
WED3C755E8M350BC Datasheet(HTML) 11 Page - White Electronic Designs Corporation |
11 / 14 page WED3C755E8M-XBX 11 White Electronic Designs Corporation • (602) 437-1520 • www.wedc.com White Electronic Designs White Electronic Designs Corp. reserves the right to change products or specifications without notice. May, 2003 Rev 2 FIG. 6 - POWER SUPPLY FILTER CIRCUIT PLL POWER SUPPLY FILTERING The AVCC and L2AVCC power signals are provided on the WED3C755E8M-XBX to provide power to the clock generation phase-locked loop and L2 cache delay-locked loop respectively. To ensure stability of the internal clock, the power supplied to the AVCC input signal should be filtered of any noise in the 500kHz to 10 MHz resonant frequency range of the PLL. A circuit similar to the one shown in Figure 6 using surface mount capacitors with minimum Effective Series Inductance (ESL) is recommended. Multiple small capacitors of equal value are recommended over a single large value capacitor. The circuit should be placed as close as possible to the AVCC pin to minimize noise coupled from nearby circuits. An identical but separate circuit should be placed as close as possible to the L2AVCC pin. It is often possible to route directly from the capacitors to the AVCC pin, which is on the periphery of the 255 BGA footprint, without the inductance of vias. The L2AVCC pin may be more difficult to route but is proportionately less critical. PULL-UP RESISTOR REQUIREMENTS The WED3C755E8M-XBX requires pull-up resistors (1 kW-5 kW) on several control pins of the bus interface to maintain the control signals in the negated state after they have been actively negated and released by the processor or other bus masters. These pins are TS#, ABB#, AACK#, ARTRY#, DBB#, DBWO#, TA#, TEA#, and DBDIS#. DRTRY# should also be connected to a pull-up resistor (1 kW-5 kW) if it will be used by the system; otherwise, this signal should be connected to HRESET# to select NO-DRTRY mode. Three test pins also require pull-up resistors (100 W-1 kW). These pins are L1_TSTCLK, L2_TSTCLK, and LSSD_ MODE#. These signals are for factory use only and must be pulled up to OVCC for normal machine operation. In addition, CKSTP_OUT# is an open-drain style output that requires a pull-up resistor (1 kW-5 kW) if it is used by the system. During inactive periods on the bus, the address and transfer attributes may not be driven by any master and may, therefore, float in the high-impedance state for relatively long periods of time. Since the processor must continually monitor these signals for snooping, this float condition may cause additional power draw by the input receivers on the processor or by other receivers in the system. These signals can be pulled up through weak (10 kW) pull-up resistors by the system or may be otherwise driven by the system during inactive periods of the bus to avoid this additional power draw, but address bus pull-up resistors are not neccessary for proper device operation. The snooped address and transfer attribute inputs are: A[0:31], AP[0:3], TT[0:4], TBST#, and GBL#. The data bus input receivers are normally turned off when no read operation is in progress and, therefore, do not require pull-up resistors on the bus. Other data bus receivers in the system, however, may require pull-ups, or that those signals be otherwise driven by the system during inactive periods by the system. The data bus signals are: DH[0:31], DL[0:31], and DP[0:7]. If 32-bit data bus mode is selected, the input receivers of the unused data and parity bits will be disabled, and their outputs will drive logic zeros when they would otherwise normally be driven. For this mode, these pins do not require pull-up resistors, and should be left unconnected by the system to minimize possible output switching. If address or data parity is not used by the system, and the respective parity checking is disabled through HID0, the input receivers for those pins are disabled, and those pins do not require pull-up resistors and should be left unconnected by the system. If all parity generation is disabled through HID0, then all parity checking should also be disabled through HID0, and all parity pins may be left unconnected by the system. AVCC (or L2AVCC) 2.2 µF 2.2 µF GND Low ESL surface mount capacitors VCC 10 Ω |
Similar Part No. - WED3C755E8M350BC |
|
Similar Description - WED3C755E8M350BC |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |