CY28442ZXC

ADVANCE INFORMATION CY28442 Clock Generator for Intel Alviso Chipset Features • 96/100 MHz Spreadable differential clock. • 33-MHz PCI clock • Compliant to Intel CK410M • Low-voltage frequency select input • Supports Intel Pentium-M CPU • I2C support with readback capabilities • Selectable CPU frequencies • Ideal Lexmark Spread Spectrum profile for maximum electromagnetic interference (EMI) reduction • Differential CPU clock pairs • 100-MHz differential SRC clocks • 3.3V power supply • 96-MHz differential dot clock • 56-pin TSSOP package • 48-MHz USB clocks • SRC clocks independently stoppable through CLKREQ#[A:B] CPU SRC PCI REF DOT96 USB_48 x2 / x3 x5/6 x6 x2 x2 x1 Block Diagram XIN XOUT Pin Configuration 14.318MHz Crystal PCI_STP# PLL1 CPU CPU_STP# CLKREQ[A:B]# VDD_REF REF PLL Reference Divider VDD_CPU CPUT_ITP/SRCT7 CPUC_ITP/SRCC7 FS_[C:A] VDD_SRC SRCT[1:5] CPUC[1:5] VDD_PCI PCI VDD_PCI PCIF PLL2 96MSS Divider PLL4 FIXED Divider VDD_48MHz 96_100_SSCT 96_100_SSCC VDD_48MHz DOT96T DOT96C VDD_48 USB VTTPWR_GD#/PD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 CY28442 VDD_REF VSS_REF PCI3 PCI4 PCI5 VSS_PCI VDD_PCI ITP_EN/PCIF0 **96_100_SEL/PCIF1 VTTPWRGD#/PD VDD_48 FS_A/48M_0 VSS_48 DOT96T DOT96C FS_B/TESTMODE 96_100_SSCT 96_100_SSCC SRCT1 SRCC1 VDD_SRC SRCT2 SRCC2 SRCT3 SRCC3 SRCT4_SATA SRCC4_SATA VDD_SRC IREF VDD_CPU CPUT CPUC 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 PCI2/SEL_CLKREQ** PCI_STP# CPU_STP# FS_C(TEST_SEL)/REF0 REF1 VSSA2 XIN XOUT VDDA2 SDATA SCLK VSS_CPU CPUT0 CPUC0 VDD_CPU CPUT1 CPUC1 IREF VSSA VDDA CPU2T_ITP/SRCT7 CPU2C_ITP/SRCC7 VDD_SRC_ITP CLKREQA#/SRCT6 CLKREQB#/SRCC6 SRCT5 SRCC5 VSS_SRC 56 pin TSSOP/SSOP SDATA SCLK I2C Logic Cypress Semiconductor Corporation Document #: 38-07680 Rev. ** • 3901 North First Street • San Jose, CA 95134 • 408-943-2600 Revised June 24, 2004 [+] Feedback ADVANCE INFORMATION CY28442 Pin Definitions Pin No. Name 1 VDD_REF 2 VSS_REF 33,32 CLKREQA#/SRCT6, CLKREQB#,SRCC6 7 VDD_PCI 6 3,4,5 Type Description PWR 3.3V power supply for outputs. GND Ground for outputs. I/O, PU 3.3V LVTTL input for enabling assigned SRC clock (active low) or 100 MHz Serial Reference Clock. Selectable through CLKREQA# defaults to enable/disable SRCT/C4, CLKREQB# defaults to enable/disable SRCT/C5. Assignment can be changed via SMBUS register Byte 8. PWR 3.3V power supply for outputs. VSS_PCI GND Ground for outputs. PCI O, SE 33-MHz clock 8 ITP_EN/PCIF0 I/O, SE 3.3V LVTTL input to enable SRC7 or CPU2_ITP/33 MHz clock output. (sampled on the VTT_PWRGD# assertion). 1 = CPU2_ITP, 0 = SRC7 9 PCIF1/96_100_SEL I/O, 33-MHz clock/3.3V-tolerant input for 96_100M frequency selection PD,SE (sampled on the VTT_PWRGD# assertion). 1 = 100MHz, 0 = 96MHz 10 VTT_PWRGD#/PD I, PU 3.3V LVTTL input. This pin is a level sensitive strobe used to latch the FS_A, FS_B, FS_C, and ITP_EN, 96MSS_SRC_SEL inputs, SEL_CLKREQ. After VTT_PWRGD# (active low) assertion, this pin becomes a real-time input for asserting power down (active high). PWR 3.3V power supply for outputs. 