CY28353-2 Differential Clock Buffer/Driver Features Description • Phase-locked loop (PLL) clock distribution for double data rate synchronous DRAM applications This PLL clock buffer is designed for 2.5 VDD and 2.5 AVDD operation and differential data input and output levels. • Distributes one differential clock input to six differential outputs This device is a zero delay buffer that distributes a differential clock input pair (CLKINT, CLKINC) to six differential pairs of clock outputs (CLKT[0:5], CLKC[0:5]) and one differential pair feedback clock outputs (FBOUTT, FBOUTC). The clock outputs are controlled by the input clocks (CLKINT, CLKINC) and the feedback clocks (FBINT, FBINC). • External feedback pins (FBINT, FBINC) are used to synchronize the outputs to the clock input • Conforms to the DDRI specification • Spread Aware for electromagnetic interference (EMI) reduction • 28-pin SSOP package 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 clocks (CLKINT, CLKINC) and the feedback clocks (FBINT, FBINC) to provide high-performance, low-skew, low–jitter output differential clocks. Block Diagram Pin Configuration 10 CLKT0 CLKC0 CLKT1 CLKC1 SDATA Serial Interface Logic CLKT2 CLKC2 CLKT3 CLKC3 CLKT4 CLKC4 CLKINT CLKINC FBINC FBINT AVDD PLL CLKT5 CLKC5 FBOUTT FBOUTC CLKC1 GND SCLK CLKINT CLKINC AVDD AGND VDD CLKT2 CLKC2 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 CY28353-2 SCLK CLKC0 CLKT0 VDD CLKT1 GND CLKC5 CLKT5 CLKC4 CLKT4 VDD SDATA FBINC FBINT FBOUTT FBOUTC CLKT3 CLKC3 GND 28 pin SSOP .......................... Document #: 38-07372 Rev. *B Page 1 of 9 400 West Cesar Chavez, Austin, TX 78701 1+(512) 416-8500 1+(512) 416-9669 www.silabs.com CY28353-2 Pin Description [1] Pin Number Pin Name I/O Pin Description Electrical Characteristics 8 CLKINT I Complementary Clock Input. 9 CLKINC I Complementary Clock Input. LV Differential Input 21 FBINC I Feedback Clock Input. Connect to FBOUTC for accessing the PLL. 20 FBINT I Feedback Clock Input. Connect to FBOUTT for accessing the PLL. Differential Input 2,4,13,17,24,26 CLKT(0:5) O Clock Outputs. 1,5,14,16,25,27 CLKC(0:5) O Clock Outputs. Differential Outputs 19 FBOUTT O Feedback Clock Output. Connect to Differential Output FBINT for normal operation. A bypass delay capacitor at this output will control Input Reference/Output Clocks phase relationships. 18 FBOUTC O Feedback Clock Output. Connect to FBINC for normal operation. A bypass delay capacitor at this output will control Input Reference/Output Clocks phase relationships. 7 SCLK 22 SDATA I, PU Serial Clock Input. Clocks data at SDATA into the internal register. I/O, PU Data Input for the two-line serial bus Serial Data Input. Input data is clocked Data Input and Output for the to the internal register to enable/disable two-line serial bus individual outputs. This provides flexibility in power management. 3,12,23 VDD 2.5V Power Supply for Logic. 2.5V Nominal 10 AVDD 2.5V Power Supply for PLL. 2.5V Nominal 6,15,28 GND Ground. 11 AGND Analog Ground for PLL. Function Table Inputs VDDA Outputs CLKT(0:5)[2] CLKC(0:5)[2] H L L H H L L H < 20 MHz Hi-Z CLKINT CLKINC GND L GND H 2.5V L 2.5V H 2.5V < 20 MHz PLL FBOUTT FBOUTC H L H BYPASSED/OFF L H L BYPASSED/OFF H L H On L H L On Hi-Z Hi-Z Hi-Z Off Notes: 1. A bypass capacitor (0.1 F) should be placed as close as possible to each positive power pin (< 0.2”). If these bypass capacitors are not close to the pins their high-frequency filtering characteristic will be cancelled by the lead inductance of the traces. 