Cypress CY28401OXC 100-mhz differential buffer for pci express and sata Datasheet

CY28401
100-MHz Differential Buffer for PCI Express and SATA
Features
Functional Description
• CK409 or CK410 companion buffer
The CY28401 is a differential buffer and serves as a
companion device to the CK409 or CK410 clock generator.
The device is capable of distributing the Serial Reference
Clock (SRC) in PCI Express and SATA implementations.
• Eight differential 0.7V clock pairs
• Individual OE controls
• Low CTC jitter (< 50 ps)
• Programmable bandwidth
• SRC_STOP# power management control
• SMBus Block/Byte/Word Read and Write support
• 3.3V operation
• PLL Bypass-configurable
• Divide by 2 programmable
• 48-pin SSOP package
Pin Configuration
Block Diagram
DIFT0
OE_[0:7]
SRC_STOP#
PWRDWN#
DIFC0
Output
Control
DIFT1
DIFC1
DIFT2
SDATA
SMBus
Controller
DIFC2
DIFT3
SRC_DIV2#
Output
Buffer
PLL/BYPASS#
DIFC3
DIFT4
DIFC4
SRCT_IN
SRCC_IN
DIFT5
DIFC5
DIV
HIGH_BW#
DIFT6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
CY28401
SCLK
SRC_DIV2#
VDD
VSS
SRCT_IN
SRCC_IN
OE_0
OE_3
DIFT0
DIFCO
VSS
VDD
DIFT1
DIFC1
OE_1
OE_2
DIFT2
DIFC2
VSS
VDD
DIFT3
DIFC3
PLL/BYPASS#
SCLK
SDATA
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
VDD_A
VSS_A
IREF
LOCK
OE_7
OE_4
DIFT7
DIFC7
VSS
VDD
DIFT6
DIFC6
OE_6
OE_5
DIFT5
DIFC5
VSS
VDD
DIFT4
DIFC4
HIGH_BW#
SRC_STOP#
PWRDWN#
VSS
DIFC6
PLL
48 SSOP
DIFT7
DIFC7
LOCK
Cypress Semiconductor Corporation
Document #: 38-07592 Rev. *A
•
3901 North First Street
•
San Jose, CA 95134
•
408-943-2600
Revised July 14, 2005
CY28401
Pin Description
Pin
Name
4,5
SRCT_IN, SRCC_IN
8,9,12,13,16,17,20,21,29,30, DIFT/C(7:0)
33,34,37,38,41,42
Type
I,DIF
Description
0.7V Differential SRC inputs from the clock synthesizer
O,DIF 0.7V Differential Clock Outputs
6,7,14,15,35,36,43,44
OE_(7:0)
I,SE
3.3V LVTTL active LOW input for three-stating differential
outputs
28
HIGH_BW#
I,SE
3.3V LVTTL input for selecting PLL bandwidth
45
LOCK
O,SE
3.3V LVTTL output, transitions high when PL lock is
achieved (latched output)
26
PWRDWN#
I,SE
3.3V LVTTL input for Power-down, active LOW
1
SRC_DIV/2#
I,SE
3.3V LVTTL input for selecting input frequency divided by
two, active LOW
27
SRC_STOP#
I,SE
3.3V LVTTL input for SRC_Stop#, active LOW
I,SE
SMBus Slave Clock Input
23
SCLK
24
SDATA
46
IREF
I/O,OC Open collector SMBus data
I
A precision resistor is attached to this pin to set the differential output current
I
3.3V LVTTL input for selecting fan-out or PLL operation
22
PLL/BYPASS#
48
VDD_A
3.3V
3.3V Power Supply for PLL
47
VSS_A
GND
Ground for PLL
3,10,18,25,32,40
VSS
I
Ground for outputs
2,11,19,31,39
VDD
I
3.3V power supply for outputs
Serial Data Interface
Data Protocol
To enhance the flexibility and function of the clock buffer, 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 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.
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 1.
The block write and block read protocol is outlined in Table 2
while Table 3 outlines the corresponding byte write and byte
read protocol. The slave receiver address is 11011100 (DCh).
