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W134M/W134S
Direct RambusTM Clock Generator
Features
* Differential clock source for Direct RambusTM memory subsystem for up to 800-MHz data transfer rate * Provide synchronization flexibility: the Rambus(R) Channel can optionally be synchronous to an external system or processor clock * Power managed output allows Rambus Channel clock to be turned off to minimize power consumption for mobile applications * Works with Cypress CY2210, W133, W158, W159, W161, and W167 to support Intel(R) architecture platforms * Low-power CMOS design packaged in a 24-pin, 150-mil SSOP package
Overview
The Cypress W134M/W134S provides the differential clock signals for a Direct Rambus memory subsystem. It includes signals to synchronize the Direct Rambus Channel clock to an external system clock but can also be used in systems that do not require synchronization of the Rambus clock.
Key Specifications
Supply Voltage:...................................... VDD = 3.3V0.165V Operating Temperature: ................................... 0C to +70C Input Threshold: .................................................. 1.5V typical Maximum Input Voltage: .........................................VDD+0.5V Maximum Input Frequency: ..................................... 100 MHz Output Duty Cycle: .................................. 40/60% worst case Output Type: ............................Rambus signaling level (RSL)
Block Diagram
REFCLK MULT0:1
Pin Configuration
VDDIR REFCLK VDD GND GND PCLKM SYNCLKN GND VDD VDDIPD STOPB PWRDNB 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 S0 S1 VDD GND CLK NC CLKB GND VDD MULT0 MULT1 GND
PLL
PCLKM SYNCLKN
Phase Alignment
Output Logic
CLK CLKB
S0:1
Test Logic
STOPB
Direct Rambus is a trademark and Rambus is a registered trademark of Rambus Inc. Intel is a registered trademark of Intel Corporation.
Cypress Semiconductor Corporation
*
3901 North First Street
*
San Jose
*
CA 95134 * 408-943-2600 February 18, 2000, rev. *A
W134M/W134S
Pin Definitions
Pin Name REFCLK PCLKM Pin No. 2 6 Pin Type I I Pin Description Reference Clock Input: Reference clock input, normally supplied by a system frequency synthesizer (Cypress W133). Phase Detector Input: The phase difference between this signal and SYNCLKN is used to synchronize the Rambus Channel Clock with the system clock. Both PCLKM and SYNCLKN are provided by the Gear Ratio Logic in the memory controller. If Gear Ratio Logic is not used, this pin would be connected to Ground. Phase Detector Input: The phase difference between this signal and PCLKM is used to synchronize the Rambus Channel Clock with the system clock. Both PCLKM and SYNCLKN are provided by the Gear Ratio Logic in the memory controller. If Gear Ratio Logic is not used, this pin would be connected to Ground. Clock Output Enable: When this input is driven to active LOW, it disables the differential Rambus Channel clocks. Active LOW Power-Down: When this input is driven to active LOW, it disables the differential Rambus Channel clocks and places the W134M/W134S in power-down mode. PLL Multiplier Select: These inputs select the PLL prescaler and feedback dividers to determine the multiply ratio for the PLL for the input REFCLK.
MULT0 0 0 1 1 MULT1 0 1 1 0 W134M PLL/REFCLK 4.5 6 8 5.333 W134S PLL/REFCLK 4 6 8 5.333
SYNCLKN
7
I
STOPB PWRDNB
11 12
I I
MULT 0:1
15, 14
I
CLK, CLKB S0, S1
20, 18 24, 23
O I
Complementary Output Clock: Differential Rambus Channel clock outputs. Mode Control Input: These inputs control the operating mode of the W134M/W134S.
S0 0 0 1 1 S1 0 1 0 1 MODE Normal Output Enable Test Bypass Test
NC VDDIR VDDIPD VDD GND
19 1 10 3, 9, 16, 22 4, 5, 8, 13, 17, 21
RefV RefV P G
No Connect Reference for REFCLK: Voltage reference for input reference clock. Reference for Phase Detector: Voltage reference for phase detector inputs and StopB. Power Connection: Power supply for core logic and output buffers. Connected to 3.3V supply. Ground Connection: Connect all ground pins to the common system ground plane.