2. Each output pair can be three-stated via the two-line serial interface. ..........................Document #: 38-07372 Rev. *B Page 2 of 9 CY28353-2 Zero Delay Buffer Serial Data Interface When used as a zero delay buffer the CY28353-2 will likely be in a nested clock tree application. For these applications the CY28353-2 offers a differential clock input pair as a PLL reference. The CY28353-2 then can lock onto the reference and translate with near zero delay to low skew outputs. For normal operation, the external feedback input, FBINT, is connected to the feedback output, FBOUTT. 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. To enhance the flexibility and function of the clock synthesizer, a two-signal serial interface is provided. Through the Serial Data Interface, various device functions, such as individual clock output buffers, can be individually enabled or disabled. The registers associated with the Serial Data Interface initializes to their default setting upon power-up, and therefore use of this interface is optional. Clock device register changes are normally made upon system initialization, if any are required. The interface cannot be used during system operation for power management functions. 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 CY28353-2 allows the user to implement unique power management schemes into the design. Outputs are tri-stated when disabled through the two-line interface as individual bits are set low in Byte0 and Byte1 registers. The feedback output pair (FBOUTT, FBOUTC) 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. Data Protocol The clock driver serial protocol accepts byte write, byte read, block write, and block r\ead operations from the controller. For block write/read operation, the bytes must be accessed in sequential order from lowest to highest byte (most significant bit first) with the ability to stop after any complete byte has been transferred. For byte write and byte read operations, the system controller can access individually indexed bytes. The offset of the indexed byte is encoded in the command code, as described in Table 1. The block write and block read protocol is outlined in Table 2 while Table 3 outlines the corresponding byte write and byte read protocol. The slave receiver address is 11010010 (D2h). Table 1. Command Code Definition Bit 7 (6:0) Description 0 = Block read or block write operation, 1 = Byte read or byte write operation Byte offset for byte read or byte write operation. For block read or block write operations, these bits should be '0000000' Table 2. Block Read and Block Write Protocol Block Write Protocol Bit 1 8:2 9 Description Start Slave address – 7 bits Write Block Read Protocol Bit 1 8:2 9 Description Start Slave address – 7 bits Write 10 Acknowledge from slave 10 Acknowledge from slave 18:11 Command Code – 8 Bits 18:11 Command Code – 8 Bits 19 Acknowledge from slave 19 Acknowledge from slave Byte Count – 8 bits (Skip this step if I2C_EN bit set) 20 Repeat start 27:20 28 36:29 37 45:38 46 Acknowledge from slave 27:21 Slave address – 7 bits Data byte 1 – 8 bits 28 Read = 1 Acknowledge from slave 29 Acknowledge from slave Data byte 2 – 8 bits Acknowledge from slave .... Data Byte /Slave Acknowledges .... Data Byte N –8 bits .... Acknowledge from slave .... Stop ..........................Document #: 38-07372 Rev. *B Page 3 of 9 37:30 38 46:39 47 55:48 56 Byte Count from slave – 8 bits Acknowledge Data byte 1 from slave – 8 bits Acknowledge Data byte 2 from slave – 8 bits Acknowledge CY28353-2 Table 2. Block Read and Block Write Protocol (continued) Block Write Protocol