Table 1. Command Code Definition
Bit
7
(6:0)
Description
0 = Block read or block write operation
1 = Byte read or byte write operation
Byte offset for byte read or byte write operation. For block read or block write operations, these bits should be
'0000000'
Table 2. Block Read and Block Write Protocol
Block Write Protocol
Bit
1
2:8
9
Description
Start
Slave address – 7 bits
Write = 0
Document #: 38-07592 Rev. *A
Block Read Protocol
Bit
1
2:8
9
Description
Start
Slave address – 7 bits
Write = 0
Page 2 of 14
CY28401
Table 2. Block Read and Block Write Protocol (continued)
Block Write Protocol
Bit
10
11:18
19
20:27
28
29:36
37
38:45
Block Read Protocol
Description
Bit
Acknowledge from slave
Description
10
Command Code – 8 bits
'00000000' stands for block operation
Acknowledge from slave
11:18
Command Code – 8 bits
'00000000' stands for block operation
Acknowledge from slave
19
Acknowledge from slave
Byte Count from master – 8 bits
20
Repeat start
Acknowledge from slave
21:27
Data byte 0 from master – 8 bits
Acknowledge from slave
Data byte 1 from master – 8 bits
Acknowledge from slave
....
Data bytes from master/Acknowledge
....
Data Byte N – 8 bits
....
Acknowledge from slave
....
Stop
Read = 1
29
Acknowledge from slave
30:37
46
Slave address – 7 bits
28
38
Byte count from slave – 8 bits
Acknowledge from host
39:46
47
Data byte 0 from slave – 8 bits
Acknowledge from host
48:55
Data byte 1 from slave – 8 bits
56
Acknowledge from host
....
Data bytes from slave/Acknowledge
....
Data byte N from slave – 8 bits
....
Acknowledge from host
....
Stop
Table 3. Byte Read and Byte Write Protocol
Byte Write Protocol
Bit
1
2:8
9
10
11:18
19
20:27
Byte Read Protocol
Description
Bit
Start
1
Slave address – 7 bits
2:8
Write = 0
Acknowledge from slave
Command Code – 8 bits
'100xxxxx' stands for byte operation, bits[6:0] of the
command code represents the offset of the byte to be
accessed
Acknowledge from slave
Data byte from master – 8 bits
28
Acknowledge from slave
29
Stop
Description
Start
Slave address – 7 bits
9
Write = 0
10
Acknowledge from slave
11:18
19
20
21:27
Command Code – 8 bits
'100xxxxx' stands for byte operation, bits[6:0]
of the command code represents the offset of
the byte to be accessed
Acknowledge from slave
Repeat start
Slave address – 7 bits
28
Read = 1
29
Acknowledge from slave
30:37
Data byte from slave – 8 bits
38
Acknowledge from master
39
Stop
Byte 0: Control Register 0
Bit
@pup
7
0
PWRDWN# drive mode
0 = Driven when stopped, 1 = Three-state
6
0
SRC_STOP# drive mode
0 = Driven when stopped, 1 = Three-state
Document #: 38-07592 Rev. *A
Name
Description
Page 3 of 14
CY28401
Byte 0: Control Register 0 (continued)
Bit
@pup
Name
Description
5
0
Reserved
4
0
Reserved
3
0
Reserved
2
1
HIGH_BW#
0 = High Bandwidth, 1 = Low bandwidth
1
1
PLL/Bypass#
0 = Fanout buffer, 1 = PLL mode
0
1
SRC_DIV/2
0 = Divided by 2 mode, 1 = Normal (output = input)
Byte 1: Control Register 1
Bit
@pup
Name
Description
7
1
DIF_7 Output Enable
0 = Disabled (three-state)
1 = Enabled
6
1
DIF_6 Output Enable
0 = Disabled (three-state)
1 = Enabled
5
1
DIF_5 Output Enable
0 = Disabled (three-state)
1 = Enabled
4
1
DIF_4 Output Enable
0 = Disabled (three-state)
1 = Enabled
3
1
DIF_3 Output Enable
0 = Disabled (three-state)
1 = Enabled
2
1
DIF_2 Output Enable
0 = Disabled (three-state)
1 = Enabled
1
1
DIF_1 Output Enable
