Crystal-to-HSTL 100MHz / 200MHz PCI Express™ Clock Synthesizer ICS842S104 DATA SHEET General Description Features The ICS842S104 is a PLL-based clock generator specifically designed for PCI Express™ Clock Generation 2 applications. This device generates either a 200MHz or 100MHz differential HSTL clock from an input reference of 25MHz. The input reference may be derived from an external source or by the addition of a 25MHz crystal to the on-chip crystal oscillator. An external reference is applied to the XTAL_IN pin with the XTAL_OUT pin left floating.The device offers spread spectrum clock output for reduced EMI applications. An I2C bus interface is used to enable or disable spread spectrum operation as well as select either a down spread value of -0.35% or -0.5%.The ICS842S104 is available in a lead-free 24-Lead package. • • • • • • • • • • • Four differential HSTL output pairs Crystal oscillator interface: 25MHz Output frequency: 100MHz or 200MHz RMS phase jitter @ 200MHz (12kHz – 20MHz): 1.27ps (typical) Cycle-to-cycle jitter: 25ps (maximum) I2C support with readback capabilities up to 400kHz Spread Spectrum for electromagnetic interference (EMI) reduction 3.3V core/1.5V to 2.0V output operating supply 0°C to 70°C ambient operating temperature Available lead-free (RoHS 6) package PCI Express Gen2 Jitter Compliant HiPerClockS™ Block Diagram XTAL_IN Pin Assignment 25MHz OSC PLL XTAL_OUT SDATA Pullup SCLK Pullup Divider Network 4 4 SRCT[1:4] SRCC[1:4] I2 C Logic SRCT3 SRCC3 VSS VDDO SRCT2 SRCC2 SRCT1 SRCC1 VSS VDD VSS nc 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 SRCC4 SRCT4 VDDO SDATA SCLK XTAL_OUT XTAL_IN VDD VSS nc VDDA VSS ICS842S104 24-Lead TSSOP 4.4mm x 7.8mm x 0.925mm package body G Package Top View ICS842S104CG REVISION A MARCH 17, 2010 1 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Table 1. Pin Descriptions Number Name Type Description 1, 2 SRCT3, SRCC3 Output Differential output pair. HSTL interface levels. 3, 9, 11, 13, 16 VSS Power Power supply ground. 4, 22 VDDO Power Output power supply pins. 5, 6 SRCT2, SRCC2 Output Differential output pair. HSTL interface levels. 7, 8 SRCT1, SRCC1 Output Differential output pair. HSTL interface levels. 10, 17 VDD Power Core supply pins. 12, 15 nc Unused No connect. 14 VDDA Power Analog supply for PLL. 18, 19 XTAL_IN, XTAL_OUT Input Crystal oscillator interface. XTAL_IN is the input. XTAL_OUT is the output. 20 SCLK Input Pullup I2C compatible SCLK. This pin has an internal pullup resistor. LVCMOS/LVTTL interface levels. 21 SDATA I/O Pullup I2C compatible SDATA. This pin has an internal pullup resistor. LVCMOS/LVTTL interface levels. 23, 24 SRCT4, SRCC4 Output Differential output pair. HSTL interface levels. NOTE: Pullup refers to internal input resistors. See Table 2, Pin Characteristics, for typical values. Table 2. Pin Characteristics Symbol Parameter CIN Input Capacitance 2 pF RPULLUP Input Pullup Resistor 51 kΩ ICS842S104CG REVISION A MARCH 17, 2010 Test Conditions 2 Minimum Typical Maximum Units ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Serial Data Interface To enhance the flexibility and function of the clock synthesizer, a two-signal I2C 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 interface initialize 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. Data Protocol The clock driver serial protocol accepts byte write, byte read, block write and block read 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 3A. The block write and block read protocol is outlined in Table 3B, while Table 3C outlines the corresponding byte write and byte read protocol. The slave receiver address is 11010010 (D2h). Table 3A.Command Code Definition Bit 7 Description 0 = Block read or block write operation, 1 = Byte read or byte write operation. 6:5 Chip select address, set to “00” to access device. 