Cypress CY2212ZXC-2 Direct rambusâ ¢ clock generator (lite) Datasheet

CY2212
Direct Rambus™ Clock Generator (Lite)
Features
Benefits
• Direct Rambus™ clock support
• One pair of differential output drivers
• High-speed clock support
• 400-MHz maximum, 300-MHz minimum output
frequency
• Input Select option
• PLL multiplier select
• Crystal Oscillator Divider Output
• LCLK = XTAL/2, not driven by phase-locked loop (PLL)
• Output edge-rate control
• Minimize EMI
• 16-pin TSSOP
• Space-saving, low-cost package
Logic Block Diagram
Xtal
PLL
CLK
Oscillator
xM
CLKB
XIN
XOUT
S
/2
LCLK
Xtal Value = 18.75 MHz
Pin Configuration
16-pin TSSOP
TOP VIEW
1
16
S
VSSP
2
15
VDD
XOUT
3
14
VSS
XIN
4
13
CLK
VDDL
5
12
CLKB
LCLK
6
11
VSS
VSSL
7
10
VDD
NC
8
CY2212
VDDP
9
NC
Frequency Select Table
S
M (PLL Multiplier)
CLK,CLKB
LCLK
0
16
300 MHz
9.375 MHz
1
64/3
400 MHz
9.375 MHz
Cypress Semiconductor Corporation
Document #: 38-07466 Rev. *A
•
3901 North First Street
•
San Jose, CA 95134
•
408-943-2600
Revised January 12, 2005
CY2212
Pin Description
Name
Pin
Description
VDDP
1
3.3V Power Supply for PLL
VSSP
2
Ground for PLL
XOUT
3
Reference Crystal Feedback
XIN
4
Reference Crystal Input
VDDL
5
1.8V Power Supply for LCLK
LCLK
6
LVCMOS Output, x1/2 Crystal Frequency
VSSL
7
Ground for LCLK
NC
8
No Connect (Reserved for Test Mode)
NC
9
No Connect (Reserved for Test Mode)
VDD
10
3.3V Power Supply
VSS
11
Ground
CLKB
12
Output Clock (complement), Connect to Rambus Channel
CLK
13
Output Clock, Connect to Rambus Channel
VSS
14
Ground
VDD
15
3.3V Power Supply
S
16
PLL Multiplier Select Input, Pull-up Resistor Internal
Absolute Maximum Conditions
Parameter
VDD,ABS
Description
Min.
Max.
Unit
Max. voltage on VDD, VDDP, or VDDL with respect to ground
–0.5
4.0
V
VI, ABS
Max. voltage on any pin with respect to ground
–0.5
VDD + 0.5
V
VIL, ABS
Max. voltage on LCLK with respect to ground
–0.5
VDDL + 0.5
V
Crystal Requirements
These are the requirements for the recommended crystal to be
used with the CY2212 DRCG Lite clock source. The crystal
load capacitance is internally set to 11 pF.
Parameter
Description
XF
Frequency
XFTOL
Frequency Tolerance[1]
XEQRES
Equivalent Resistance
XTEMP
Temperature Drift[3]
Min.
Max.
Unit
14.0625
18.75
MHz
–15
15
ppm
[2]
100
Ω
10
ppm
XDRIVE
Drive Level
0.01
1500
µW
XMI
Motional Inductance
20.7
25.3
mH
XIR
Insulation Resistance
500
MΩ
XSAR
Spurious Attenuation Ratio[4]
3
dB
XOS
Overtone Spurious
8
dB
Notes:
1. At 25°C ± 3°C.
2. CL = 10 pF.
3. –10°C to 75°C.
4. At XF ± 500 kHz.
Document #: 38-07466 Rev. *A
Page 2 of 10
CY2212
DC Electrical Specifications
Parameter
Description
Min.
Max.
Unit
VDD
Supply voltage
3.04
3.56
V
VDDL
LCLK supply voltage
1.7
2.1
V
TA
Ambient operating temperature
0
70
°C
VIL
Input signal low voltage at pin S
–
0.35
VDD
VIH
Input signal high voltage at pin S
0.65
–
VDD
RPUP
Internal pull-up resistance
10
100
kΩ
AC Electrical Specifications
Parameter
Description
fXTAL,IN
Input frequency at crystal input[5]
CIN,CMOS
Input capacitance at S pin[6]
CXTAL
Crystal load capacitance
Min.
Typ.
Max.
Unit
14.0625
–
18.75
MHz
–
–
10
pF
–
11
–
pF
DC Device Specifications
Parameter
Description
Min.
Max.