0 = Disabled (three-state)
1 = Enabled
0
1
DIF_0 Output Enable
0 = Disabled (three-state)
1 = Enabled
Byte 2: Control Register 2
Bit
@pup
7
0
Allow Control DIF_7 with assertion of SRC_STOP#
0 = Free-running
1 = Stopped with SRC_STOP#
6
0
Allow Control DIF_6 with assertion of SRC_STOP#
0 = Free-running
1 = Stopped with SRC_STOP#
5
0
Allow Control DIF_5 with assertion of SRC_STOP#
0 = Free-running
1 = Stopped with SRC_STOP#
4
0
Allow Control DIF_4 with assertion of SRC_STOP#
0 = Free-running
1 = Stopped with SRC_STOP#
Document #: 38-07592 Rev. *A
Name
Description
Page 4 of 14
CY28401
Byte 2: Control Register 2 (continued)
Bit
@pup
Name
Description
3
0
Allow Control DIF_3 with assertion of SRC_STOP#
0 = Free-running
1 = Stopped with SRC_STOP#
2
0
Allow Control DIF_2 with assertion of SRC_STOP#
0 = Free-running
1 = Stopped with SRC_STOP#
1
0
Allow Control DIF_1 with assertion of SRC_STOP#
0 = Free-running
1 = Stopped with SRC_STOP#
0
0
Allow Control DIF_0 with assertion of SRC_STOP#
0 = Free-running
1 = Stopped with SRC_STOP#
Byte 3: Control Register 3
Bit
@pup
7
0
Name
Reserved
Description
6
0
Reserved
5
0
Reserved
4
0
Reserved
3
0
Reserved
2
0
Reserved
1
0
Reserved
0
0
Reserved
Byte 4: Vendor ID Register
Bit
@Pup
7
0
Name
Revision Code Bit 3
Description
6
0
Revision Code Bit 2
5
0
Revision Code Bit 1
4
0
Revision Code Bit 0
3
1
Vendor ID Bit 3
2
0
Vendor ID Bit 2
1
0
Vendor ID Bit 1
0
0
Vendor ID Bit 0
Byte 5: Control Register 5
Bit
@Pup
7
0
Reserved
6
0
Reserved
5
0
Reserved
4
0
Reserved
3
0
Reserved
2
0
Reserved
1
0
Reserved
0
0
Reserved
Document #: 38-07592 Rev. *A
Name
Description
Page 5 of 14
CY28401
PWRDWN# Clarification[1]
three-stated (depending on the state of the control register
drive mode and OE bits) on the next DIFC HIGH-to-LOW
transition. When the SMBus power-down drive mode bit is
programmed to ‘0’, all clock outputs will be held with the DIFT
pin driven high at 2 x Iref and DIFC three-state. However, if the
control register PWRDWN# drive mode bit is programmed to
‘1’, then both DIFT and the DIFC are three-stated.
The PWRDWN# pin is used to shut off all clocks cleanly and
instruct the device to evoke power savings mode. Additionally,
PWRDWN# should be asserted prior to shutting off the input
clock or power to ensure all clocks shut down in a glitch-free
manner. PWRDWN# is an asynchronous active LOW input.
This signal is synchronized internal to the device prior to
powering down the clock buffer. PWRDWN# is an
asynchronous input for powering up the system. When
PWRDWN# is asserted LOW, all clocks will be held HIGH or
three-stated (depending on the state of the control register
drive mode and OE bits) prior to turning off the VCO. All clocks
will start and stop without any abnormal behavior and must
meet all AC and DC parameters. This means no glitches,
frequency shifting or amplitude abnormalities among others.
PWRDWN# Deassertion
The power-up latency is less than 1 ms. This is the time from
the deassertion of the PWRDWN# pin or the ramping of the
power supply or the time from valid SRC_IN input clocks until
the time that stable clocks are output from the buffer chip (PLL
locked). If the control register PWRDWN# three-state bit is
programmed to ‘1’, all differential outputs must be driven high
in less than 300 µs of PWRDWN# deassertion to a voltage
greater than 200 mV.