2
W134M/W134S
W134M/W134S
Refclk
W133 W158 W159 W161 W167 CY2210
PLL
Phase Align D
Busclk
Pclk/M
RMC
RAC
Synclk/N
M
Pclk
N Synclk
4
DLL
Gear Ratio Logic
Figure 1. DDLL System Architecture
DDLL System Architecture and Gear Ratio Logic
Figure 1 shows the Distributed Delay Lock Loop (DDLL) system architecture, including the main system clock source, the Direct Rambus clock generator (DRCG), and the core logic that contains the Rambus Access Cell (RAC), the Rambus Memory Controller (RMC), and the Gear Ratio Logic. (This diagram abstractly represents the differential clocks as a single Busclk wire.) The purpose of the DDLL is to frequency-lock and phase-align the core logic and Rambus clocks (Pclk and Synclk) at the RMC/RAC boundary in order to allow data transfers without incurring additional latency. In the DDLL architecture, a PLL is used to generate the desired Busclk frequency, while a distributed loop forms a DLL to align the phase of Pclk and Synclk at the RMC/RAC boundary. The main clock source drives the system clock (Pclk) to the core logic, and also drives the reference clock (Refclk) to the DRCG. For typical Intel architecture platforms, Refclk will be half the CPU front side bus frequency. A PLL inside the DRCG multiplies Refclk to generate the desired frequency for Busclk, and Busclk is driven through a terminated transmission line (Rambus Channel). At the mid-point of the channel, the RAC senses Busclk using its own DLL for clock alignment, followed by a fixed divide-by-4 that generates Synclk. Pclk is the clock used in the memory controller (RMC) in the core logic, and Synclk is the clock used at the core logic inter-
face of the RAC. The DDLL together with the Gear Ratio Logic enables users to exchange data directly from the Pclk domain to the Synclk domain without incurring additional latency for synchronization. In general, Pclk and Synclk can be of different frequencies, so the Gear Ratio Logic must select the appropriate M and N dividers such that the frequencies of Pclk/M and Synclk/N are equal. In one interesting example, Pclk=133 MHz, Synclk=100 MHz, and M=4 while N=3, giving Pclk/M=Synclk/N=33 MHz. This example of the clock waveforms with the Gear Ratio Logic is shown in Figure 2. The output clocks from the Gear Ratio Logic, Pclk/M, and Synclk/N, are output from the core logic and routed to the DRCG Phase Detector inputs. The routing of Pclk/M and Synclk/N must be matched in the core logic as well as on the board. After comparing the phase of Pclk/M vs. Synclk/N, the DRCG Phase Detector drives a phase aligner that adjusts the phase of the DRCG output clock, Busclk. Since everything else in the distributed loop is fixed delay, adjusting Busclk adjusts the phase of Synclk and thus the phase of Synclk/N. In this manner the distributed loop adjusts the phase of Synclk/N to match that of Pclk/M, nulling the phase error at the input of the DRCG Phase Detector. When the clocks are aligned, data can be exchanged directly from the Pclk domain to the Synclk domain. Table 1 shows the combinations of Pclk and Busclk frequencies of greatest interest, organized by Gear Ratio.
