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| W256 12 Output Buffer for 2 DDR and 3 SRAM DIMMS Features * One input to 12 output buffer/drivers * Supports up to 2 DDR DIMMs or 3 SDRAM DIMMS * One additional output for feedback * SMBus interface for individual output control * Low skew outputs (< 100 ps) * Supports 266 MHz and 333 MHz DDR SDRAM * Dedicated pin for power management support * Space-saving 28-pin SSOP package Functional Description The W256 is a 3.3V/2.5V buffer designed to distribute high-speed clocks in PC applications. The part has 12 outputs. Designers can configure these outputs to support 3 unbuffered standard SDRAM DIMMs and 2 DDR DIMMs. The W256 can be used in conjunction with the W250-02 or similar clock synthesizer for the VIA Pro 266 chipset. The W256 also includes an SMBus interface which can enable or disable each output clock. On power-up, all output clocks are enabled (internal pull-up). Block Diagram VDD3.5_2.5 BUF_IN DDR0T_SDRAM0 DDR0C_SDRAM1 DDR1T_SDRAM2 SDATA SCLOCK PWR_DWN# Pin Configuration[1] FBOUT SSOP Top View FBOUT *PWR_DWN# DDR0T_SDRAM0 DDR0C_SDRAM1 VDD3.3_2.5 GND DDR1T_SDRAM2 DDR1C_SDRAM3 VDD3.3_2.5 BUF_IN GND DDR2T_SDRAM4 DDR2C_SDRAM5 VDD3.3_2.5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 SEL_DDR* DDR5T_SDRAM10 DDR5C_SDRAM11 VDD3.3_2.5 GND DDR4T_SDRAM8 DDR4C_SDRAM9 VDD3.3_2.5 GND DDR3T_SDRAM6 DDR3C_SDRAM7 GND SCLK SDATA SMBus Decoding & Powerdown Control DDR1C_SDRAM3 DDR2T_SDRAM4 DDR2C_SDRAM5 DDR3T_SDRAM6 DDR3C_SDRAM7 DDR4T_SDRAM8 DDR4C_SDRAM9 DDR5T_SDRAM10 DDR5C_SDRAM11 SEL_DDR Note: 1. Internal 100K pull-up resistors present on inputs marked with *. Design should not rely solely on internal pull-up resistor to set I/O pins HIGH. Cypress Semiconductor Corporation Document #: 38-07256 Rev. *C * 3901 North First Street * San Jose, CA 95134 * 408-943-2600 Revised August 30, 2004 W256 Pin Summary Name SEL_DDR 28 Pins Description Input to configure for DDR-ONLY mode or STANDARD SDRAM mode. 1 = DDR-ONLY mode. 0 = STANDARD SDRAM mode. When SEL_DDR is pulled HIGH or configured for DDR-ONLY mode, all the buffers will be configured as DDR outputs. Connect VDD3.3_2.5 to a 2.5V power supply in DDR-ONLY mode. When SEL_DDR is pulled LOW or configured for STANDARD SDRAM output, all the buffers will be configured as STANDARD SDRAM outputs. Connect VDD3.3_2.5 to a 3.3V power supply in STANDARD SDRAM mode. SMBus clock input. SMBus data input. Reference input from chipset. 2.5V input for DDR-ONLY mode; 3.3V input for STANDARD SDRAM mode. Feedback clock for chipset. Output voltage depends on VDD3.3_2.5V. Active LOW input to enable Power Down mode; all outputs will be pulled LOW. Clock outputs. These outputs provide copies of BUF_IN. Voltage swing depends on VDD3.3_2.5 power supply. Clock outputs. These outputs provide complementary copies of BUF_IN when SEL_DDR is active. These outputs provide copies of BUF_IN when SEL_DDR is inactive. Voltage swing depends on VDD3.3_2.5 power supply. Connect to 2.5V power supply when W256 is configured for DDR-ONLY mode. Connect to 3.3V power supply, when W256 is configured for standard SDRAM mode. Ground. SCLK SDATA BUF_IN FBOUT PWR_DWN# DDR[0:5]T_SDRAM [0,2,4,6,8,10] 16 15 10 1 2 3, 7, 12, 19, 23, 27 DDR[0:5]C_SDRAM 4, 8, 13, 18, 22, 26 [1,3,5,7,9, 11] VDD3.3_2.5 5, 9, 14, 21, 25 GND 6, 11, 17, 20, 24 Document #: 38-07256 Rev. *C Page 2 of 9 W256 Serial Configuration Map * The Serial bits will be read by the clock driver in the following order: Byte 0 -- Bits 7, 6, 5, 4, 3, 2, 1, 0 Byte 1 -- Bits 7, 6, 5, 4, 3, 2, 1, 0 .