PWRDWN# Assertion
When PWRDWN# is sampled LOW by two consecutive rising
edges of DIFC, all DIFT outputs will be held HIGH or
PWRDWN#
DIFT
DIFC
Figure 1. PWRDWN# Assertion Diagram
Tstable
<1mS
PWRDWN#
DIFT
DIFC
Tdrive_Pwrdwn#
<300uS, >200mV
Figure 2. PWRDWN# Deassertion Diagram
Table 4. Buffer Power-up State Machine
State
Description
0
3.3V Buffer power off
1
After 3.3V supply is detected to rise above 1.8V - 2.0V, the buffer enters state 1 and initiates a 0.2-ms–0.3-ms delay
2[5]
3[2,3,4]
Buffer waits for a valid clock on the SRC_IN input and PWRDWN# deassertion
Once the PLL is locked to the SRC_IN input clock, the buffer enters state 3 and enables outputs for normal operation
Notes:
1. Disabling of the SRCT_IN input clock prior to assertion of PWRDWN# is an undefined mode and not recommended. Operation in this mode may result in glitches
excessive frequency shifting.
2. The total power-up latency from power on to all outputs active is less than 1 ms (assuming a valid clock is present on SRC_IN input).
3. Lock output is a latched signal that is reset with the assertion of PWRDWN# or when VDD < 1.8V,
4. Special care must be taken to ensure that no abnormal clock behavior occurs after the assertion PLL LOCK (i.e., overshoot undershoot is allowed).
5. If power is valid and PWRDWN# is deasserted but no input clocks are present on the SRC_IN input, DIF clocks will remain disabled. Only after valid input clocks
are detected, valid power, PWRDWN# deasserted with the PLL locked and stable are the DIF outputs enabled.
Document #: 38-07592 Rev. *A
Page 6 of 14
CY28401
No Input Clock
S2
S1
Wait for Input
Clock &
PWRDWN# Deassertion
Delay
>0.25ms
PWRDWN# Asserted
S3
S0
Normal
Operation
Power Off
Figure 3. Buffer Power-up State Diagram
SRC_STOP# Clarification
The SRC_STOP# signal is an active LOW input used for clean
stopping and starting the DIFT/C outputs (valid clock must be
present on SRCT/C_IN). The SRC_STOP# signal is a
debounced signal in that its state must remain unchanged
during two consecutive rising edges of DIFC to be recognized
as a valid assertion or deassertion. (The assertion and
deassertion of this signal is absolutely asynchronous.)
transition. When the control register SRC_STOP# three-state
bit is programmed to ‘0’, the final state of all stopped DIFT/C
signals is DIFT clock = HIGH and DIFC = LOW. There will be
no change to the output drive current values, DIFT will be
driven HIGH with a current value equal 6 x Iref, and DIFC will
not be driven. When the control register SRC_STOP#
three-state bit is programmed to ‘1’, the final state of all
stopped DIF signals is LOW, both DIFT clock and DIFC clock
outputs will not be driven.
Table 5. SRC_STOP# Functionality[6]
SRC_STOP# Deassertion
SRC_STOP#
DIFT
DIFC
1
Normal
Normal
0
Iref * 6 or Float
Low
SRC_STOP# Assertion
The impact of asserting the SRC_STOP# pin is that all DIF
outputs that are set in the control registers to stoppable via
assertion of SRC_STOP# are stopped after their next
All differential outputs that were stopped will resume normal
operation in a glitch-free manner. The maximum latency from
the deassertion to active outputs is between 2-6 DIFT/C clock
periods (2 clocks are shown) with all DIFT/C outputs resuming
simultaneously. If the control register three-state bit is
programmed to ‘1’ (three-state), then all stopped DIFT outputs
will be driven high within 10 ns of SRC_STOP# deassertion to
a voltage greater than 200 mV.