Pclk Synclk Pclk/M = Synclk/N
Figure 2. Gear Ratio Timing Diagram
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W134M/W134S
Table 1. Supported Pclk and Busclk Frequencies, by Gear Ratio Gear Ratio and Busclk Pclk 67 MHz 100 MHz 133 MHz 150 MHz 200 MHz 400 MHz
S0/S1 StopB
2.0
1.5
1.33 300 MHz
1.0 267 MHz 400 MHz
267 MHz
356 MHz 400 MHz
400 MHz
W133 W158 W159 W161 W167 CY2210
W134M/W134S
Refclk
PLL
Phase Align D
Busclk
Pclk/M
RMC
RAC
Synclk/N
M
Pclk
N Synclk
4
DLL
Gear Ratio Logic
Figure 3. DDLL Including Details of DRCG
Figure 3 shows more details of the DDLL system architecture, including the DRCG output enable and bypass modes. Phase Detector Signals The DRCG Phase Detector receives two inputs from the core logic, PclkM (Pclk/M) and SynclkN (Synclk/N). The M and N dividers in the core logic are chosen so that the frequencies of PclkM and SynclkN are identical. The Phase Detector detects the phase difference between the two input clocks, and drives the DRCG Phase Aligner to null the input phase error through the distributed loop. When the loop is locked, the input phase error between PclkM and SynclkN is within the specification tERR,PD given in Table 14 after the lock time given in the State Transition Section. The Phase Detector aligns the rising edge of PclkM to the rising edge of SynclkN. The duty cycle of the phase detector input clocks will be within the specification DCIN,PD given in Table 13. Because the duty cycles of the two phase detector input clocks will not necessarily be identical, the falling edges of PclkM and SynclkN may not be aligned when the rising edges are aligned. The voltage levels of the PclkM and SynclkN signals are determined by the controller. The pin VDDIPD is used as the voltage reference for the phase detector inputs and should be connected to the output voltage supply of the controller. In some applications, the DRCG PLL output clock will be used
directly, by bypassing the Phase Aligner. If PclkM and SynclkN are not used, those inputs must be grounded. Selection Logic Table 2 shows the logic for selecting the PLL prescaler and feedback dividers to determine the multiply ratio for the PLL from the input Refclk. Divider A sets the feedback and divider B sets the prescaler, so the PLL output clock frequency is set by: PLLclk=Refclk*A/B. Table 2. PLL Divider Selection W134M Mult0 0 0 1 1 Mult1 0 1 1 0 A 9 6 8 16 B 2 1 1 3 A 4 6 8 16 W134S B 1 1 1 3
Table 3 shows the logic for enabling the clock outputs, using the StopB input signal. When StopB is HIGH, the DRCG is in its normal mode, and Clk and ClkB are complementary outputs following the Phase Aligner output (PAclk). When StopB is LOW, the DRCG is in the Clk Stop mode, the output clock drivers are disabled (set to Hi-Z), and the Clk and ClkB settle to the DC voltage VX,STOP as given in Table 14. The level of VX,STOP is set by an external resistor network.
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W134M/W134S
Table 3. Clock Stop Mode Selection Mode Normal Clk Stop StopB 1 0 Clk PAclk VX,STOP ClkB PAclkB VX,STOP Table 5. Power-down Mode Selection Mode Normal Power-down PwrDnB 1 0 Clk PAclk GND ClkB PAclkB GND
Table 4 shows the logic for selecting the Bypass and Test modes. The select bits, S0 and S1, control the selection of these modes. The Bypass mode brings out the full-speed PLL output clock, bypassing the Phase Aligner. The Test mode brings the Refclk input all the way to the output, bypassing both the PLL and the Phase Aligner. In the Output Test mode (OE), both the Clk and ClkB outputs are put into a high-impedance state (Hi-Z). This can be used for component testing and for board-level testing. Table 4. Bypass and Test Mode Selection Mode Normal Output Test (OE) Bypass Test S0 0 0 1 1 S1 0 1 0 1 Bypclk (int.) Gnd PLLclk Refclk Clk PAclk Hi-Z PLLclk Refclk ClkB PAclkB Hi-Z PLLclkB RefclkB
Table of Frequencies and Gear Ratios Table 6 shows several supported Pclk and Busclk frequencies, the corresponding A and B dividers required in the DRCG PLL, and the corresponding M and N dividers in the gear ratio logic. The column Ratio gives the Gear Ratio as defined Pclk/Synclk (same as M and N). The column F@PD gives the divided down frequency (in MHz) at the Phase Detector, where F@PD=Pclk/M=Synclk/N. State Transitions The clock source has three fundamental operating states. Figure 4 shows the state diagram with each transition labelled A through H. Note that the clock source output may NOT be glitch-free during state transitions. Upon powering up the device, the device can enter any state, depending on the settings of the control signals, PwrDnB and StopB. In Power-down mode, the clock source is powered down with the control signal, PwrDnB, equal to 0. The control signals S0 and S1 must be stable before power is applied to the device, and can only be changed in Power-down mode (PwrDnB=0). The reference inputs, V DDR and VDDPD, may remain on or may be grounded during the Power-down mode.
