SY89231U
3.2GHz Precision, LVDS ÷3, ÷5 Clock Divider
General Description
The SY89231U is a precision, low jitter 3.2GHz
÷3,
÷5
clock divider with a LVDS output. The differential
input includes Micrel’s unique, 3-pin internal
termination architecture that allows the input to
interface to any differential signal (AC- or DC-
coupled) as small as 100mV (200mV
PP
) without any
level shifting or termination resistor networks in the
signal path. The outputs are 325mV, 100K-
compatible LVDS with fast rise/fall times guaranteed
to be less than 200ps.
The SY89231U operates from a 2.5V ±5% supply
and is guaranteed over the full industrial
temperature range of –40°C to +85°C. The
SY89231U is part of Micrel’s high-speed, Precision
®
Edge product line.
All support documentation can be found on Micrel’s
web site at:
www.micrel.com.
Precision Edge
®
Features
•
Accepts a high-speed input and provides a precision
÷3
and
÷5
sub-rate, LVDS output
•
Guaranteed AC performance over temperature and
supply voltage:
– DC-to >3.2GHz throughput
– <810ps Propagation Delay (In-to-Q)
– <200ps Rise/Fall times
•
Ultra-low jitter design:
– <1ps
RMS
random jitter
– <1ps
RMS
cycle-to-cycle jitter
– <10ps
PP
total jitter (clock)
– <0.7ps
RMS
MUX crosstalk induced jitter
•
Unique patented internal termination and VT pin
accepts DC- and AC-coupled inputs (CML, PECL,
LVDS)
•
Wide input voltage range V
CC
to GND
•
325mV LVDS output
•
45% to 55% Duty Cycle (÷ 3)
•
47% to 53% Duty Cycle (÷ 5)
•
2.5V ±5% supply voltage
•
-40°C to +85°C industrial temperature range
•
Available in 16-pin (3mm x 3mm) QFN package
Block Diagram
Applications
•
Fail-safe clock protection
Markets
•
•
•
•
LAN/WAN
Enterprise servers
ATE
Test and measurement
United States Patent No. RE44,134
Precision Edge is a registered trademark of Micrel, Inc.
.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
November 2007
M9999-110507-A
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SY89231U
Ordering Information
(1)
Part Number
SY89231UMG
SY89231UMGTR
Notes:
1. Contact factory for die availability. Dice are guaranteed at T
A
= 25°C, DC Electricals Only.
2. Tape and Reel.
(2)
Package
Type
QFN-16
QFN-16
Operating
Range
Industrial
Industrial
Package Marking
231U with
Pb-Free bar-line Indicator
231U with
Pb-Free bar-line Indicator
Lead
Finish
NiPdAu
Pb-Free
NiPdAu
Pb-Free
Pin Configuration
16-Pin QFN
November 2007
2
M9999-110507-A
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SY89231U
Pin Description
Pin Number
Pin Name
Pin Function
Differential Input: This input pair is the differential signal input to the device,
which accepts AC- or DC-coupled signal as small as 100mV. The input internally
terminates to a VT pin through 50Ω.
Note that this input pair will default to an
indeterminate state if left open. See “Input Interface Applications” subsection for
more details.
Input Termination Center-Tap: Each side of the differential input pair terminates
to the VT pin. The VT pin provides a center-tap for the input (IN, /IN) to a
termination network for maximum interface flexibility. See “Input Interface
Applications” subsection for more details.
Reference Voltage: This output biases to V
CC
–1.2V. It is used for AC-coupling
inputs IN and /IN. Connect VREF-AC directly to the VT pin. Bypass with 0.01µF
low ESR capacitor to VCC. Due to limited drive capability, the VREF-AC pin is
only intended to drive its respective VT pin. Maximum sink/source current is
±0.5mA. For more details, see “Input Interface Applications” subsection.
Single-ended Input: This TTL/CMOS-compatible input disables and enables the
output. It is internally connected to a 25kΩ pull-up resistor and will default to a
logic HIGH state if left open. When disabled, Q goes LOW and /Q goes HIGH.
EN being synchronous, outputs will be enabled/disabled after a rising and a
falling edge of the input clock. V
TH
= V
CC
/2.
Single-ended Input: This TTL/CMOS-compatible input, when pulled LOW,
asynchronously sets Q output LOW and /Q output HIGH. Note that this input is
internally connected to a 25kΩ pull-up resistor and will default to logic HIGH
state if left open. V
TH
= V
CC
/2.
No Connect
Positive Power Supply: Bypass with 0.1µF in parallel with 0.01µF low ESR
capacitors as close to the V
CC
pins as possible.
Differential Output: The output swing is typically 325mV. The output must be
terminated with 100Ω
across the pair (Q, /Q). See the “Truth Table” below for the
logic function.