1mS
SRC_STOP#
PWRDWN#
DIFT(Free Running
DIFC(Free Running
DIFT (Stoppable)
DIFC (Stoppable)
Figure 4. SRC_STOP# = Driven, PWRDWN# = Driven
Note:
6. In the case where OE is asserted LOW, the output will always be three-stated regardless of SRC_STOP# drive mode register bit state.
Document #: 38-07592 Rev. *A
Page 7 of 14
CY28401
1mS
SRC_STOP#
PWRDWN#
DIFT(Free Running
DIFC(Free Running
DIFT (Stoppable)
DIFC (Stoppable)
Figure 5. SRC_STOP# =Driven, PWRDWN# = Three-state
1mS
SRC_STOP#
PWRDWN#
DIFT(Free Running
DIFC(Free Running
DIFT (Stoppable)
DIFC (Stoppable)
Figure 6. SRC_STOP# =Three-state, PWRDWN# = Driven
1mS
SRC_STOP#
PWRDWN#
DIFT(Free Running
DIFC(Free Running
DIFT (Stoppable)
DIFC (Stoppable)
Figure 7. SRC_STOP# =Three-state, PWRDWN# = Three-state
Output Enable Clarification
The OE function may be implemented in two ways, via writing
a ‘0’ to SMBus register bit corresponding to output of interest
or by asserting an OE input pin LOW. In both methods, if
SMBus registered bit has been written LOW or the OE pin is
LOW or both, the output of interest will be three-stated. (The
assertion and deassertion of this signal is absolutely
asynchronous.)
Table 6. OE Functionality
OE (Pin)#
OE (SMBus Bit)
DIFT
DIFC
1
1
1
Normal
Normal
0
Three-state
Low
0
1
Three-state
Low
0
0
Three-state
Low
Document #: 38-07592 Rev. *A
Page 8 of 14
CY28401
OE Assertion (Transition from ‘0’ to ‘1’)
All differential outputs that were three-stated will resume
normal operation in a glitch-free manner. The maximum
latency from the assertion to active outputs is between 2–6 DIF
clock periods. In addition, DIFT clocks will be driven HIGH
within 10 ns of OE assertion to a voltage greater than 200 mV.
OE Deassertion (Transition from ‘1’ to ‘0’)
The impact of deasserting OE is each corresponding output
will transition from normal operation to three-state in a
glitch-free manner. The maximum latency from the
deassertion to three-stated outputs is between 2–6 DIF clock
periods.
LOCK Signal Clarification
The LOCK output signal is intended to provide designers a
signal indicating that PLL lock has been achieved and valid
clock are available. This can be helpful when cascading
multiple buffers that each contribute a 1-ms start-up delay in
addition to the start-up time of the clock source. Upon
receiving a valid clock on the SRC_IN input (PWRDWN#
deasserted), the buffer will begin ramping the internal PLL until
lock is achieved and stable, the clock buffer will assert the
LOCK pin HIGH and enable DIF output clocks. In other words,
if power is valid and PWRDWN# is deasserted but no input
clocks are present on the SRC_IN input, all DIF clocks remain
disabled. Only after valid input clocks are detected, valid
power, PWRDWN# deasserted with the PLL locked and stable
are LOCK to be asserted and the DIF outputs enabled. The
maximum start-up latency from valid clocks on SRC_IN input
to the assertion of LOCK (output clocks are valid) is to be less
than 1 ms. Once LOCK has been asserted high, it will remain
high (regardless of the actual PLL status) until power is
removed or the PWRDWN# pin has been asserted.
SRC_DIV2# Clarification
The SRC_DIV2# input is used to configure the DIF output
mode to be equal to the SRC_IN input frequency or half the
input frequency in a glitch-free manner. The SRC_DIV2#
Document #: 38-07592 Rev. *A
function may be implemented in two ways, via writing a ‘0’ to
SMBus register bit or by asserting the SRC_DIV2# input pin
LOW. In both methods, if the SMBus register bit has been
written LOW or the SRC_DIV2# pin is LOW or both, all DIF
outputs will configured for divide by 2 operation.