Unit
VCM
Differential output common-mode voltage
1.35
1.75
V
VX
Differential output crossing-point voltage
1.25
1.85
V
VCOS
Output voltage swing (p-p single-ended)[7]
0.4
0.7
V
VCOH
Output high voltage
–
2.1
V
VCOL
Output low voltage
1.0
–
V
rOUT
Output dynamic resistance (at pins)[8]
12
50
Ω
VLOH
LCLK Output high voltage at IOH = –10 mA
VDDL – 0.45V
VDDL
V
VLOL
LCLK Output low voltage at IOL = 10 mA
0
0.45
V
State Transition Characteristics
Specifies the maximum settling time of the CLK, CLKB, and
LCLK outputs from device power-up. For VDD, VDDP, and VDDL
any sequences are allowed to power-up and power-down the
CY2212 DRCG-Lite.
From
To
Transition Latency
VDD/VDDL/VDDP On CLK/CLKB/LCLK Normal
3 ms
Description
Time from VDD/VDDL/VDDP is applied and settled to
CLK/CLKB/LCLK outputs settled
AC Device Specifications
Parameter
Description
tCYCLE
Clock cycle time
tJ
Jitter over 1–6 clock cycles at 400 MHz[9]
Jitter over 1–6 clock cycles at 300
tJL
MHz[9]
Long-term jitter at 400 MHz
Long-term jitter at 300 MHz
Min.
Max.
Unit
2.5
3.33
ns
–
100
ps
–
140
ps
–
300
ps
–
400
ps
45%
55%
tCYCLE
Cycle-cycle duty cycle error at 400 MHz
–
50
ps
Cycle-cycle duty cycle error at 300 MHz
–
70
ps
DC
Long-term average output duty cycle
tDC,ERR
Notes:
5. Nominal condition with 18.75-MHz crystal.
6. Capacitance measured at Freq = 1 MHz, DC Bias = 0.9 V, and VAC < 100 mV.
7. VCOS = VOH – VOL.
8. rOUT = ∆ VO/ ∆ IO. This is defined at the output pins, not at the measurement point of Figure 3.
9. Output short-term jitter specification is peak-peak and defined in Figure 10.
Document #: 38-07466 Rev. *A
Page 3 of 10
CY2212
AC Device Specifications (continued)
Parameter
Description
tCR, tCF
Output rise and fall times (measured at 20%–80% of output voltage)
tCR, CF
Difference between output rise and fall times on the same pin of a single
device (20%–80%)
BWLOOP
PLL loop bandwidth
tCYCLE,L
LCLK clock cycle time
tLR, tLF
LCLK output rise and fall time
[10]
tJC,L
LCLK cycle jitter
tJ10,L
LCLK 10-cycle jitter[10,11]
DCL
LCLK output duty cycle
Functional Specifications
Min.
Max.
Unit
250
500
ps
–
100
ps
50 kHz
(–3 dB)
8 MHz
(–20 dB)
106.6
142.2
ns
–
1
ns
–0.8
0.8
ns
–1.1 * tJC,L 1.1 * tJC,L
40%
60%
ns
tCYCLE,L
RSL Clock Output Driver
This section gives the detailed functional specifications of the
device physical layer. These specifications refer to the logical
and physical interfaces.
Crystal Input
The CY2212 receives its reference from an external crystal.
Pin XIN is the reference crystal input, and pin XOUT is the
reference crystal feedback. The parameters for the crystal are
given on page 3 of this data sheet.
Figure 2 shows the clock driver equivalent circuit.
Measurement Point
RT = ZCH
Differential
Driver
RS
RP
ZCH
RP
RSS
ZCH
RT = ZCH
Measurement Point
Select Input
There is only one select input, pin S. This pin selects the
frequency multiplier in the PLL, and is a standard LVCMOS
input. The S pin has an internal pull-up resistor. The multiplier
selection is given on page 1 of this data sheet.
LCLK Output Driver
In addition to the Rambus clock driver outputs, there is another
clock output driver. The LCLK driver is a standard LVCMOS
output driver. Figure 1 below shows the LCLK output driver
load circuit.
LCLK
120Ω
10 pF
120Ω
Figure 1. LCLK Test Load Circuit
Figure 2. Equivalent Circuit
The differential driver has a low output impedance in the range
of about 20 ohms. The driver also produces a specified voltage
swing on the channel. The nominal value of the channel
impedance, ZCH, is 28 ohms. Series resistor RS and parallel
resistor RP are used to set the voltage swing on the channel.
The driver output characteristics are defined together with the
external components, and the output clock is specified at the
measurement point indicated in Figure 2. The complete set of
external components for the output driver, including edge-rate
filter capacitors required for system operation, are shown in
Figure 3. The values for the external components are given in
Table 1.