Bit Block Read Protocol Description Bit Description .... Data bytes from slave / Acknowledge .... Data Byte N from slave – 8 bits .... NOT Acknowledge ... Stop Table 3. Byte Read and Byte Write Protocol Byte Write Protocol Bit 1 8:2 Byte Read Protocol Description Bit Start 1 Slave address – 7 bits 8:2 Description Start Slave address – 7 bits 9 Write 9 Write 10 Acknowledge from slave 10 Acknowledge from slave 18:11 Command Code – 8 bits 18:11 Command Code – 8 bits Acknowledge from slave 19 Acknowledge from slave Data byte – 8 bits 20 Repeated start 19 27:20 28 Acknowledge from slave 29 Stop 27:21 28 Slave address – 7 bits Read 29 Acknowledge from slave 37:30 Data from slave – 8 bits 38 NOT Acknowledge 39 Stop Byte0: Output Register (1 = Enable, 0 = Disable) Bit @Pup Pin# 7 1 2, 1 Description 6 1 4, 5 5 1 – Reserved 4 1 – Reserved 3 1 13, 14 2 1 26, 27 1 1 – 0 1 24, 25 CLKT0, CLKC0 CLKT1, CLKC1 CLKT2, CLKC2 CLKT5, CLKC5 Reserved CLKT4, CLKC4 Byte1: Output Register (1 = Enable, 0 = Disable) Bit @Pup Pin# 7 1 – 6 1 17, 16 5 0 – Reserved 4 0 – Reserved 3 0 – Reserved 2 0 – Reserved 1 0 – Reserved 0 0 – Reserved ..........................Document #: 38-07372 Rev. *B Page 4 of 9 Description Reserved CLKT3, CLKC3 CY28353-2 Byte2: Test Register 3 Bit @Pup Pin# 7 1 – 0 = PLL leakage test, 1 = disable test 6 1 – Reserved 5 1 – Reserved 4 1 – Reserved 3 1 – Reserved 2 1 – Reserved 1 1 – Reserved 0 1 – Reserved Maximum Ratings[3] Description Storage Temperature: ................................. –65°C to +150°C This device contains circuitry to protect the inputs against damage due to high static voltages or electric field; however, precautions should be taken to avoid application of any voltage higher than the maximum rated voltages to this circuit. For proper operation, VIN and VOUT should be constrained to the range: Operating Temperature:.................................... 0°C to +85°C VSS < (VIN or VOUT) < VDD. Maximum Power Supply: ................................................ 3.5V Unused inputs must always be tied to an appropriate logic voltage level (either VSS or VDD). Input Voltage Relative to VSS:...............................VSS – 0.3V Input Voltage Relative to VDDQ or AVDD: ............. VDD + 0.3V DC Parameters VDDA = VDDQ = 2.5V + 5%, TA = 0C to +70C[4] Parameter Description Condition Min. VIL Input Low Voltage VIH Input High Voltage VID Differential Input Voltage[5] CLKINT, FBINT 0.35 VIX Differential Input Crossing Voltage[6] CLKINT, FBINT (VDDQ/2) – 0.2 IIN Input Current VIN = 0V or VIN = VDDQ, CLKINT, FBINT Typ. SDATA, SCLK Max. 1.0 2.2 Unit V V VDDQ/2 –10 VDDQ + 0.6 V (VDDQ/2) + 0.2 V 10 A IOL Output Low Current VDDQ = 2.375V, VOUT = 1.2V 26 35 mA IOH Output High Current VDDQ = 2.375V, VOUT=1V –18 –32 mA VOL Output Low Voltage VDDQ = 2.375V, IOL = 12 mA VOH Output High Voltage VDDQ = 2.375V, IOH = –12 mA VOUT Output Voltage Swing[7] Output Crossing Voltage[8] IOZ High-impedance Output VO = GND or VO = VDDQ Current IDSTAT Dynamic Supply Current[9] (VDDQ/2) – 0.2 All VDDQ and VDDI, FO = 170 MHz VDDQ – 0.4 V (VDDQ/2) + 0.2 V 10 µA 300 mA 1 mA 9 12 mA 4 6 pF VDDQ/2 –10 235 Static Supply Current IDD PLL Supply Current Cin Input Pin Capacitance VDDA only ..........................Document #: 38-07372 Rev. *B Page 5 of 9 V V 1.1 VOC IDDQ 0.6 1.7 CY28353-2 AC Parameters VDD = VDDQ = 2.5V ± 5%, TA = 0°C to +70°C [10,11] Parameter Description fCLK Operating Clock Frequency tDC Input Clock Duty Cycle tlock Maximum PLL lock Time Tr / Tf tpZL, tpZH tpLZ, tpHZ tCCJ tjit(h-per) Condition Min. AVDD, VDD = 2.5V ± 0.2V 60 