SRC_DIV2# Assertion
The impact of asserting the SRC_DIV2# is that all DIF outputs
will transition cleanly in a glitch-free manner from normal
operation (output frequency equal to input) to half the input
frequency within 2–6 DIF clock periods.
SRC_DIV2# Deassertion
The impact of deasserting the SRC_DIV2# is that all DIF
outputs will transition cleanly in a glitch-free manner from
divide by 2 mode to normal (output frequency is equal to the
input frequency) operation within 2–6 DIF clock periods.
PLL/BYPASS# Clarification
The PLL/Bypass# input is used to select between bypass
mode (no PLL) and PLL mode. In bypass mode, the input clock
is passed directly to the output stage resulting in 50-ps additive
jitter (50 ps + input jitter) on DIF outputs. In the case of PLL
mode, the input clock is pass through a PLL to reduce
high-frequency jitter. The BYPASS# mode may be selected in
two ways, via writing a ‘0’ to SMBus register bit or by asserting
the PLL/BYPASS# pin LOW. In both methods, if the SMBus
register bit has been written LOW or PLL/BYPASS# pin is
LOW or both, the device will be configured for BYPASS
operation.
HIGH_BW# Clarification
The HIGH_BW# input is used to set the PLL bandwidth. This
mode is intended to minimize PLL peaking when two or more
buffers are cascaded by staggering device bandwidths. The
PLL low-bandwidth mode may be selected in two ways, via
writing a ‘0’ to SMBus register bit or by asserting the
HIGH_BW# pin is LOW or both; the device will be configured
for low-bandwidth operation.
Page 9 of 14
CY28401
Absolute Maximum Conditions
Parameter
Description
Condition
Min.
Max.
Unit
VDD
Core Supply Voltage
–0.5
4.6
V
VDD_A
Analog Supply Voltage
–0.5
4.6
V
VIN
Input Voltage
Relative to V SS
–0.5
VDD + 0.5
VDC
TS
Temperature, Storage
Non-functional
–65
+150
°C
TA
Temperature, Operating Ambient
Functional
70
°C
TJ
Temperature, Junction
Functional
150
°C
ØJC
Dissipation, Junction to Case
Mil-Spec 883E Method 1012.1
TBD
°C/W
ØJA
Dissipation, Junction to Ambient
JEDEC (JESD 51)
TBD
°C/W
ESDHBM
ESD Protection (Human Body Model)
MIL-STD-883, Method 3015
UL-94
Flammability Rating
At 1/8 in.
MSL
Moisture Sensitivity Level
0
2000
V
V–0
1
Multiple Supplies: The Voltage on any input or I/O pin cannot exceed the power pin during power-up. Power supply sequencing is NOT required.
DC Electrical Specifications
Parameter
Description
Condition
Min.
Max.
Unit
3.135
3.465
V
VDD_A,
VDD
3.3V Operating Voltage
3.3 ± 5%
VILI2C
Input Low Voltage
SDATA, SCLK
–
1.0
V
VIHI2C
Input High Voltage
SDATA, SCLK
2.2
–
V
VIL
3.3V Input Low Voltage
VSS – 0.5
0.8
V
VIH
3.3V Input High Voltage
2.0
VDD + 0.5
V
VOL
3.3V Output Low Voltage
IOL = 1 mA
–
0.4
V
VOH
3.3V Output High Voltage
IOH = –1 mA
2.4
–
V
IIL
Input Low Leakage Current
Except internal pull-up resistors, 0 < VIN < VDD
–5
IIH
Input High Leakage Current
Except internal pull-down resistors, 0 < VIN < VDD
µA
5
µA
–10
10
µA
2
5
pF
IOZ
High-impedance Output Current
CIN
Input Pin Capacitance
COUT
Output Pin Capacitance
3
6
pF
LIN
Pin Inductance
–
7
nH
IDD3.3V
Dynamic Supply Current
At max. load and 100 MHz
–
300
mA
IPD3.3V
Power-down Supply Current
PD asserted, Outputs driven
–
65
mA
IPD3.3V
Power-down Supply Current
PD asserted, Outputs Three-stated
–
5
mA
AC Electrical Specifications
Parameter
Description
DIF at 0.7V
TDC
DIFT and DIFC Duty Cycle
Condition
Measured at crossing point VOX
TSKEW
Any DIFT/C to DIFT/C Clock Skew, SSC Measured at crossing point VOX
TPERIOD
Average Period
Measured at crossing point VOX at 100 MHz
TCCJ
DIFT/C Cycle to Cycle Jitter
Measured at crossing point VOX
TR / TF
DIFT and DIFC Rise and Fall Times
Measured from VOL = 0.175 to VOH = 0.525V
TRFM
Rise/Fall Matching
Determined as a fraction of 2*(TR – TF)/(TR + TF)
∆TR
Rise Time Variation
∆TF
Fall Time Variation
VHIGH
Voltage High
Document #: 38-07592 Rev. *A
Measured SE
Min.