11 VDD_48 12 FS_A/48_M0 13 VSS_48 14,15 DOT96T, DOT96C 16 FS_B/TEST_MODE 17,18 96_100_SSC I/O GND 3.3V-tolerant input for CPU frequency selection/fixed 48-MHz clock output. Refer to DC Electrical Specifications table for Vil_FS and Vih_FS specifications. Ground for outputs. O, DIF Fixed 96-MHz clock output. I 3.3V-tolerant input for CPU frequency selection. Selects Ref/N or Tri-state when in test mode 0 = Tri-state, 1 = Ref/N Refer to DC Electrical Specifications table for Vil_FS and Vih_FS specifications. O,DIF Differential 96/100 MHz SS clock for flat-panel display 19,20,22,23, SRCT/C 24,25,30,31 O, DIF 100MHz Differential serial reference clocks. 21,28 VDD_SRC PWR 3.3V power supply for outputs. 34 VDD_SRC_ITP PWR 3.3V power supply for outputs. 26,27 SRC4_SATAT, SRC4_SATAC O, DIF Differential serial reference clock. Recommended output for SATA. 29 VSS_SRC 36,35 CPUT2_ITP/SRCT7, CPUC2_ITP/SRCC7 GND 37 VDDA PWR 3.3V power supply for PLL. 38 VSSA GND Ground for PLL. 39 IREF I 42 VDD_CPU PWR 44,43,41,40 CPUT/C O, DIF Differential CPU clock outputs. 45 VSS_CPU 46 SCLK I 47 SDATA I/O Document #: 38-07680 Rev. ** Ground for outputs. O, DIF Selectable differential CPU or SRC clock output. ITP_EN = 0 @ VTT_PWRGD# assertion = SRC7 ITP_EN = 1 @ VTT_PWRGD# assertion = CPU2 GND A precision resistor is attached to this pin, which is connected to the internal current reference. 3.3V power supply for outputs. Ground for outputs. SMBus-compatible SCLOCK. SMBus-compatible SDATA. Page 2 of 22 [+] Feedback ADVANCE INFORMATION CY28442 Pin Definitions (continued) Pin No. Name Type Description 48 VDDA2 PWR 49 XOUT O, SE 14.318-MHz crystal output. 50 XIN I GND 3.3V power supply for PLL2. 14.318-MHz crystal input. 51 VSSA2 52 REF1 O Ground for PLL2. Fixed 14.318 MHz clock output. 53 FS_C_TEST_SEL/ REF0 I/O 3.3V-tolerant input for CPU frequency selection/fixed 14.318 clock output. Selects test mode if pulled to greater than 1.8V when VTT_PWRGD# is asserted low. Refer to DC Electrical Specifications table for VIL_FS,VIH_FS specifications. 54 CPU_STP# I, PU 3.3V LVTTL input for CPU_STP# active low. 55 PCI_STP# I, PU 3.3V LVTTL input for PCI_STP# active low. 56 PCI2/SEL_CLKREQ I/O, PD 3.3V-tolerant input for CLKREQ pin selection/fixed 33-MHz clock output. (sampled on the VTT_PWRGD# assertion). 0= pins 32,33 function as clk request pins, 1= pins 32,33 function as SRC outputs. Frequency Select Pins (FS_A, FS_B and FS_C) Host clock frequency selection is achieved by applying the appropriate logic levels to FS_A, FS_B, FS_C inputs prior to VTT_PWRGD# assertion (as seen by the clock synthesizer). Upon VTT_PWRGD# being sampled low by the clock chip (indicating processor VTT voltage is stable), the clock chip samples the FS_A, FS_B and FS_C input values. For all logic levels of FS_A, FS_B and FS_C, VTT_PWRGD# employs a one-shot functionality in that once a valid low on VTT_PWRGD# has been sampled, all further VTT_PWRGD#, FS_A, FS_B and FS_C transitions will be ignored, except in test mode. Table 1. Frequency Select Table FS_A, FS_B and FS_C FS_C FS_B FS_A CPU SRC PCIF/PCI REF0 DOT96 USB 1 0 1 100 MHz 100 MHz 33 MHz 14.318 MHz 96 MHz 48 MHz 0 0 1 133 MHz 100 MHz 33 MHz 14.318 MHz 96 MHz 48 MHz 0 1 1 166 MHz 100 MHz 33 MHz 14.318 MHz 96 MHz 48 MHz 0 1 0 200 MHz 100 MHz 33 MHz 14.318 MHz 96 MHz 48 MHz Serial Data Interface Data Protocol 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. 