4:0 Byte offset for byte read or byte write operation. For block read or block write operations, these bits must be “00000”. ICS842S104CG REVISION A MARCH 17, 2010 3 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Table 3B. Block Read and Block Write Protocol Bit 1 2:8 Description = Block Write Start Slave address - 7 bits Bit Description = Block Read 1 Start 2:8 Slave address - 7 bits 9 Write 9 Write 10 Acknowledge from slave 10 Acknowledge from slave 11:18 Command Code - 8 bits 11:18 Command Code - 8 bits 19 20:27 28 29:36 37 38:45 46 Acknowledge from slave 19 Acknowledge from slave Byte Count - 8 bits 20 Repeat start Acknowledge from slave Data byte 1 - 8 bits Acknowledge from slave Data byte 2 - 8 bits Acknowledge from slave Data Byte/Slave Acknowledges Data Byte N - 8 bits Acknowledge from slave Stop 21:27 Slave address - 7 bits 28 Read = 1 29 Acknowledge from slave 30:37 Byte Count from slave - 8 bits 38 Acknowledge 39:46 Data Byte 1 from slave - 8 bits 47 Acknowledge 48:55 Data Byte 2 from slave - 8 bits 56 Acknowledge Data Bytes from Slave/Acknowledge Data Byte N from slave - 8 bits Not Acknowledge Table 3C. Byte Read and Byte Write Protocol Bit 1 2:8 Description = Byte Write Start Slave address - 7 bits Bit Description = Byte Read 1 Start 2:8 Slave address - 7 bits 9 Write 9 Write 10 Acknowledge from slave 10 Acknowledge from slave 11:18 Command Code - 8 bits 11:18 Command Code - 8 bits 19 20:27 Acknowledge from slave 19 Acknowledge from slave Data Byte - 8 bits 20 Repeat start 28 Acknowledge from slave 29 Stop ICS842S104CG REVISION A MARCH 17, 2010 21:27 Slave address - 7 bits 28 Read 29 Acknowledge from slave 30:37 Data from slave - 8 bits 38 Not Acknowledge 39 Stop 4 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Control Registers Table 3G. Byte 3:Control Register 3 Table 3D. Byte 0: Control Register 0 Bit @Pup Name 7 0 Reserved 6 1 5 1 Description Bit @Pup Name Description Reserved 7 1 Reserved Reserved SRC[T/C]4 Output Enable 0 = Disable (Hi-Z) 1 = Enable 6 0 Reserved Reserved SRC[T/C]4 5 1 Reserved Reserved 4 0 Reserved Reserved SRC[T/C]3 SRC[T/C]3 Output Enable 0 = Disable (Hi-Z) 1 = Enable 3 1 Reserved Reserved 2 1 Reserved Reserved 1 1 Reserved Reserved 0 1 Reserved Reserved 4 1 SRC[T/C]2 SRC[T/C]2 Output Enable 0 = Disable (Hi-Z) 1 = Enable 3 1 SRC[T/C]1 SRC[T/C]1 Output Enable 0 = Disable (Hi-Z) 1 = Enable 2 1 Reserved Reserved 1 0 Reserved Reserved 0 0 Reserved Reserved Table 3H. Byte 4: Control Register 4 Table 3E. Byte 1: Control Register 1 Bit @Pup Name Description 7 0 Reserved Reserved 6 0 Reserved Reserved 5 0 Reserved Reserved 4 0 Reserved Reserved 3 0 Reserved Reserved Bit @Pup Name Description 2 0 Reserved Reserved 7 0 Reserved Reserved 1 0 Reserved Reserved 6 0 Reserved Reserved 0 1 Reserved Reserved 5 0 Reserved Reserved 4 0 Reserved Reserved 3 0 Reserved Reserved 2 0 Reserved Reserved 1 0 Reserved Reserved 0 0 Reserved Reserved Table 3I. Byte 5: Control Register 5 Bit @Pup Name Description 7 0 Reserved Reserved 6 0 Reserved Reserved 5 0 Reserved Reserved 4 0 Reserved Reserved 3 0 Reserved Reserved Description 2 0 Reserved Reserved 1 0 Reserved Reserved 0 0 Reserved Reserved Table 3F. Byte 2: Control Register 2 Bit @Pup Name 7 1 SRCT/C Spread Spectrum Selection 0 = -0.35%, 1 = -0.5% 6 1 Reserved Reserved 5 1 Reserved Reserved 4 0 Reserved Reserved 3 1 Reserved Reserved SRC Spread Spectrum Enable 0 = Spread Off, 1 = Spread On 2 0 SRC 1 1 Reserved Reserved 0 1 FOUTCTL Output Frequency Control 0 = 100MHz 1 = 200MHz ICS842S104CG REVISION A MARCH 17, 2010 5 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Table 3J. Byte 6: Control Register 6 Bit @Pup Name 7 0 TEST_SEL Table 3K. Byte 7: Control Register 7 Description Bit @Pup Name Description REF/N or Hi-Z Select 0 = Hi-Z, 1 = REF/N 7 0 Revision Code Bit 3 6 0 Revision Code Bit 2 TEST Clock Mode Entry Control 0 = Normal Operation, 1 = REF/N or Hi-Z