- . Byte N -- Bits 7, 6, 5, 4, 3, 2, 1, 0 * Reserved and unused bits should be programmed to "0". * SMBus Address for the W256 is: Table 1. A6 1 A5 1 A4 0 A3 1 A2 0 A1 0 A0 1 R/W -- Byte 7: Outputs Active/Inactive Register (1 = Active, 0 = Inactive), Default = Active Bit Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Pin # - 19, 18 12, 13 - - 7, 8 - 3, 4 Description Reserved, drive to 0 DDR3T_SDRAM6, DDR3C_SDRAM7 DDR2T_SDRAM4, DDR2C_SDRAM5 Reserved, drive to 0 Reserved, drive to 0 DDR1T_SDRAM2, DDR1C_SDRAM3 Reserved, drive to 0 DDR0T_SDRAM0, DDR0C_SDRAM1 Default 1 1 1 1 1 1 1 1 Byte 6: Outputs Active/Inactive Register (1 = Active, 0 = Inactive), Default = Active Bit Bit 7 Bit 6 Bit 5 Bit 4 Pin # - - - 1 Description Reserved, drive to 0 Reserved, drive to 0 Reserved, drive to 0 FBOUT Default 0 0 0 1 1 1 1 1 Bit 3 27, 26 DDR5T_SDRAM10, DDR5C_SDRAM11 Bit 2 - Reserved, drive to 0 Bit 1 23, 22 DDR4T_SDRAM8, DDR4C_SDRAM9 Bit 0 - Reserved, drive to 0 Document #: 38-07256 Rev. *C Page 3 of 9 W256 Maximum Ratings Supply Voltage to Ground Potential ..................-0.5 to +7.0V DC Input Voltage (except BUF_IN) ............ -0.5V to VDD+0.5 Storage Temperature .................................. -65C to +150C Static Discharge Voltage ............................................>2000V (per MIL-STD-883, Method 3015) Operating Conditions[2] Parameter VDD3.3 VDD2.5 TA COUT CIN Supply Voltage Supply Voltage Operating Temperature (Ambient Temperature) Output Capacitance Input Capacitance Description Min. 3.135 2.375 0 6 5 Typ. Max. 3.465 2.625 70 Unit V V C pF pF Electrical Characteristics Over the Operating Range Parameter VIL VIH IIL IIH IOH IOL VOL VOH IDD IDD IDDS VOUT VOC INDC Description Input LOW Voltage Input HIGH Voltage Input LOW Current Input HIGH Current Output HIGH Current Output LOW Current Output LOW Voltage[3] Output HIGH Voltage[3] Supply (DDR-Only mode) Supply Current (DDR-Only mode) Supply Current Output Voltage Swing Output Crossing Voltage Input Clock Duty Cycle Current[3] VIN = 0V VIN = VDD VDD = 2.375V VOUT = 1V VDD = 2.375V VOUT = 1.2V IOL = 12 mA, VDD = 2.375V IOH = -12 mA, VDD = 2.375V Unloaded outputs, 133 MHz Loaded outputs, 133 MHz PWR_DWN# = 0 See Test Circuity (Refer to Figure 1) 0.7 (VDD/2) -0.1 48 VDD/2 1.7 400 500 100 VDD + 0.6 (VDD/2) +0.1 52 -18 26 -32 35 0.6 Test Conditions For all pins except SMBus 2.0 50 50 Min. Typ. Max. 0.8 Unit V V A A mA mA V V mA mA A V V % Notes: 2. Multiple Supplies: The voltage on any input or I/O pin cannot exceed the power pin during power-up. Power supply sequencing is NOT required. 