The output clocks drive transmission lines, potentially long
lines. Since circuit board traces will act as lossy, imperfectly
terminated transmission lines with some discontinuities, there
will be reflections generated which will travel back to the
DRCG-Lite output driver. If the output impedance does not
match ZCH, secondary reflections will be generated that will
add to position-dependent timing uncertainty. Therefore, the
CY2212 not only provides proper output voltage swings, but
also provides a well-matched output impedance. The driver
impedance, ROUT, is in series with RS, and the combination is
in parallel with RP.
The clock driver is specified as a black-box at the packaged
pins. The output characteristics are measured after the series
resistance, RS. The outputs are terminated differentially, with
no applied termination voltage.
Notes:
10. LCLK cycle jitter and 10-cycle jitter are defined as the difference between the measured period and the nominal period as defined on page 8.
11. LCLK 10-cycle jitter specification is based on the measured value of LCLK cycle jitter as defined on page 8.
Document #: 38-07466 Rev. *A
Page 4 of 10
CY2212
Figure 3 below shows the clock driver implemented as a
push-pull driver. When stimulating the output driver, the transmission lines shown in Figure 3 can be replaced by a direct
connection to the termination resistors, RT. The values for the
external components are given in Table 1.
This calculation results in a effective output impedance of
about 27 ohms for the values listed in Table 1. Since the total
impedance is dominated by the external resistors, a large
possible range of ROUT is allowed. When the output is transitioning, the impedance of the CMOS devices increases
dramatically. The purpose of RP is to limit the maximum output
impedance during output transitions.
As mentioned previously, the clock driver’s output impedance
matches the channel impedance. To accomplish this, each of
the output driver devices are sized to have an ROUT of about
20 ohms when fully turned on. ROUT is the dynamic output
resistance, and is defined in the DC Device Characteristics
Table on page 3 of this data sheet. Since ROUT is in series with
RS, and that combination is in parallel with RP, the effective
output impedance is given by:
In order to control signal attenuation and EMI, clock signal
rise/fall times must be tightly controlled. Therefore, external
filter capacitors CF are used to control the output slew rate. In
addition, the capacitor CMID is used to provide AC ground at
the mid-point of the RP resistors.
Table 1 gives the nominal values of the external components
and their maximum acceptable tolerance, assuming
ZCH = 28 ohms.
RP(RS + ROUT)/(RP + RS + ROUT).
CF
RS
DRCG Lite
Measurement Point
RT =ZCH
RP
CMID
ZCH
RP
RS
CF
CMID
RT =ZCH
ZCH
Measurement Point
Figure 3. Output Driver
Table 1. Output External Component Values
Parameter
Value
Tolerance
Unit
RS
Series Resistor
68
±5%
ohm
RP
Parallel Resistor
39
±5%
ohm
CF
Edge-rate Filter Capacitor
15
±10%
pF
0.01
±20%
µF
CMID
Description
AC Ground Capacitor
Measurement Point
RX
ZCH
CF
RS
DRCG Lite
RT = ZCH
RP CMID
CMID
RX
ZCH
RP
RT = ZCH
RX
RS
CF
RT = ZCH
ZCH
CMID
RX
Measurement Point
ZCH
RT = ZCH
Figure 4. Output Driving Two Channels
Document #: 38-07466 Rev. *A
Page 5 of 10
CY2212
Dual-Channel Output Driver
Figure 4 shows the clock driver driving two high-impedance
channels. The purpose of the series resistors RX is to
decouple the two channels, and prevent noise from one
channel from coupling onto the second channel. With ZCH =
40 ohms and the series resistor set to RX = 16 ohms, the
channel becomes an effective 56-ohm channel. The two
channels in parallel can be treated as a single 28-ohm
channel, and all of the external component values listed in
Table 1 can be used.
Signal Waveforms
A physical signal that appears at the pins of the device is
deemed valid or invalid depending on its voltage and timing
relations with other signals. This section defines the voltage
and timing waveforms for the input and output pins of the
CY2212. The Device Characteristics tables list the specifications for the device parameters that are defined here.
and 80% points of the voltage swing, with the swing defined
as VH – VL. For example, the output voltage swing
VCOS = VOH – VOL.
The device parameters defined according to Figure 5 are as
follows.