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 2. The block write and block read protocol is outlined in Table 3 while Table 4 outlines the corresponding byte write and byte read protocol. The slave receiver address is 11010010 (D2h). Table 2. 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' Document #: 38-07680 Rev. ** Page 3 of 22 [+] Feedback ADVANCE INFORMATION CY28442 Table 3. Block Read and Block Write Protocol Block Write Protocol Bit 1 8:2 Description Start Write 10 18:11 19 27:20 28 36:29 37 45:38 Bit 1 Slave address – 7 bits 9 Block Read Protocol 8:2 Description Start Slave address – 7 bits 9 Write Acknowledge from slave 10 Acknowledge from slave Command Code – 8 bits 18:11 Command Code – 8 bits Acknowledge from slave 19 Acknowledge from slave Byte Count – 8 bits (Skip this step if I2C_EN bit set) 20 Repeat start 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 46 Acknowledge from slave .... Data Byte /Slave Acknowledges .... Data Byte N –8 bits .... Acknowledge from slave .... Stop 37:30 38 46:39 47 55:48 Byte Count from slave – 8 bits Acknowledge Data byte 1 from slave – 8 bits Acknowledge Data byte 2 from slave – 8 bits 56 Acknowledge .... Data bytes from slave / Acknowledge .... Data Byte N from slave – 8 bits .... NOT Acknowledge .... Stop Table 4. Byte Read and Byte Write Protocol Byte Write Protocol Bit 1 8:2 Description Start Slave address – 7 bits Byte Read Protocol Bit 1 8:2 Slave address – 7 bits 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 Document #: 38-07680 Rev. ** 9 Description Start 27:21 Write Slave address – 7 bits 28 Read 29 Acknowledge from slave 37:30 Data from slave – 8 bits 38 NOT Acknowledge 39 Stop Page 4 of 22 [+] Feedback ADVANCE INFORMATION CY28442 Control Registers Byte 0: Control Register 0 Bit 7 @Pup 1 6 1 Name CPUT2_ITP/SRCT7 CPUC2_ITP/SRCC7 SRC[T/C]6 5 1 SRC[T/C]5 4 1 SRC[T/C]4 3 1 SRC[T/C]3 2 1 SRC[T/C]2 1 1 SRC[T/C]1 0 1 RESERVED Description CPU[T/C]2_ITP/SRC[T/C]7 Output Enable 0 = Disable (Tri-state), 1 = Enable SRC[T/C]6 Output Enable 0 = Disable (Tri-state), 1 = Enable SRC[T/C]5 Output Enable 0 = Disable (Tri-state), 1 = Enable SRC[T/C]4 Output Enable 0 = Disable (Tri-state), 1 = Enable SRC[T/C]3 Output Enable 0 = Disable (Tri-state), 1 = Enable SRC[T/C]2 Output Enable 0 = Disable (Tri-state), 1 = Enable SRC[T/C]1 Output Enable 0 = Disable (Tri-state), 1 = Enable RESERVED Byte 1: Control Register 1 Bit @Pup Name Description 7 1 PCIF0 6 1 DOT_96T/C 5 1 USB_48 4 1 REF0 REF0 Output Enable 0 = Disabled, 1 = Enabled 3 1 REF1 REF1 Output Enable 0 = Disabled, 1 = Enabled 2 1 CPU[T/C]1 CPU[T/C]1 Output Enable 0 = Disable (Tri-state), 1 = Enabled 1 1 CPU[T/C]0 CPU[T/C]0 Output Enable 0 = Disable (Tri-state), 1 = Enabled 0 0 CPU PCIF0 Output Enable 0 = Disabled, 1 = Enabled DOT_96 MHz Output Enable 0 = Disable (Tri-state), 1 = Enabled USB_48 MHz Output Enable 0 = Disabled, 1 = Enabled PLL1 (CPU PLL) Spread Spectrum Enable 0 = Spread off, 1 = Spread on Byte 2: Control Register 2 Bit @Pup Name 7 1 PCI5 PCI5 Output Enable 0 = Disabled, 1 = Enabled 6 1 PCI4 PCI4 Output Enable 0 = Disabled, 1 = Enabled 5 1 PCI3 PCI3 Output Enable 0 = Disabled, 1 = Enabled 4 1 PCI2 PCI2 Output Enable 0 = Disabled, 1 = Enabled 3 1 Reserved Reserved, Set = 1 2 1 Reserved Reserved, Set = 1 1 1 Reserved 0 1 PCIF1 Document #: 38-07680 Rev. ** Description Reserved, Set = 1 PCIF1 Output Enable 0 = Disabled, 1 = Enabled Page 5 of 22 [+] Feedback ADVANCE INFORMATION CY28442 Byte 3: Control Register 3 Bit @Pup Name Description 7 0 SRC7 Allow control of SRC[T/C]7 with assertion of PCI_STP# or SW PCI_STP# 0 = Free running, 1 = Stopped with PCI_STP# 6 0 SRC6 Allow control of SRC[T/C]6 with assertion of PCI_STP# or SW PCI_STP# 0 = Free running, 1 = Stopped with PCI_STP# 5 0 SRC5 Allow control of SRC[T/C]5 with assertion of PCI_STP# or SW PCI_STP# 0 = Free running, 1 = Stopped with PCI_STP# 4 0 SRC4 Allow control of SRC[T/C]4 with assertion of PCI_STP# or SW PCI_STP# 0 = Free running, 1 = Stopped with PCI_STP# 3 0 SRC3 Allow control of SRC[T/C]3 with assertion of PCI_STP# or SW PCI_STP# 0 = Free running, 1 = Stopped with PCI_STP# 2 0 SRC2 Allow control of SRC[T/C]2 with assertion of PCI_STP# or SW PCI_STP# 0 = Free running, 1 = Stopped with PCI_STP# 1 0 SRC1 Allow control of SRC[T/C]1 with assertion of PCI_STP# or SW PCI_STP# 0 = Free running, 1 = Stopped with PCI_STP# 0 0 RESERVED RESERVED Byte 4: Control Register 4 Bit @Pup Name 7 0 96_100_SSC 96_100_SSC Drive Mode 0 = Driven in PWRDWN, 1 = Tri-state Description 6 0 DOT96T/C DOT_PWRDWN Drive Mode 0 = Driven in PWRDWN, 1 = Tri-state 5 0 RESERVED 4 0 PCIF1 Allow control of PCIF1 with assertion of SW and HW PCI_STP# 0 = Free running, 1 = Stopped with PCI_STP# 3 0 PCIF0 Allow control of PCIF0 with assertion of SW and HW PCI_STP# 0 = Free running, 1 = Stopped with PCI_STP# 2 1 CPU[T/C]2 Allow control of CPU[T/C]2 with assertion of CPU_STP# 0 = Free running, 1 = Stopped with CPU_STP# 1 1 CPU[T/C]1 Allow control of CPU[T/C]1 with assertion of CPU_STP# 0 = Free running, 1 = Stopped with CPU_STP# 0 1 CPU[T/C]0 Allow control of CPU[T/C]0 with assertion of CPU_STP# 0 = Free running, 1 = Stopped with CPU_STP# RESERVED Byte 5: Control Register 5 Bit @Pup Name 7 0 SRC[T/C] SRC[T/C] Stop Drive Mode 0 = Driven when PCI_STP# asserted,1 = Tri-state when PCI_STP# asserted 6 0 CPU[T/C]2 CPU[T/C]2 Stop Drive Mode 0 = Driven when CPU_STP# asserted,1 = Tri-state when CPU_STP# asserted 5 0 CPU[T/C]1 CPU[T/C]1 Stop Drive Mode 0 = Driven when CPU_STP# asserted,1 = Tri-state when CPU_STP# asserted 4 0 CPU[T/C]0 CPU[T/C]0 Stop Drive Mode 0 = Driven when CPU_STP# asserted,1 = Tri-state when CPU_STP# asserted 3 0 SRC[T/C][7:1] SRC[T/C] PWRDWN Drive Mode 0 = Driven when PD asserted,1 = Tri-state when PD asserted 2 0 CPU[T/C]2 CPU[T/C]2 PWRDWN Drive Mode 0 = Driven when PD asserted,1 = Tri-state when PD asserted Document #: 38-07680 Rev. ** Description Page 6 of 22 [+] Feedback ADVANCE INFORMATION CY28442 Byte 5: Control Register 5 (continued) Bit @Pup Name Description 1 0 CPU[T/C]1 CPU[T/C]1 PWRDWN Drive Mode 0 = Driven when PD asserted,1 = Tri-state when PD asserted 0 0 CPU[T/C]0 CPU[T/C]0 PWRDWN Drive Mode 0 = Driven when PD asserted,1 = Tri-state when PD asserted Byte 6: Control Register 6 Bit @Pup Name Description 7 0 TEST_SEL 6 0 TEST_MODE 5 0 RESERVED 4 1 REF 3 1 2 HW FS_C FS_C Reflects the value of the FS_C pin sampled on power up 0 = FS_C was low during VTT_PWRGD# assertion 1 HW FS_B FS_B Reflects the value of the FS_B pin sampled on power up 0 = FS_B was low during VTT_PWRGD# assertion 0 HW FS_A