Table 5 shows the logic for selecting the Power-down mode, using the PwrDnB input signal. PwrDnB is active LOW (enabled when 0). When PwrDnB is disabled, the DRCG is in its normal mode. When PwrDnB is enabled, the DRCG is put into a powered-off state, and the Clk and ClkB outputs are threestated. Table 6. Examples of Frequencies, Dividers, and Gear Ratios Pclk 67 100 100 133 133 Refclk 33 50 50 67 67 Busclk 267 300 400 267 400 Synclk 67 75 100 67 100
A 8 6 8 4 6
B 1 1 1 1 1
M 2 8 4 4 8
N 2 6 4 2 6
Ratio 1.0 1.33 1.0 2.0 1.33
F@PD 33 12.5 25 33 16.7
VDD Turn-On M
L
VDD Turn-On G
J
Test
N B K
Normal F A D E VDD Turn-On Clk Stop C H
VDD Turn-On Power-Down
Figure 4. Clock Source State Diagram
5
W134M/W134S
The control signals Mult0 and Mult1 can be used in two ways. If they are changed during Power-down mode, then the Powerdown transition timings determine the settling time of the DRCG. However, the Mult0 and Mult1 control signals can also be changed during Normal mode. When the Mult control signals are "hot swapped" in this manner, the Mult transition timings determine the settling time of the DRCG. In Clock Stop mode, the clock source is on, but the output is disabled (StopB asserted). The VDDPD reference input may remain on or may be grounded during the Clk Stop mode. The VDDR reference input must remain on during the Clock Stop mode. In Normal mode, the clock source is on, and the output is enabled. Table 7 lists the control signals for each state. Table 7. Control Signals for Clock Source States State Power-down Clock Stop Normal PwrDnB 0 1 1 StopB X 0 1 Clock Source OFF ON ON Output Buffer Ground Disabled Enabled
Figure 5 shows the timing diagrams for the various transitions between states, and Table 8 specifies the latencies of each state transition. Note that these transition latencies assume the following: * Refclk input has settled and meets specification shown in Table 13. * Mult0, Mult1, S0 and S1 control signals are stable.
Timing Diagrams
Figure 5. State Transition Timing Diagrams Power-Down Exit and Entry
PwrDnB
tPOWERUP tPOWERDN
Clk/ClkB
Output Enable Control
tON tSTOP
StopB
tCLKON tCLKOFF tCLKSETL
Clk/ClkB
Output clock not specified glitches may occur
Clock enabled and glitch free
Clock output settled within 50 ps of the phase before disabled
Figure 6. Multiply Transition Timing
Mult0 and/or Mult1
tMULT Clk/ClkB
6
W134M/W134S
Table 8. State Transition Latency Specifications Transition Latency Transition A C K G H From Power-down Power-down Power-down VDD ON VDD ON To Normal Clk Stop Test Normal Clk Stop Symbol tPOWERUP tPOWERUP tPOWERUP tPOWERUP tPOWERUP Max. 3 ms 3 ms 3 ms 3 ms 3 ms Description Time from PwrDnB to Clk/ClkB output settled (excluding tDISTLOCK). Time from PwrDnB until the internal PLL and clock has turned ON and settled. Time from PwrDnB to Clk/ClkB output settled (excluding tDISTLOCK). Time from VDD is applied and settled until Clk/ClkB output settled (excluding tDISTLOCK). Time from VDD is applied and settled until internal PLL and clock has turned ON and settled. Time from VDD is applied and settled until internal PLL and clock has turned ON and settled. Time from when Mult0 or Mult1 changed until Clk/ClkB output resettled (excluding tDISTLOCK). Time from StopB until Clk/ClkB provides glitch-free clock edges. Time from StopB to Clk/ClkB output settled to within 50 ps of the phase before CLK/CLKB was disabled. Time from StopB to Clk/ClkB output disabled. Time from when S0 or S1 is changed until CLK/CLKB output has resettled (excluding tDISTLOCK). Time from when S0 or S1 is changed until CLK/CLKB output has resettled (excluding tDISTLOCK). Time from PwrDnB to the device in Powerdown.
