CY28358

CY28358 200-MHz Differential Clock Buffer/Driver Features • Up to 200 MHz operation • Phase-locked loop clock distribution for Double Data Rate Synchronous DRAM applications • Distributes one clock input to six differential outputs • External feedback pin FBIN is used to synchronize the outputs to the clock input • Conforms to the DDR1 specification • Spread Aware™ for EMI reduction • 28-pin SSOP package Description This PLL clock buffer is designed for 2.5 VDD and 2.5 AVDD operation and differential output levels. This device is a zero delay buffer that distributes a clock input CLKIN to six differential pairs of clock outputs (CLKT[0:5], CLKC[0:5]) and one feedback clock output FBOUT. The clock outputs are controlled by the input clock CLKIN and the feedback clock FBIN. The two line serial bus can set each output clock pair (CLKT[0:5], CLKC[0:5]) to the Hi-Z state. When AVDD is grounded, the PLL is turned off and bypassed for test purposes. The PLL in this device uses the input clock CLKIN and the feedback clock FBIN to provide high-performance, low-skew, low–jitter output differential clocks. Block Diagram Pin Configuration 10 SCLK SDATA Serial Interface Logic CLKT2 CLKC2 CLKT3 CLKC3 CLKIN NC AVDD AGND VDD CLKT2 CLKC2 CY28358 CLKT0 CLKC0 CLKT1 CLKC1 CLKC0 CLKT0 VDD CLKT1 CLKC1 GND SCLK CLKIN PLL FBIN CLKT4 CLKC4 CLKT5 CLKC5 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 GND CLKC5 CLKT5 CLKC4 CLKT4 VDD SDATA NC FBIN FBOUT NC CLKT3 CLKC3 GND AVDD FBOUT 28 pin SSOP Rev 1.0, November 20, 2006 2200 Laurelwood Road, Santa Clara, CA 95054 Tel:(408) 855-0555 Fax:(408) 855-0550 Page 1 of 10 www.SpectraLinear.com CY28358 Pin Description[1] Pin 8 20 2,4,13,17,24,26 1,5,14,16,25,27 19 Name CLKIN FBIN CLKT(0:5) CLKC(0:5) FBOUT I/O I I O O O Clock Input. Description Input Feedback Clock Input. Connect to FBOUT for Input accessing the PLL. Clock Outputs Clock Outputs Feedback Clock Output. Connect to FBIN for normal operation. A bypass delay capacitor at this output will control Input Reference/Output Clocks phase relationships. Output Differential Outputs Electrical Characteristics 7 22 SCLK SDATA I I/O Serial Clock Input. Clocks data at SDATA into Data Input for the two line serial bus the internal register. Serial Data Input. Input data is clocked to the internal register to enable/disable individual outputs. This provides flexibility in power management. 2.5V Power Supply for Logic 2.5V Power Supply for PLL Ground Analog Ground for PLL Not Connected Data Input and Output for the two line serial bus 3,12,23 10 6,15,28 11 9, 18, 21 VDD AVDD GND AGND NC 2.5V Nominal 2.5V Nominal Function Table Inputs VDDA GND GND 2.5V 2.5V 2.5V CLKIN L H L H < 20 MHz CLKT(0:5)[2] L H L H Hi-Z Outputs CLKC(0:5)[2] H L H L Hi-Z FBOUT L H L H Hi-Z PLL BYPASSED/OFF BYPASSED/OFF On On Off Zero Delay Buffer When used as a zero delay buffer the CY28358 will likely be in a nested clock tree application. For these applications the CY28358 offers a clock input as a PLL reference. The CY28358 then can lock onto the reference and translate with near zero delay to low-skew outputs. For normal operation, the external feedback input, FBIN, is connected to the feedback output, FBOUT. By connecting the feedback output to the feedback input the propagation delay through the device is eliminated. The PLL works to align the output edge with the input reference edge thus producing a near zero delay. The reference frequency affects the static phase offset of the PLL and thus the relative delay between the inputs and outputs. When VDDA is strapped LOW, the PLL is turned off and bypassed for test purposes. Power Management The individual output enable/disable control of the CY28358 allows the user to implement unique power management schemes into the design. Outputs are three-stated when disabled through the two-line interface as individual bits are set low in Byte0 and Byte1 registers. The feedback output FBOUT cannot be disabled via two line serial bus. The enabling and disabling of individual outputs is done in such a manner as to eliminate the possibility of partial “runt” clocks. Notes: 1. A bypass capacitor (0.1 F) should be placed as close as possible to each positive power pin ( 66 MHz f > 66 MHz f > 66 MHz 20% to 80% of VOD 60 40 1 3 3 –100 –100 1.5 1.5 3.5 3.5 200 60 100 2.5 MHz % s V/ns ns ns 100 100 6 6 100 ps ps ns ns ps ps ps –150 –50 150 50 Notes: 8. Parameters are guaranteed by design and characterization. Not 100% tested in production. 9. PLL is capable of meeting the specified parameters while supporting SSC synthesizers with modulation frequency between 30kHz and 33.3kHz with a down spread of –0.5%. 10. Refers to transition of non-inverting outpu.t 11. All differential input and output terminals are terminated with 120 /16pF as shown in Figure 7. 12. Period Jitter and Half-Period Jitter specifications are separate specifications that must be met independently of each other. Rev 1.0, November 20, 2006 Page 9 of 10 CY28358 Ordering Information Part Number Package Type Product Flow CY28358OC CY28358OCT 28-Pin SSOP 28-Pin SSOP -Tape and Reel Commercial, 0 to 70 C Commercial, 0 to 70 C Package Drawing and Dimensions 28-Lead (5.3 mm) Shrunk Small Outline Package O28 51 85079 *C While SLI has reviewed all information herein for accuracy and reliability, Spectra Linear Inc. assumes no responsibility for the use of any circuitry or for the infringement of any patents or other rights of third parties which would result from each use. This product is intended for use in normal commercial applications and is not warranted nor is it intended for use in life support, critical medical instruments, or any other application requiring extended temperature range, high reliability, or any other extraordinary environmental requirements unless pursuant to additional processing by Spectra Linear Inc., and expressed written agreement by Spectra Linear Inc. Spectra Linear Inc. reserves the right to change any circuitry or specification without notice. Rev 1.0, November 20, 2006 Page 10 of 10