40 Output Clocks Slew Rate 20% to 80% of VOD 1 Output Enable Time[12](all outputs) Output Disable Time[12] (all jitter[14] Max. Unit 170 MHz 60 % 100 s 2.5 V/ns 3 outputs) Cycle to Cycle Jitter Half-period Typ. ns 3 f > 66 MHz –100 f > 66 MHz –100 ns 100 ps 100 ps tPLH Low-to-High Propagation Delay, CLKINT to CLKT[0:5] 1.5 3.5 6 ns tPHL High-to-Low Propagation Delay, CLKINT to CLKT[0:5] 1.5 3.5 6 ns 100 ps –150 150 ps –50 50 ps tSKEW Any Output to Any Output Skew[13] Error[13] tPHASE Phase tPHASEJ Phase Error Jitter f > 66MHz Notes: 3. Multiple Supplies: The voltage on any input or I/O pin cannot exceed the power pin during power-up. Power supply srquencing is NOT required. 4. Unused inputs must be held HIGH or LOW to prevent them from floating. 5. Differential input signal voltage specifies the differential voltage |VTR – VCP| required for switching, where VTR is the true input level and VCP is the complementary input level. 6. Differential cross-point input voltage is expected to track VDDQ and is the voltage at which the differential signals must be crossing. 7. For load conditions see Figure 7. 8. The value of VOC is expected to be |VTR + VCP|/2. In case of each clock directly terminated by a 120 resistor. See Figure 7. 9. All outputs switching loaded with 16 pF in 60 environment. See Figure 7. 10. Parameters are guaranteed by design and characterization. Not 100% tested in production. 11. PLL is capable of meeting the specified parameters while supporting SSC synthesizers with modulation frequency between 30 kHz and 33.3 kHz with a down spread of –0.5%. 12. Refers to transition of non-inverting output. ..........................Document #: 38-07372 Rev. *B Page 6 of 9 CY28353-2 Differential Parameter Measurement Information CLKINT CLKINC FBINT FBINC t()n+1 t()n t()n = n1=N t()n (N is large number of samples) Figure 1. Static Phase Offset CLKINT CLKINC FBINT FBINC td() t() td() td() Figure 2. Dynamic Phase Offset CLKT[0:5], FBOUTT CLKC[0:5], FBOUTC CLKT[0:5], FBOUTT CLKC[0:5], FBOUTC tsk(o) Figure 3. Output Skew Notes: 13. All differential input and output terminals are terminated with 120/16 pF, as shown in Figure 7. 14. Period Jitter and Half-period Jitter specifications are separate specifications that must be met independently of each other. ..........................Document #: 38-07372 Rev. *B Page 7 of 9 t( ) td() CY28353-2 CLKT[0:5], FBOUTT CLKC[0:5], FBOUTC tc(n) CLKT[0:5], FBOUTT CLKC[0:5], FBOUTC 1 f(o) tjit(hper) = tc(n) - 1 fo Figure 4. Period Jitter CLKT[0:5], FBOUTT CLKC[0:5], FBOUTC t(hper_N+1) t(hper_n) 1 f(o) tjit(hper) = thper(n) - 1 2x fo Figure 5. Half-Period Jitter CLKT[0:5], FBOUTT CLKC[0:5], FBOUTC t c(n) t c(n) tjit(cc) = tc(n)-tc(n+1) Figure 6. Cycle-to-Cycle Jitter T PCB M e a s u re m e n t P o in t CLKT 16 pF C L K IN C LKC T PCB M e a s u re m e n t P o in t 16 pF F B IN T FBOUTT FBOUTC F B IN C Figure 7. Differential Signal Using Direct Termination Resistor ..........................Document #: 38-07372 Rev. *B Page 8 of 9 CY28353-2 Ordering Information Part Number CY28353OC-2 CY28353OC-2T Package Type Product Flow 28-pin SSOP Commercial, 0° to 70°C 28-pin SSOP–Tape and Reel Commercial, 0° to 70°C Lead Free CY28353OXC-2 CY28353OXC-2T 28-pin SSOP Commercial, 0° to 70°C 28-pin SSOP–Tape and Reel Commercial, 0° to 70°C Package Drawing and Dimensions 28-Lead (5.3 mm) Shrunk Small Outline Package O28 The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice. Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features or parameters. 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