M
VDD ON
Test
tPOWERUP
3 ms
J
Normal
Normal
tMULT
1 ms
E E
Clk Stop Clk Stop
Normal Normal
tCLKON tCLKSETL
10 ns 20 cycles
F L
Normal Test
Clk Stop Normal
tCLKOFF tCTL
5 ns 3 ms
N
Normal
Test
tCTL
3 ms
B,D
Normal or Clk Stop
Power-down
tPOWERDN
1 ms
Figure 5 shows that the Clk Stop to Normal transition goes through three phases. During tCLKON, the clock output is not specified and can have glitches. For tCLKON< t< tCLKSETL, the clock output is enabled and must be glitch-free. For t>tCLKSETL, the clock output phase must be settled to within
50 ps of the phase before the clock output was disabled. At this time, the clock output must also meet the voltage and timing specifications of Table 14. The outputs are in a high-impedance state during the Clk Stop mode.
7
W134M/W134S
Table 9. Distributed Loop Lock Time Specification Symbol tDISTLOCK Min. Max. 5 Units ms Description Time from when Clk/ClkB output is settled to when the phase error between SynclkN and PclkM falls within the tERR,PD spec in Table 14.
Table 10. Supply and Reference Current Specification Parameter IPOWERDOWN ICLKSTOP INORMAL IREF,PWDN IREF,NORM Description "Supply" current in Power-down state (PwrDnB=0) "Supply" current in Clk Stop state (StopB=0) "Supply" current in Normal state (StopB=1,PwrDnB=1) Current at VDDIR or VDDIPD reference pin in Power-down state (PwrDnB=0) Current at VDDIR or VDDIPD reference pin in Normal or Clk Stop state (PwrDnB=1) Min. -----Max. 250 65 100 50 2 Unit A mA mA A mA
Table 11 represents stress ratings only, and functional operation at the maximums is not guaranteed. Table 11. Absolute Maximum Ratings Parameter VDD, ABS VI, ABS Description Max. voltage on VDD with respect to ground Max. voltage on any pin with respect ground Min. -0.5 -0.5 Max. 4.0 VDD+0.5 Unit V V
Table 12 gives the nominal values of the external components and their maximum acceptable tolerance, assuming ZCH=28. Table 12. External Component Values Parameter RS RP CF CMID Serial Resistor Parallel Resistor Edge Rate Filter Capacitor AC Ground Capacitor Description Min. 39 51 4-15
[1]
Max. 5% 5% 10% 0.1 F
Unit pF 20%
470 pF
Note: 1. Do not populate CF. Leave pads for future use.
8
W134M/W134S
Table 13. Operating Conditions Parameter VDD TA tCYCLE,IN tJ,IN DCIN FMIN PMIN
[3]
Description Supply Voltage Ambient Operating Temperature Refclk Input Cycle Time Input Cycle-to-Cycle Jitter
[2]
Min. 3.135 0 10 40 30 --30 -0.5 25 1 0.7 0.7 0.7 1.235
Max. 3.465 70 40 250 60 33 0.6 0.5
[5]
Unit V C ns ps %tCYCLE kHz % % ns tCYCLE,PD tCYCLE,PD V/ns pF pF pF VDD VDD VDDIR VDDIR VDDIPD VDDIPD V
Input Duty Cycle over 10,000 Cycles Input Frequency of Modulation Modulation Index for Triangular Modulation Modulation Index for Non-Triangular Modulation Phase Detector Input Cycle Time at PclkM & SynclkN Initial Phase error at Phase Detector Inputs Phase Detector Input Duty Cycle over 10,000 Cycles Input Slew Rate (measured at 20%-80% of input voltage) for PclkM, SynclkN, and Refclk Input Capacitance at PclkM, SynclkN, and Refclk[4] Input Capacitance matching at PclkM and SynclkN
[4]
tCYCLE,PD tERR,INIT DCIN,PD tI,SR CIN,PD CIN,PD CIN,CMOS VIL VIH VIL,R VIH,R VIL,PD VIH,PD VDDIR
100 0.5 75 4 7 0.5 10 0.3 0.3 0.3 3.465
Input Capacitance at CMOS pins (excluding PclkM, SynclkN, and Refclk)[4] Input (CMOS) Signal Low Voltage Input (CMOS) Signal High Voltage Refclk input Low Voltage Refclk input High Voltage Input Signal Low Voltage for PD Inputs and StopB Input Signal High Voltage for PD Inputs and StopB Input Supply Reference for Refclk
VDDIPD Input Supply Reference for PD Inputs 1.235 2.625 V Notes: 2. Refclk jitter measured at VDDIR (nom)/2. 3. If input modulation is used: input modulation is allowed but not required. 4. Capacitance measured at Freq=1 MHz, DC bias=0.9V and VAC<100 mV. 5. The amount of allowed spreading for any non-triangular modulation is determined by the induced downstream tracking skew, which cannot exceed the skew generated by the specified 0.6% triangular modulation. Typically, the amount of allowed non-triangular modulation is about 0.5%.