3. Parameter is guaranteed by design and characterization. Not 100% tested in production. Document #: 38-07256 Rev. *C Page 4 of 9 W256 Switching Characteristics[4] Parameter - - t3 t4 t3d t4d t5 t6 t7 t8 Name Operating Frequency Duty Cycle[4,5] = t2 / t1 SDRAM Rising Edge Rate[4] SDRAM Falling Edge Rate DDR Rising Edge Rate[4] DDR Falling Edge Rate[4] Output to Output Skew[4] Output t4o Output Skew for SDRAM[2] SDRAM Buffer LLProp. Delay[4] [4] Test Conditions Measured at 1.4V for 3.3V outputs Measured at VDD/2 for 2.5V outputs. Measured between 0.4V and 2.4V Measured between 2.4V and 0.4V Measured between 20% to 80% of output (Refer to Figure 1) Measured between 20% to 80% of output (Refer to Figure 1) All outputs equally loaded All outputs equally loaded Min. 66 INDC -5% 1.0 1.0 0.5 0.5 Typ. Max. 180 INDC +5% 2.50 2.50 1.50 1.50 100 150 Unit MHz % V/ns V/ns V/ns V/ns ps ps ns ns SDRAM Buffer HH Prop. Delay[4] Input edge greater than 1 V/ns Input edge greater than 1 V/ns 5 5 10 10 Switching Waveforms Duty Cycle Timing t1 t2 All Outputs Rise/Fall Time 2.4V 0.4V t3 2.4V 0.4V t4 3.3V 0V OUTPUT Output-Output Skew OUTPUT OUTPUT t5 Notes: 4. All parameters specified with loaded outputs. 5. Duty cycle of input clock is 50%. Rising and falling edge rate is greater than 1V/ns. Document #: 38-07256 Rev. *C Page 5 of 9 W256 Switching Waveforms (continued) SDRAM Buffer HH and LL Propagation Delay 1.5V INPUT OUTPUT t6 1.5V t7 Figure 1 shows the differential clock directly terminated by a 120 resistor. VCC VCC Device Under Test Out ) ) 60 VTR RT =120 Out 60 VCP Receiver Figure 1. Differential Signal Using Direct Termination Resistor Document #: 38-07256 Rev. *C Page 6 of 9 W256 Layout Example Single Voltage +3.3V Supply or 2.5V Supply FB VDD C2 0.005 F 10 F C1 G G G G G 1G 2 3 4G 5V 6G 7 8 9V 10 11 G 12 13 14 V G 28 27 26 V 25 G 24 23 22 V 21 G 20 19 18 G 17 16 15 G G FB = Dale ILB1206 - 300 (300 @ 100 MHz) Cermaic Caps C1 = 10-22 F G = VIA to GND plane layer C2 = 0.005 F V =VIA to respective supply plane layer Note: Each supply plane or strip should have a ferrite bead and capacitors All bypass caps = 0.1 F ceramic W256 G Ordering Information Ordering Code W256H W256HT Lead Free CYW256OXC CYW256OXCT 28-pin SSOP 28-pin SSOP - Tape and Reel Commercial Commercial 28-pin SSOP 28-pin SSOP - Tape and Reel Package Type Operating Range Commercial Commercial Document #: 38-07256 Rev. *C Page 7 of 9 W256 Package Drawings and Dimension 28-Lead (5.3 mm) Shrunk Small Outline Package O28 51-85079-*C Document #: 38-07256 Rev. *C Page 8 of 9 (c) Cypress Semiconductor Corporation, 2004. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be used for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges. W256 Document History Page Document Title: W256 12 Output Buffer for 2 DDR and 3 SRAM DIMMS Document Number: 38-07256 REV. ** *A *B *C ECN NO. 110521 112153 122858 258671 Issue Date 12/04/01 03/01/02 12/19/02 See ECN Orig. of Change SZV IKA RBI RGL Description of Change Change from Spec number: 38-01083 to 38-07256 Added 333 MHz for SDRAM Added power requirements to operating conditions information. Added Lead Free Devices Document #: 38-07256 Rev. *C Page 9 of 9 |
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