Mode 5 0 Revision Code Bit 1 4 0 Revision Code Bit 0 6 0 TEST_MODE 3 0 Vendor ID Bit 3 5 0 Reserved Reserved 2 0 Vendor ID Bit 2 4 1 Reserved Reserved 1 0 Vendor ID Bit 1 3 0 Reserved Reserved 0 1 Vendor ID Bit 0 2 0 Reserved Reserved 1 1 Reserved Reserved 0 1 Reserved Reserved ICS842S104CG REVISION A MARCH 17, 2010 6 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Absolute Maximum Ratings NOTE: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These ratings are stress specifications only. Functional operation of product at these conditions or any conditions beyond those listed in the DC Characteristics or AC Characteristics is not implied. Exposure to absolute maximum rating conditions for extended periods may affect product reliability. Item Rating Supply Voltage, VDD 4.6V Inputs, VI XTAL_IN Other Inputs 0V to VDD -0.5V to VDD + 0.5V Outputs, IO Continuous Current Surge Current 50mA 100mA Package Thermal Impedance, θJA 77.5°C/W (0 mps) Storage Temperature, TSTG -65°C to 150°C DC Electrical Characteristics Table 4A. Power Supply DC Characteristics, VDD = 3.3V ± 5%, VDDO = 1.5V to 2.0V, TA = 0°C to 70°C Symbol Parameter VDD Test Conditions Minimum Typical Maximum Units Positive Supply Voltage 3.135 3.3 3.465 V VDDA Analog Supply Voltage VDD – 0.21 3.3 VDD V VDDO Output Supply Voltage 1.5 2.0 V IDD Power Supply Current 106 mA IDDA Analog Supply Current 21 mA IDDO Output Supply Current 7 mA Table 4B. LVCMOS/LVTTL DC Characteristics, VDD = 3.3V ± 5%, TA = 0°C to 70°C Symbol Parameter Test Conditions VIH Input High Voltage VIL Input Low Voltage IIH Input High Current SDATA, SCLK VDD = VIN = 3.465V IIL Input Low Current SDATA, SCLK VDD = 3.465V, VIN = 0V Minimum Typical Maximum Units 2 VDD + 0.3 V -0.3 0.8 V 10 µA -150 µA Table 4C. HSTL DC Characteristics, VDD = 3.3V ± 5%, VDDO = 1.5V to 2.0V, TA = 0°C to 70°C Symbol Parameter VOH Output High Voltage; NOTE 1 VOL Output Low Voltage; NOTE 1 VOX Output Crossover Voltage; NOTE 2 VSWING Peak-to-Peak Output Voltage Swing Test Conditions Minimum Typical Maximum Units 0.9 1.2 V 0 0.4 V 40% x (VOH - VOL) + VOL 65% x (VOH - VOL) + VOL % 0.6 1.1 V NOTE 1: Outputs terminated with 50Ω to GND. NOTE 2: Defined with respect to output voltage swing at a given condition. ICS842S104CG REVISION A MARCH 17, 2010 7 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Table 5. Crystal Characteristics Parameter Test Conditions Minimum Mode of Oscillation Typical Maximum Units Fundamental Frequency 25 MHz Equivalent Series Resistance (ESR) 50 Ω Shunt Capacitance 7 pF NOTE: Characterized using an 18pF parallel resonant crystal. AC Electrical Characteristics Table 6. AC Characteristics, VDD = 3.3V ± 5%, TA = 0°C to 70°C Symbol Parameter fMAX Output Frequency fref Reference frequency Test Conditions Minimum Typical FOUTCTL = 0 100 FOUTCTL = 1 200 Maximum Units MHz 25 MHz 0.95 ps 0.31 ps ƒ = 200MHz, 25MHz crystal input tREFCLK_HF_RMS Phase Jitter RMS; NOTE 1, 2 High Band: 1.5MHz - Nyquist (clock frequency/2) tREFCLK_LF_RMS Phase Jitter RMS; NOTE 1 ƒ = 200MHz, 25MHz crystal input Low Band: 10kHz - 1.5MHz tsk(o) Output Skew; NOTE 2, 3 tjit(Ø) Phase Jitter, RMS (Random) tjit(cc) Cycle-to-Cycle Jitter tL PLL Lock Time odc Output Duty Cycle 50 200MHz, Integration Range: 12kHz – 20MHz 1.27 PLL Mode 48 ps ps 25 ps 60 ms 52 % NOTE: Electrical parameters are guaranteed over the specified ambient operating temperature range, which is established when the device is mounted in a test socket with maintained transverse airflow greater than 500 lfpm. The device will meet specifications after thermal equilibrium has been reached under these conditions. NOTE 1: RMS jitter after applying the two evaluation bands to the two transfer functions defined in the Common Clock Architecture and reporting the worst case results for each evaluation band. Maximum limit for PCI Express Generation 2 is 3.1ps rms for