Table 2. Definition of Device Parameters
Parameter
VOH, VOL
Definition
Clock output high and low voltages
VCOS
Clock output swing VCOS = VOH – VOL
VCM
Common-mode voltage VCM = (VOH – VOL)/2
VIH, VIL
Vdd LVCMOS input high and low voltages
tCR, tCF
Clock output rise and fall times
tCR, CF
Clock output rise/fall time delta tCR,CF =
tCR – tCF
Input and Output voltage waveforms are defined as shown in
Figure 5. Both rise and fall times are defined between the 20%
VOH
80%
V(t)
20%
tCF
VOL
tCR
Figure 5. Voltage Waveforms
CLK
Vx+
Vx,nom
Vx–
CLKB
Figure 6. Crossing-point Voltage
Figure 6 shows the definition of output crossing point. The
nominal crossing point between the complementary outputs is
defined to be at the 50% point of the DC voltage levels. There
are two crossing points defined, Vx+ at the rising edge of CLK
and Vx– at the falling edge of CLK. For some clock waveforms,
both Vx+ and Vx– might be below Vx, nom (for example, if tCR
is larger than tCF). Vx is defined as the differential output
crossing point voltage.
Figure 7 shows the definition of long-term duty cycle, which is
simply the waveform high-time divided by the cycle time
(defined at the crossing point). Long-term duty cycle is the
average over many (>10,000) cycles. Short-term duty cycle is
Document #: 38-07466 Rev. *A
defined in the next section. DC is defined as the output clock
long-term duty cycle.
Jitter
This section defines the specifications that relate to timing
uncertainty (or jitter) of the input and output waveforms.
Figure 8 shows the definition of long-term jitter with respect to
the falling edge of the CLK signal. Long-term jitter is the
difference between the minimum and maximum cycle times.
Equal requirements apply for rising edges of the CLK signal.
tJL is defined as the output long-term jitter.
Page 6 of 10
CY2212
CLK
CLKB
tPW+
tCYCLE
DC = tPW + /tCYCLE
Figure 7. Duty Cycle
CLK
CLKB
tCYCLE
tJL = tCYCLE,max – tCYCLE,min over 10000 cycles
Figure 8. Long-term Jitter
CLK
CLKB
tCYCLE,i
tCYCLE,i+1
tJ = tCYLCE,i – tCYCLE,i + 1 over 10000 consecutive cycles
Figure 9. Cycle-to-cycle Jitter
Figure 9 shows the definition of cycle-to-cycle jitter with
respect to the falling edge of the CLK signal. Cycle-to-cycle
jitter is the difference between cycle times of adjacent cycles.
Equal requirements apply for rising edges of the CLK signal.
tJ is defined as the clock output cycle-to-cycle jitter.
Figure 10 shows the definition of four-cycle short-term jitter.
Short-term jitter is defined with respect to the falling edge of
the CLK. Four-cycle short-term jitter is the difference between
the cumulative cycle times of adjacent four cycles. Equal
requirements apply for rising edges of the CLK signal. Equal
requirements also apply for two-cycle short-term jitter and
three-cycle short-term jitter, and for five-cycle short-term jitter
and six-cycle short-term jitter. tJ is defined as the clock output
short-term jitter over 2, 3, 4, 5, or 6 cycles.
The purpose of this definition of short-term jitter is to define
errors in the measured time (for example, t4CYCLE,i) vs. the
expected time. The purpose for measuring the adjacent time
Document #: 38-07466 Rev. *A
t4CYCLE, i+1 is only to help determine the expected time for
t4CYCLE, i. Alternate methods of determining tJ are possible,
including comparing the measured time to an expected time
based on a local cycle time, tCYCLE,LOCAL. This local cycle time
could be determined by taking the rolling average of a group
of cycles (5–10 cycles) preceding the measured cycles.
However, it is important to differentiate this rolling average
from the average cycle time, tCYCLE,AVG, which is the average
cycle time over the 10,000 cycles. Using a long-term average
instead of a rolling average would define tJ as a long-term jitter
instead of a short-term jitter, and would normally giver overly
pessimistic results.
Figure 11 shows the definition of cycle-to-cycle duty cycle
error. Cycle-to-cycle duty cycle error is defined as the
difference between high-times of adjacent cycles. Equal
requirements apply to the low-times. tDC,ERR is defined as the
clock output cycle-to-cycle duty cycle error.
Page 7 of 10
CY2212
CLK
CLKB
t4CYCLE,i+1
t4CYCLE,i
tJ = t4CYCLE,i – t4CYCLE,i+1 over 10000 consecutive cycles
Figure 10. Short-term Jitter
Cycle i
CLK
Cycle i+1
CLKB
tPW+,i+1
tPW+,i
tCYCLE,i+1
tCYCLE,i+1
tDC,ERR = tPW+,i – tPW+,i+1
Figure 11. Cycle-to-cycle Duty Cycle Error
LCLK
T
10*T
Figure 12. LCLK Jitter
Figure 12 shows the definition of LCLK cycle jitter and LCLK
10-cycle jitter. These parameters apply to the LCLK output,
and not to the Rambus channel clock outputs.