9
W134M/W134S
Table 14. Device Characteristics Parameter tCYCLE tJ Clock Cycle Time Cycle-to-Cycle Jitter at Clk/ClkB [6] Total Jitter over 2, 3, or 4 Clock Cycles 266-MHz Cycle-to-Cycle Jitter tSTEP tERR,PD tERR,SSC VX,STOP VX VCOS VOH VOL rOUT IOZ IOZ,STOP DC tDC,ERR tR,tF tCR,CF
[7] [7] [6]
Description
Min. 2.5 1 -100 -100 1.1 1.3 0.4 1.0
Max. 3.75 60 100 100 160 100 100 2.0 1.8 0.6 2.0 50 50 500 60 50 500 100
Unit ns ps ps ps ps ps ps ps V V V V V A A %tCYCLE ps ps ps
266-MHz Total Jitter over 2, 3, or 4 Clock Cycles Phase Aligner Phase Step Size (at Clk/ClkB)
Phase Detector Phase Error for Distributed Loop Measured at PclkMSynclkN (rising edges) (does not include clock jitter) PLL Output Phase Error when Tracking SSC Output Voltage during Clk Stop (StopB=0) Differential Output Crossing-Point Voltage Output Voltage Swing (p-p single-ended) Output High Voltage Output Low voltage Output Dynamic Resistance (at pins)
[9] [8]
12 40 250 -
Output Current during Hi-Z (S0 = 0, S1 = 1) Output Current during Clk Stop (StopB = 0) Output Duty Cycle over 10,000 Cycles Output Cycle-to-Cycle Duty Cycle Error Output Rise and Fall Times (measured at 20%-80% of output voltage) Difference between Output Rise and Fall Times on the Same Pin of a Single Device (20%-80%)
Notes: 6. Output Jitter spec measured at tCYCLE = 2.5 ns. 7. Output Jitter Spec measured at tCYCLE = 3.75 ns. 8. VCOS = VOH-VOL. 9. rOUT = VO/ IO. This is defined at the output pins.
Ordering Information
Ordering Code W134M/W134S Document #: 38-00822-A Package Name H Package Type 24-pin SSOP (150 mils)
10
W134M/W134S
Layout Example
+3.3V Supply FB
C4 VDDIR G
0.005 F
10 F
C3
G
G
G G G
G G G VDDIPD
1 2 3 4G 5G 6 7 8G 9
10
11 12
24 23 22 G21 20 19 18 G 17 46 15 14 G 13
G G
G G
G
Internal Power Supply Plane
FB = Dale ILB1206 - 300 (300 @ 100 MHz) G = VIA to GND plane layer All Bypass cap = 0.1 Ceramic XR7
11
W134M/W134S
Package Diagram
24-Pin Small Shrink Outline Package (SSOP, 150 mils)
(c) Cypress Semiconductor Corporation, 2000. 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 Semiconductor product. Nor does it convey or imply any license under patent or other rights. Cypress Semiconductor 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 Semiconductor products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress Semiconductor against all charges.

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