tREFCLK_HF_RMS (High Band) and 3.0 ps RMS for tREFCLK_LF_RMS (Low Band). See IDT Application Note PCI Express Reference Clock Requirements and also the PCI Express Application section of this datasheet which show each individual transfer function and the overall composite transfer function. NOTE 2: This parameter is defined in accordance with JEDEC Standard 65. NOTE 3: Defined as skew between outputs at the same supply voltage and with equal load conditions. ICS842S104CG REVISION A MARCH 17, 2010 8 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Noise Power dBc Hz Typical Phase Noise at 200MHz Offset Frequency (Hz) ICS842S104CG REVISION A MARCH 17, 2010 9 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Parameter Measurement Information 3.3V±5% 1.5V to 2.0V Phase Noise Plot VDD VDDO Qx Noise Power 3.3V±5% SCOPE VDDA Phase Noise Mask HSTL f1 nQx GND Offset Frequency f2 RMS Jitter = Area Under the Masked Phase Noise Plot 0V 3.3V HSTL Output Load AC Test Circuit RMS Phase Jitter SRCC(1:4) SRCC(1:4) SRCT(1:4) SRCT(1:4) t PW t ➤ tcycle n ➤ tcycle n+1 ➤ ➤ tjit(cc) = |tcycle n – tcycle n+1| 1000 Cycles odc = PERIOD t PW x 100% t PERIOD Cycle-to-Cycle Jitter ICS842S104CG REVISION A MARCH 17, 2010 Output Duty Cycle/Pulse Width/Period 10 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Application Information Power Supply Filtering Technique As in any high speed analog circuitry, the power supply pins are vulnerable to random noise. To achieve optimum jitter performance, power supply isolation is required. The ICS842S104 provides separate power supplies to isolate any high switching noise from the outputs to the internal PLL. VDD, VDDA and VDDO should be individually connected to the power supply plane through vias, and 0.01µF bypass capacitors should be used for each pin. Figure 1 illustrates this for a generic VDD pin and also shows that VDDA requires that an additional 10Ω resistor along with a 10µF bypass capacitor be connected to the VDDA pin. 3.3V VCC .01µF 10Ω .01µF 10µF VCCA Figure 1. Power Supply Filtering Recommendations for Unused Input and Output Pins Inputs: Outputs: LVCMOS Control Pins HSTL Outputs All control pins have internal pullups; additional resistance is not required but can be added for additional protection. A 1kΩ resistor can be used. All unused HSTL outputs can be left floating. We recommend that there is no trace attached. Both sides of the differential output pair should either be left floating or terminated. ICS842S104CG REVISION A MARCH 17, 2010 11 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Crystal Input Interface The ICS842S104 has been characterized with 18pF parallel resonant crystals. The capacitor values, C1 and C2, shown in Figure 2 below were determined using a 25MHz, 18pF parallel resonant crystal and were chosen to minimize the ppm error. The optimum C1 and C2 values can be slightly adjusted for different board layouts. XTAL_IN C1 18pF X1 18pF Parallel Crystal XTAL_OUT C2 18pF Figure 2. Crystal Input Interface Overdriving the XTAL Interface The XTAL_IN input can accept a single-ended LVCMOS signal through an AC coupling capacitor. A general interface diagram is shown in Figure 3A. The XTAL_OUT pin can be left floating. The maximum amplitude of the input signal should not exceed 2V and the input edge rate can be as slow as 10ns. This configuration requires that the output impedance of the driver (Ro) plus the series resistance (Rs) equals the transmission line impedance. In addition, matched termination at the crystal input will attenuate the signal in half. This can be done in one of two ways. First, R1 and R2 in parallel should equal the transmission line impedance. For most 50Ω applications, R1 and R2 can be 100Ω. This can also be accomplished by removing R1 and making R2 50Ω. By overdriving the crystal oscillator, the device will be functional, but note, the device performance is guaranteed by using a quartz crystal. 