Max.
Unit
45
55
%
–
200
ps
9.9970
10.0533
ns
–
50
ps
175
700
ps
–
20
%
–
125
ps
–
125
ps
660
850
mv
Page 10 of 14
CY28401
AC Electrical Specifications (continued)
Parameter
Description
Condition
Measured SE
Min.
Max.
Unit
–150
–
mv
VLOW
Voltage Low
VOX
Crossing Point Voltage at 0.7V Swing
250
550
mv
∆VOX
Vcross Variation over all edges
–
140
mV
VOVS
Maximum Overshoot Voltage
–
VHIGH + 0.3
V
VUDS
Minimum Undershoot Voltage
–
–0.3
V
VRB
Ring Back Voltage
Measured SE
tPD(PLL)
Input to output skew in PLL mode
Measured at crossing point VOX
tPD(NONPLL) Input to output skew in Non–PLL mode Measured at crossing point VOX
D IF T
D IF C
IR E F
475Ω
T PCB
33Ω
4 9 .9 Ω
N/A
V
–
±250
ps
2.5
6.5
ns
M e a s u re m e n t
P o in t
2pF
T PCB
33Ω
0.2
4 9 .9 Ω
M e a s u re m e n t
P o in t
2pF
T r a c e Im p e d a n c e M e a s u r e d D if f e r e n tia lly
Figure 8. Differential Clock Termination
Switching Waveforms
TRise (CLOCK)
VOH = 0.525V
CL
OC
K#
K
OC
CL
VCROSS
VOL = 0.175V
TFall (CLOCK)
Figure 9. Single-Ended Measurement Points for TRise and TFall
Document #: 38-07592 Rev. *A
Page 11 of 14
CY28401
VOVS
VRB
VRB
VLOW
VUDS
Figure 10. Single-ended Measurement Points for VOVS,VUDS and VRB
TPERIOD
Skew Management Point
High Duty Cycle %
Low Duty Cycle %
0.000V
Figure 11. Differential (Clock-CLock#) Measurement Points (Tperiod, Duty Cycle and Jitter)
Ordering Information
Ordering Code
Package Type
Operating Range
CY28401OC
48-pin SSOP
Commercial, 0°C to 70 °C
CY28401OCT
48-pin SSOP–Tape and Reel
Commercial, 0°C to 70 °C
CY28401OXC
48-pin SSOP
Commercial, 0°C to 70 °C
CY28401OXCT
48-pin SSOP–Tape and Reel
Commercial, 0°C to 70 °C
Lead-Free
Document #: 38-07592 Rev. *A
Page 12 of 14
CY28401
Package Drawing and Dimensions
48-Lead Shrunk Small Outline Package O48
51-85061-*C
All products and company names mentioned in this document may be the trademarks of their respective holders.
Document #: 38-07592 Rev. *A
Page 13 of 14
© 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.
CY28401
Document History Page
Document Title: CY28401 100-MHz Differential Buffer for PCI Express and SATA
Document Number: 38-07592
Rev.
ECN No.
Issue Date
Orig. of
Change
Description of Change
**
130191
11/26/03
IJA/SDR
New Data Sheet
*A
387766
See ECN
RGL
Added Lead-free
Document #: 38-07592 Rev. *A
Page 14 of 14
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