FS_A Reflects the value of the FS_A pin sampled on power up 0 = FS_A was low during VTT_PWRGD# assertion REF/N or Tri-state Select 0 = Tri-state, 1 = REF/N Clock Test Clock Mode Entry Control 0 = Normal operation, 1 = REF/N or Tri-state mode, RESERVED REF Output Drive Strength 0 = Low, 1 = High PCI, PCIF and SRC clock SW PCI_STP Function outputs except those set 0=SW PCI_STP assert, 1= SW PCI_STP deassert to free running When this bit is set to 0, all STOPPABLE PCI, PCIF and SRC outputs will be stopped in a synchronous manner with no short pulses. When this bit is set to 1, all STOPPED PCI, PCIF and SRC outputs will resume in a synchronous manner with no short pulses. Byte 7: Vendor ID Bit @Pup Name Description 7 0 Revision Code Bit 3 Revision Code Bit 3 6 0 Revision Code Bit 2 Revision Code Bit 2 5 0 Revision Code Bit 1 Revision Code Bit 1 4 0 Revision Code Bit 0 Revision Code Bit 0 3 1 Vendor ID Bit 3 Vendor ID Bit 3 2 0 Vendor ID Bit 2 Vendor ID Bit 2 1 0 Vendor ID Bit 1 Vendor ID Bit 1 0 0 Vendor ID Bit 0 Vendor ID Bit 0 Byte 8: Control Register 8 Bit @Pup Name Description 7 0 CLKREQ#B SRC[T/C]7CLKREQ#B control 1 = SRC[T/C]7 stoppable by CLKREQ#B pin 0 = SRC[T/C]7 not controlled by CLKREQ#B pin 6 1 CLKREQ#B SRC[T/C]5 CLKREQ#B control 1 = SRC[T/C]5 stoppable by CLKREQ#B pin 0 = SRC[T/C]5 not controlled by CLKREQ#B pin 5 0 CLKREQ#B SRC[T/C]3 CLKREQ#B control 1 = SRC[T/C]3 stoppable by CLKREQ#B pin 0 = SRC[T/C]3 not controlled by CLKREQ#B pin 4 0 CLKREQ#B SRC[T/C]1 CLKREQ#B control 1 = SRC[T/C]1 stoppable by CLKREQ#B pin 0 = SRC[T/C]1 not controlled by CLKREQ#B pin Document #: 38-07680 Rev. ** Page 7 of 22 [+] Feedback ADVANCE INFORMATION CY28442 Byte 8: Control Register 8 (continued) Bit @Pup Name Description 3 0 RESERVED RESERVED 2 1 CLKREQ#A SRC[T/C]4 CLKREQ#A control 1 = SRC[T/C]4 stoppable by CLKREQ#A pin 0 = SRC[T/C]4 not controlled by CLKREQ#A pin 1 0 CLKREQ#A SRC[T/C]2 CLKREQ#A control 1 = SRC[T/C]2 stoppable by CLKREQ#A pin 0 = SRC[T/C]2 not controlled by CLKREQ#A pin 0 0 RESERVED RESERVED Byte 9: Control Register 9 Bit @Pup Name 7 0 S3 6 0 S2 5 0 S1 4 0 S0 Description 96_100_SSC Spread Spectrum Selection table: S[3:0] SS% ‘0000’ = -0.8%(Default value) ‘0001’ = -1.0% ‘0010‘ = -1.25% ‘0011‘ = -1.5% ‘0100‘ = -1.75% ‘0101‘ = -2.0% ‘0110‘ = -2.5% ‘0111‘ = -0.5% ‘1000‘ = ± 0.25% ‘1001‘ = ± 0.4% ‘1010‘ = ± 0.5% ‘1011‘ = ± 0.6% ‘1100‘ = ± 0.8% ‘1101‘ = ± 1.0% ‘1110‘ = ± 1.25% 3 1 96_100 SEL ‘1111‘ = ± 1.5% Software select 96_100_SSC output frequency , 0 = 96MHz , 1 = 100MHz. 2 1 96_100 Enable 96_100_SSC Enable , 0 = Disable , 1 = Enable. 1 1 96_100 SS Enable 0 0 96_100 SW HW 96_100_SSC Spread spectrum enable. 0 = Disable , 1 = Enable. Select output frequency of 96_100_SSC via software or hardware 0 = Hardware, 1 = Software. Byte 10: Control Register 10 Bit @Pup Name Description 7 0 RESERVED RESERVED 6 0 CLKREQ#B SRC[T/C]4 CLKREQ#B control 1 = SRC[T/C]4 stoppable by CLKREQ#B pin 0 = SRC[T/C]4not controlled by CLKREQ#B pin 5 0 CLKREQ#B SRC[T/C]2 CLKREQ#B control 1 = SRC[T/C]2 stoppable by CLKREQ#B pin 0 = SRC[T/C]2 not controlled by CLKREQ#B pin 4 0 RESERVED RESERVED 3 0 CLKREQ#A SRC[T/C]7CLKREQ#A control 1 = SRC[T/C]7 stoppable by CLKREQ#A pin 0 = SRC[T/C]7 not controlled by CLKREQ#A pin Document #: 