3.3V 3.3V R1 100 Ro ~ 7 Ohm C1 Zo = 50 Ohm XTAL_IN RS 43 R2 100 Driv er_LVCMOS 0.1uF XTAL_OUT Cry stal Input Interf ace Figure 3A. General Diagram for LVCMOS Driver to XTAL Input Interface VCC=3.3V C1 Zo = 50 Ohm XTAL_IN R1 50 Zo = 50 Ohm LVPECL 0.1uF XTAL_OUT Cry stal Input Interf ace R2 50 R3 50 Figure 3B. General Diagram for LVPECL Driver to XTAL Input Interface ICS842S104CG REVISION A MARCH 17, 2010 12 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Termination for HSTL Outputs VDDO VDD Zo = 50 + Zo = 50 HSTL ICS HiPerClockS HSTL Driv er R1 50 HSTL R2 50 Figure 4. HSTL Output Termination ICS842S104CG REVISION A MARCH 17, 2010 13 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Schematic Example Figure 5 shows an example of ICS842S104 application schematic. In this example, the device is operated at VDD = 3.3V and VDDO = 1.8V. Both input options are shown. The device can either be driven using a quartz crystal or a 3.3V LVCMOS signal. The C1 and C2 = 18pF are recommended for frequency accuracy. For different board layouts, the C1 and C2 may be slightly adjusted for optimizing fequency accuracy. The LVHSTL output driver termination examples are shown in this schematic. The decoupling capacitor should be located as close as possible to the power pin. Logic Control Input Examples Set Logic Input to '1' Set Logic Input to '0' VDD VDDO + RU2 Not Install To Logic Input pins RD1 Not Install Zo = 50 Ohm To Logic Input pins 12 11 10 9 8 7 6 5 4 3 2 1 RU1 1K VDD Zo = 50 Ohm SRCT1 SRCC1 RD2 1K - R1 50 U1 nc VSS VD D VSS SR C C 1 SR C T 1 SR C C 2 SR C T 2 VD D O VSS SR C C 3 SR C T 3 VDD R2 50 VSS VD D A nc VSS VD D XTAL_IN XTAL_OU T SC LK SD ATA VD D O SR C T 4 SR C C 4 VDD=3.3V 13 14 15 16 17 18 19 20 21 22 23 24 VDDO=1.8V SRCT4 VDD VDDA C4 0.01u 10uF VDD 25MHz C2 18pF VDDO X1 C1 18pF J1 5 SDA 4 3 2 SCL 1 R8 R9 R7 SP Zo = 50 Ohm - F p 8 1 VDD R6 SP + SRCC4 C3 R4 50 SC LK SD AT A R3 10 Zo = 50 Ohm VDD VDDO (U1-10) 0 VDD C5 0.1uF 0 R5 50 (U1-17) C6 0.1uF (U1-4) VDDO C7 0.1uF (U1-22) C8 0.1uF Figure 5. ICS842S104 Schematic Example ICS842S104CG REVISION A MARCH 17, 2010 14 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER PCI Express Application Note PCI Express jitter analysis methodology models the system response to reference clock jitter. The below block diagram shows the most frequently used Common Clock Architecture in which a copy of the reference clock is provided to both ends of the PCI Express Link. In the jitter analysis, the Tx and Rx serdes PLLs are modeled as well as the phase interpolator in the receiver. These transfer functions are called H1, H2, and H3 respectively. The overall system transfer function at the receiver is: For PCI Express Gen 1, one transfer function is defined and the evaluation is performed over the entire spectrum: DC to Nyquist (e.g for a 100MHz reference clock: 0Hz to 50MHz) and the jitter result is reported in peak-peak. For PCI Express Gen 2, two transfer functions are defined with 2 evaluation ranges and the final jitter number is reported in rms. The two evaluation ranges for PCI Express Gen 2 are 10kHz - 1.5MHz (Low Band) and 1.5MHz - Nyquist (High Band). The below plots show the individual transfer functions as well as the overall transfer function Ht. The respective -3 dB pole frequencies for each transfer function are labeled as F1 for transfer function H1, F2 for H2, and F3 for H3. For a more thorough overview of PCI Express jitter analysis methodology, please refer to IDT Application Note PCI Express Reference Clock Requirements. t ( s ) = H3 ( s ) × [ H1 ( s ) – H2 ( s The jitter spectrum seen by the receiver is the result of applying this system transfer function to the clock spectrum X(s) and is: s) = X ( s ) × H3 ( s ) × [ H1 ( s ) – H2( In order to generate time domain jitter numbers, an