Ground: Ground and exposed pad must be connected to a ground plane that is
the same potential as the ground pins.
Single-ended Input: This TTL/CMOS-compatible input selects divide-by-3 when
pulled LOW and divide-by-5 when pulled HIGH. Note that this input is internally
connected to a 25kΩ pull-up resistor and will default to logic HIGH state if left
open. V
TH
= V
CC
/2.
1, 4
IN, /IN
2
VT
3
VREF-AC
5
EN
6
7
8, 13
12, 9
10, 11, 14,15
/MR
NC
VCC
Q, /Q
GND,
Exposed Pad
DIV_SEL
16
Truth Table
Inputs
DIV_SEL
X
0
1
X
EN
X
1
1
0
/MR
0
1
1
1
Outputs
Q
0
/Q
1
÷
3
÷
5
0
÷
3
÷
5
1
November 2007
3
M9999-110507-A
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SY89231U
Absolute Maximum Ratings
(1)
Supply Voltage (V
CC
) .......................... –0.5V to +4.0V
Input Voltage (V
IN
) ..................................–0.5V to V
CC
LVPECL Output Current (I
OUT
)...……………....±10mA
Current (V
T
)
Source or sink current on V
T
.......………±100mA
Input Current
Source or sink current on (IN, /IN) ........... ±50mA
Current (V
REF-AC
)
(4)
Source/Sink Current on V
REF-AC
............ ±0.5mA
Maximum Operating Junction Temperature…..125°C
Lead Temperature (soldering, 20 sec.) .......... +260°C
Storage Temperature (T
s
) ..................–65°C to 150°C
Operating Ratings
(2)
Supply Voltage (V
CC
).................. +2.375V to +2.625V
Ambient Temperature (T
A
) ................ –40°C to +85°C
(3)
Package Thermal Resistance
QFN (θ
JA
)
Still-Air ..................................................... 75°C/W
QFN (ψ
JB
)
Junction-to-Board………………………….33C/W
DC Electrical Characteristics
(5)
T
A
= –40°C to +85°C, unless otherwise stated.
Symbol
V
CC
I
CC
R
IN
R
DIFF_IN
V
IH
V
IL
V
IN
V
DIFF_IN
V
REF-AC
V
T_IN
Notes:
1. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is
not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.
3. Package thermal resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB.
θ
JA
and
ψ
JB
values are determined for a 4-layer board in still air unless otherwise stated.
4. Due to limited drive capability use for input of the same package only.
5. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established.
6. V
IN
(max) is specified when V
T
is floating.
Parameter
Power Supply
Power Supply Current
Input Resistance
(IN-to-V
T
)
Differential Input Resistance
(IN-to-/IN)
Input High Voltage
(IN, /IN)
Input Low Voltage
(IN, /IN)
Input Voltage Swing
(IN, /IN)
Differential Input Voltage Swing
|IN-/IN|
Output Reference Voltage
Voltage from Input to V
T
Condition
No load, max V
CC
Min
2.375
45
90
1.2
0
Typ
2.5
71
50
100
Max
2.625
95
55
110
V
CC
V
IH
–0.1
V
CC
Units
V
mA
Ω
Ω
V
V
V
V
See Figure 2a. Note 6.
See Figure 2b.
0.1
0.2
V
CC
–1.3
V
CC
–1.2
V
CC
–1.1
1.8
V
V
November 2007
4
M9999-110507-A
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SY89231U
LVDS Outputs DC Electrical Characteristics
(7)
V
CC
= +2.5V ±5%, R
L
= 100Ω across the outputs; T
A
= –40°C to +85°C, unless otherwise stated.
Symbol
V
OUT
V
DIFF_OUT
V
OCM
∆V
OCM
Parameter
Output Voltage Swing (Q, /Q)
Differential Output Voltage Swing |Q – /Q|
Output Common Mode Voltage (Q, /Q)
Change in Common Mode Voltage (Q, /Q)
Condition
See Figure 2a
See Figure 2b
See Figure 5a
See Figure 5b
Min
250
500
1.125
–50
Typ
325
650
1.20
1.275
+50
Max
Units
mV
mV
V
mV
LVTTL/CMOS DC Electrical Characteristics
(7)
V
CC
= 2.5V ±5%; T
A
= –40°C to + 85°C, unless otherwise stated.
Symbol
V
IH
V
IL
I
IH
I
IL
Note:
7. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established.
Parameter
Input HIGH Voltage
Input LOW Voltage
Input HIGH Current
Input LOW Current
Condition
Min
2.0
Typ
Max
0.8
Units
V
V
µA
µA
-125
-300
30
November 2007
5
M9999-110507-A
hbwhelp@micrel.com
or (408) 955-1690
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