38-07680 Rev. ** Page 8 of 22 [+] Feedback ADVANCE INFORMATION CY28442 Byte 10: Control Register 10 (continued) Bit @Pup Name Description 2 0 CLKREQ#A SRC[T/C]5 CLKREQ#A control 1 = SRC[T/C]5 stoppable by CLKREQ#A pin 0 = SRC[T/C]5 not controlled by CLKREQ#A pin 1 0 CLKREQ#A SRC[T/C]3 CLKREQ#A control 1 = SRC[T/C]3 stoppable by CLKREQ#A pin 0 = SRC[T/C]3 not controlled by CLKREQ#A pin 0 0 CLKREQ#A SRC[T/C]1 CLKREQ#A control 1 = SRC[T/C]1 stoppable by CLKREQ#A pin 0 = SRC[T/C]1 not controlled by CLKREQ#A pin The CY28442 requires a Parallel Resonance Crystal. Substituting a series resonance crystal will cause the CY28442 to operate at the wrong frequency and violate the ppm specification. For most applications there is a 300-ppm frequency shift between series and parallel crystals due to incorrect loading. Table 5. Crystal Recommendations Frequency (Fund) Cut Loading Load Cap Drive (max.) Shunt Cap (max.) Motional (max.) Tolerance (max.) Stability (max.) Aging (max.) 14.31818 MHz AT Parallel 0.1 mW 5 pF 0.016 pF 35 ppm 30 ppm 5 ppm 20 pF Crystal Loading Crystal loading plays a critical role in achieving low ppm performance. To realize low ppm performance, the total capacitance the crystal will see must be considered to calculate the appropriate capacitive loading (CL). The following diagram shows a typical crystal configuration using the two trim capacitors. An important clarification for the following discussion is that the trim capacitors are in series with the crystal not parallel. It’s a common misconception that load capacitors are in parallel with the crystal and should be approximately equal to the load capacitance of the crystal. This is not true. Figure 1. Crystal Capacitive Clarification Calculating Load Capacitors In addition to the standard external trim capacitors, trace capacitance and pin capacitance must also be considered to correctly calculate crystal loading. As mentioned previously, the capacitance on each side of the crystal is in series with the Document #: 38-07680 Rev. ** crystal. This means the total capacitance on each side of the crystal must be twice the specified crystal load capacitance (CL). While the capacitance on each side of the crystal is in series with the crystal, trim capacitors (Ce1,Ce2) should be calculated to provide equal capacitive loading on both sides. Page 9 of 22 [+] Feedback ADVANCE INFORMATION CY28442 Clock Chip Ci2 Ci1 Pin 3 to 6p X2 X1 Cs1 Cs2 Trace 2.8pF XTAL Ce1 Ce2 Trim 33pF Figure 2. Crystal Loading Example As mentioned previously, the capacitance on each side of the crystal is in series with the crystal. This mean the total capacitance on each side of the crystal must be twice the specified load capacitance (CL). While the capacitance on each side of the crystal is in series with the crystal, trim capacitors (Ce1,Ce2) should be calculated to provide equal capacitance loading on both sides. Use the following formulas to calculate the trim capacitor values for Ce1 and Ce2. Ce = 2 * CL – (Cs + Ci) = 1 ( Ce1 + Cs1 + Ci1 + Document #: 38-07680 Rev. ** 1 Ce2 + Cs2 + Ci2 Ce ..................................................... External trim capacitors Cs ..............................................Stray capacitance (terraced) Ci .......................................................... Internal capacitance (lead frame, bond wires etc.) CL ....................................................Crystal load capacitance Ce ..................................................... External trim capacitors Total Capacitance (as seen by the crystal) CLe CLe ......................................... Actual loading seen by crystal using standard value trim capacitors CLe ......................................... Actual loading seen by crystal using standard value trim capacitors Load Capacitance (each side) 1 CL ....................................................Crystal load capacitance ) Cs ..............................................Stray capacitance (terraced) Ci .......................................................... Internal capacitance (lead frame, bond wires etc.) Page 10 of 22 [+] Feedback ADVANCE INFORMATION CLK_REQ[0:1]# Description The CLKREQ#[A:B] signals are active low input used for clean enabling and disabling selected SRC outputs. The outputs controlled by CLKREQ#[A:B] are determined by the settings in register byte 8. The CLKREQ# signal is a de-bounced signal CY28442 in that it’s state must remain unchanged during two consecutive rising edges of SRCC to be recognized as a valid assertion or de-assertion. (The assertion and de-assertion of this signal is absolutely asynchronous). CLKREQ#X SRCT(free running) SRCC(free running) SRCT(stoppable) SRCT(stoppable) Figure 3. CLK_REQ#[A:B] Deassertion/Assertion Waveform CLK_REQ[A:B]# Assertion (CLKREQ# -> LOW) PD (Power-down) – Assertion All differential outputs that were stopped are to resume normal operation in a glitch free manner. The maximum latency from the assertion to active outputs is between 2-6 SRC clock periods (2 clocks are shown) with all SRC outputs resuming simultaneously. All stopped SRC outputs must be driven high within 10 ns of CLKREQ#[1:0] de-assertion to a voltage greater than 200mV. When PD is sampled high by two consecutive rising edges of CPUC, all single-ended outputs will be held low on their next high to low transition and differential clocks must held high or Tri-stated (depending on the state of the control register drive mode bit) on the next diff clock# high to low transition within 4 clock periods. When the SMBus PD drive mode bit corresponding to the differential (CPU, SRC, and DOT) clock output of interest is programmed to ‘0’, the clock output are held with “Diff clock” pin driven high at 2 x Iref, and “Diff clock#” tristate. If the control register PD drive mode bit corresponding to the output of interest is programmed to “1”, then both the “Diff clock” and the “Diff clock#” are tristate. Note the example below shows CPUT = 133 MHz and PD drive mode = ‘1’ for all differential outputs. This diagram and description is applicable to valid CPU frequencies 100,133,166,200,266,333 and 400MHz. In the event that PD mode is desired as the initial power-on state, PD must be asserted high in less than 10 uS after asserting Vtt_PwrGd#. CLK_REQ[A:B]# Deassertion (CLKREQ# -> HIGH) The impact of deasserting the CLKREQ#[A:B] pins is all SRC outputs that are set in the control registers to stoppable via deassertion of CLKREQ#[A:B] are to be stopped after their next transition. The