inverse Fourier Transform is performed on X(s)*H3(s) * [H1(s) - H2(s)]. ICS842S104CG REVISION A MARCH 17, 2010 15 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Magnitude of Transfer Functions - PCIe Gen 1 0 F1: 2.2e+007 F2: 1.5e+006 F3: 1.5e+006 -10 Mag (dB) -20 -30 -40 H1 H2 H3 Ht=(H1-H2)*H3 -50 -60 3 10 4 10 5 6 7 10 10 Frequency (Hz) 10 PCIe Gen 1 Magnitude of Transfer Function Magnitude of Transfer Functions - PCIe Gen 2B Magnitude of Transfer Functions - PCIe Gen 2A 0 F1: 1.6e+007 F2: 5.0e+006 F3: 1.0e+006 -10 -10 -20 -20 Mag (dB) Mag (dB) 0 -30 -30 -40 -40 H1 H2 H3 Ht=(H1-H2)*H3 -50 -60 3 10 F1: 1.6e+007 F2: 8.0e+006 F3: 1.0e+006 4 10 5 6 10 10 Frequency (Hz) -60 3 10 7 10 PCIe Gen 2A Magnitude of Transfer Function ICS842S104CG REVISION A MARCH 17, 2010 H1 H2 H3 Ht=(H1-H2)*H3 -50 4 10 5 6 10 10 Frequency (Hz) 7 10 PCIe Gen 2B Magnitude of Transfer Function 16 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Power Considerations This section provides information on power dissipation and junction temperature for the ICS842S104. Equations and example calculations are also provided. 1. Power Dissipation. The total power dissipation for the ICS842S104 is the sum of the core power plus the power dissipated in the load(s). The following is the power dissipation for VDD = 3.3V + 5% = 3.465V, which gives worst case results. NOTE: Please refer to Section 3 for details on calculating power dissipated in the load. • The maximum current at 70°C is as follows: IDD_MAX = 101.7mA IDDA_MAX = 19.4mA • Power (core)MAX = VDD_MAX * (IDD_MAX + IDDA_MAX) = 3.465V * (101.7mA + 19.4mA) = 419.6mW • Power (outputs)MAX = 32mW/Loaded Output pair If all outputs are loaded, the total power is 4 * 32mW = 128mW Total Power_MAX (3.465V, with all outputs switching) = 419.6mW + 128mW = 547.6mW 2. Junction Temperature. Junction temperature, Tj, is the temperature at the junction of the bond wire and bond pad directly affects the reliability of the device. The maximum recommended junction temperature for HiPerClockS devices is 125°C. Limiting the internal transistor junction temperature, Tj, to 125°C ensures that the bond wire and bond pad temperature remains below 125°C. The equation for Tj is as follows: Tj = θJA * Pd_total + TA Tj = Junction Temperature θJA = Junction-to-Ambient Thermal Resistance Pd_total = Total Device Power Dissipation (example calculation is in section 1 above) TA = Ambient Temperature In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance θJA must be used. Assuming no air flow and a multi-layer board, the appropriate value is 77.5°C/W per Table 7 below. Therefore, Tj for an ambient temperature of 70°C with all outputs switching is: 70°C + 0.548W * 77.5°C/W = 112.5°C. This is below the limit of 125°C. This calculation is only an example. Tj will obviously vary depending on the number of loaded outputs, supply voltage, air flow and the type of board (multi-layer). Table 7. Thermal Resistance θJA for 24 Lead TSSOP, Forced Convection θJA by Velocity Meters per Second Multi-Layer PCB, JEDEC Standard Test Boards ICS842S104CG REVISION A MARCH 17, 2010 0 1 2.5 77.5°C/W 73.2°C/W 71.0°C/W 17 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER 3. Calculations and Equations. The purpose of this section is to calculate the power dissipation for the HSTL output pair. HSTL output driver circuit and termination are shown in Figure 6. VDDO Q1 VOUT RL 50Ω Figure 6. HSTL Driver Circuit and Termination To calculate worst case power dissipation into the load, use the following equations which assume a 50Ω load. Pd_H is power dissipation when the output drives high. Pd_L is the power dissipation when the output drives low. Pd_H = (VOH_MAX /RL) * (VDD_MAX - VOH_MAX) Pd_L = (VOL_MAX /RL) * (VDD_MAX - VOL_MAX) Pd_H = (1.2V/50Ω) * (2.0V - 1.2V) = 19.2mW Pd_L = (0.4V/50Ω) * (2.0V - 0.4V) = 12.8mW Total Power Dissipation