LCLK cycle jitter is the variation in the clock period, T, over a
continuous set of clock cycles. The difference between the
maximum period and the nominal period in the set of clock
cycles measured would be compared to the max spec listed in
the AC Device Characteristics Table on page 3. LCLK cycle
jitter is measured between rising edges at 50% of the output
voltage, and is measured continuously over 30,000 cycles.
LCLK 10-cycle jitter is the variation in the time of 10 clock
cycles, 10*T, where T is the clock period. The difference
between the maximum 10-cycle period and the nominal
10-cycle period in the set of clock cycles measured would be
compared to the max spec listed in the AC Device Characteristics Table on page 5. Note that the specification for LCLK
10-cycle jitter is defined based on the measured value of LCLK
cycle jitter. LCLK 10-cycle jitter is measured between the first
rising edge and the tenth rising edge at 50% of the output
voltage, and is measured over 30,000 continuous cycles. tJC,L
Document #: 38-07466 Rev. *A
is defined as the LCLK output cycle jitter, and tJ10,L is defined
as the LCLK output jitter over 10 cycles.
Measurement
The short-term jitter specification (over one to six cycles) for
the clock source is given as tJ, as previously shown. Jitter
should be measured using a jitter measurement system that
has the flexibility of measuring cycle-to-cycle jitter as a
function of cycle count. It is important that the short-term jitter
be measured over consecutive cycles in order to prevent
long-term drift from causing overly pessimistic results. When
measured over 10,000 consecutive cycles, the short-term jitter
measurements generate large amounts of data which can be
viewed in a histogram. Figure 13 shows an example histogram
of data from a 4-cycle short-term jitter measurement, with
results that are within spec lines for tJ. Note that the jitter is
specified as peak-to-peak, so the center of the histogram need
not be exactly zero.
Further details of jitter measurement methodologies are given
in the Rambus DRCG-Lite Specification Appendix A published
by Rambus, Inc.
Page 8 of 10
CY2212
4 Cycle Jitter
Jitter Spec
Figure 13. Example Jitter Measurement Histogram
Ordering Information
Ordering Code
CY2212ZC-2
CY2212ZC-2T
Package Type
Operating Range
16-lead TSSOP
Commercial
16-lead TSSOP–Tape and Reel
Commercial
16-lead TSSOP
Commercial
16-lead TSSOP–Tape and Reel
Commercial
Lead-Free
CY2212ZXC-2
CY2212ZXC-2T
Package Drawing and Dimensions
16-lead TSSOP 4.40 MM Body Z16.173
PIN 1 ID
DIMENSIONS IN MM[INCHES] MIN.
MAX.
1
REFERENCE JEDEC MO-153
6.25[0.246]
6.50[0.256]
PACKAGE WEIGHT 0.05 gms
PART #
4.30[0.169]
4.50[0.177]
Z16.173
STANDARD PKG.
ZZ16.173 LEAD FREE PKG.
16
0.65[0.025]
BSC.
0.19[0.007]
0.30[0.012]
1.10[0.043] MAX.
0.25[0.010]
BSC
GAUGE
PLANE
0°-8°
0.076[0.003]
0.85[0.033]
0.95[0.037]
4.90[0.193]
5.10[0.200]
0.05[0.002]
0.15[0.006]
SEATING
PLANE
0.50[0.020]
0.70[0.027]
0.09[[0.003]
0.20[0.008]
51-85091-*A
Rambus, RDRAM, and the Rambus Logo are registered trademarks of Rambus Inc. Direct Rambus, RIMM, SORIMM, and Direct
RDRAM are trademarks of Rambus, Inc. All products and company names mentioned in this document may be the trademarks
of their respective holders.
Document #: 38-07466 Rev. *A
Page 9 of 10
© Cypress Semiconductor Corporation, 2005. 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 product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be
used for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress 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
products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
CY2212
Document History Page
Document Title: CY2212 Direct Rambus™ Clock Generator (Lite)
Document Number: 38-07466
REV.
ECN NO.
Issue
Date
Orig. of
Change
Description of Change
**
117801
12/10/02
CKN
New Data Sheet
*A
308300
See ECN
RGL
Corrected Ordering Info from -1 to -2
Added Lead Free Devices (-2)
Added CXTAL specs in the AC Electrical specifications table
Document #: 38-07466 Rev. *A
Page 10 of 10
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