final state of all stopped DIF signals is low, both SRCT clock and SRCC clock outputs will not be driven. PD (Power-down) Clarification The VTT_PWRGD# /PD pin is a dual function pin. During initial power up, the pin functions as VTT_PWRGD#. Once VTT_PWRGD# has been sampled low by the clock chip, the pin assumes PD functionality. The PD pin is an asynchronous active high input used to shut off all clocks cleanly prior to shutting off power to the device. This signal is synchronized internal to the device prior to powering down the clock synthesizer. PD is also an asynchronous input for powering up the system. When PD is asserted high, all clocks need to be driven to a low value and held prior to turning off the VCOs and the crystal oscillator. Document #: 38-07680 Rev. ** Page 11 of 22 [+] Feedback ADVANCE INFORMATION CY28442 PD CPUT, 133MHz CPUC, 133MHz SRCT 100MHz SRCC 100MHz USB, 48MHz DOT96T DOT96C PCI, 33 MHz REF Figure 4. Power-down Assertion Timing Waveform PD Deassertion The power-up latency is less than 1.8 ms. This is the time from the deassertion of the PD pin or the ramping of the power supply until the time that stable clocks are output from the clock chip. All differential outputs stopped in a three-state condition resulting from power down will be driven high in less than 300 µs of PD deassertion to a voltage greater than 200 mV. After the clock chip’s internal PLL is powered up and locked, all outputs will be enabled within a few clock cycles of each other. Below is an example showing the relationship of clocks coming up. Tstable 200mV Figure 7. CPU_STP# Deassertion Waveform 1.8mS CPU_STOP# PD CPUT(Free Running CPUC(Free Running CPUT(Stoppable) CPUC(Stoppable) DOT96T DOT96C Figure 8. CPU_STP#= Driven, CPU_PD = Driven, DOT_PD = Driven Document #: 38-07680 Rev. ** Page 13 of 22 [+] Feedback ADVANCE INFORMATION CY28442 1.8mS CPU_STOP# PD CPUT(Free Running) CPUC(Free Running) CPUT(Stoppable) CPUC(Stoppable) DOT96T DOT96C Figure 9. CPU_STP# = Tri-state, CPU_PD = Tri-state, DOT_PD = Tri-state PCI_STP# Assertion The PCI_STP# signal is an active LOW input used for synchronous stopping and starting the PCI outputs while the rest of the clock generator continues to function. The set-up PCI_STP# time for capturing PCI_STP# going LOW is 10 ns (tSU). (See Figure 10.) The PCIF clocks will not be affected by this pin if their corresponding control bit in the SMBus register is set to allow them to be free running. Tsu PCI_F PCI SRC 100MHz Figure 10. PCI_STP# Assertion Waveform PCI_STP# Deassertion The deassertion of the PCI_STP# signal will cause all PCI and stoppable PCIF clocks to resume running in a synchronous manner within two PCI clock periods after PCI_STP# transitions to a high level. Tsu Tdrive_SRC PCI_STP# PCI_F PCI SRC 100MHz Figure 11. PCI_STP# Deassertion Waveform Document #: 38-07680 Rev. ** Page 14 of 22 [+] Feedback ADVANCE INFORMATION CY28442 FS_A, FS_B,FS_C VTT_PW RGD# PW RGD_VRM 0.2-0.3mS Delay VDD Clock Gen State 0 Clock State W ait for VTT_PW RGD# State 1 State 2 Off Clock Outputs State 3 On On Off Clock VCO Device is not affected, VTT_PW RGD# is ignored Sample Sels Figure 12. VTT_PWRGD# Timing Diagram S2 S1 Delay >0.25mS VTT_PWRGD# = Low Sample Inputs straps VDD_A = 2.0V Wait for