per output pair = Pd_H + Pd_L = 32mW ICS842S104CG REVISION A MARCH 17, 2010 18 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Reliability Information Table 8. θJA vs. Air Flow Table for a 24 Lead TSSOP θJA vs. Air Flow Meters per Second Multi-Layer PCB, JEDEC Standard Test Boards 0 1 2.5 77.5°C/W 73.2°C/W 71.0°C/W Transistor Count The transistor count for ICS842S104 is: 11,891 Package Outline and Package Dimensions Package Outline - G Suffix for 24 Lead TSSOP Table 9. Package Dimensions All Dimensions in Millimeters Symbol Minimum Maximum N 24 A 1.20 A1 0.05 0.15 A2 0.80 1.05 b 0.19 0.30 c 0.09 0.20 D 7.70 7.90 E 6.40 Basic E1 4.30 4.50 e 0.65 Basic L 0.45 0.75 α 0° 8° aaa 0.10 Reference Document: JEDEC Publication 95, MO-153 ICS842S104CG REVISION A MARCH 17, 2010 19 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Ordering Information Table 10. Ordering Information Part/Order Number 842S104CGLF 842S104CGLFT Marking ICS842S104CGL ICS842S104CGL Package “Lead-Free” 24 Lead TSSOP “Lead-Free” 24 Lead TSSOP Shipping Packaging Tube 2500 Tape & Reel Temperature 0°C to 70°C 0°C to 70°C NOTE: Parts that are ordered with an "LF" suffix to the part number are the Pb-Free configuration and are RoHS compliant. While the information presented herein has been checked for both accuracy and reliability, Integrated Device Technology (IDT) assumes no responsibility for either its use or for the infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use in normal commercial applications. Any other applications, such as those requiring extended temperature ranges, high reliability or other extraordinary environmental requirements are not recommended without additional processing by IDT. IDT reserves the right to change any circuitry or specifications without notice. IDT does not authorize or warrant any IDT product for use in life support devices or critical medical instruments. ICS842S104CG REVISION A MARCH 17, 2010 20 ©2010 Integrated Device Technology, Inc. ICS842S104 Data Sheet 6024 Silver Creek Valley Road San Jose, California 95138 CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER Sales 800-345-7015 (inside USA) +408-284-8200 (outside USA) Fax: 408-284-2775 www.IDT.com/go/contactIDT Technical Support [email protected] +480-763-2056 DISCLAIMER Integrated Device Technology, Inc. (IDT) and its subsidiaries reserve the right to modify the products and/or specifications described herein at any time and at IDT’s sole discretion. All information in this document, including descriptions of product features and performance, is subject to change without notice. Performance specifications and the operating parameters of the described products are determined in the independent state and are not guaranteed to perform the same way when installed in customer products. The information contained herein is provided without representation or warranty of any kind, whether express or implied, including, but not limited to, the suitability of IDT’s products for any particular purpose, an implied warranty of merchantability, or non-infringement of the intellectual property rights of others. This document is presented only as a guide and does not convey any license under intellectual property rights of IDT or any third parties. IDT’s products are not intended for use in life support systems or similar devices where the failure or malfunction of an IDT product can be reasonably expected to significantly affect the health or safety of users. Anyone using an IDT product in such a manner does so at their own risk, absent an express, written agreement by IDT. Integrated Device Technology, IDT and the IDT logo are registered trademarks of IDT. Other trademarks and service marks used herein, including protected names, logos and designs, are the property of IDT or their respective third party owners. Copyright 2010. All rights reserved.