Integrated
Circuit
Systems, Inc.
95V857
2.5V Wide Range Frequency Clock Driver (45MHz - 233MHz)
Recommended Application:
• DDR Memory Modules / Zero Delay Board Fan Out
• Provides complete DDR registered DIMM solution
with SSTVF16857, SSTVF16859 or
SSTV32852
Product Description/Features:
• Low skew, low jitter PLL clock driver
• 1 to 10 differential clock distribution (SSTL_2)
• Feedback pins for input to output synchronization
• PD# for power management
• Spread Spectrum-tolerant inputs
• Auto PD when input signal removed
Specifications:
• Meets PC3200 Class A+ specification for DDR-I 400
support
• Covers all DDRI speed grades
Switching Characteristics:
• CYCLE - CYCLE jitter: <50ps
• OUTPUT - OUTPUT skew: <40ps
• Period jitter: ±30ps
Pin Configuration
GND
CLKC0
CLKT0
VDD
CLKT1
CLKC1
GND
GND
CLKC2
CLKT2
VDD
VDD
CLK_INT
CLK_INC
VDD
AVDD
AGND
GND
CLKC3
CLKT3
VDD
CLKT4
CLKC4
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
GND
CLKC5
CLKT5
VDD
CLKT6
CLKC6
GND
GND
CLKC7
CLKT7
VDD
PD#
FB_INT
FB_INC
VDD
FB_OUTC
FB_OUTT
GND
CLKC8
CLKT8
VDD
CLKT9
CLKC9
GND
48-Pin TSSOP/TVSOP
6.10 mm Body, 0.50 mm Pitch = TSSOP
4.40 mm Body, 0.40 mm Pitch = TVSOP
Block Diagram
FB_OUTT
FB_OUTC
CLKT0
CLKC0
Functionality
INPUTS
AVDD PD#
GND
GND
2.5V
(nom)
2.5V
(nom)
2.5V
(nom)
2.5V
(nom)
2.5V
(nom)
H
H
L
L
H
H
X
CLK_INT
L
H
L
H
L
H
<20MHz)
(1)
OUTPUTS
PLL State
CLK_INC CLKT CLKC FB_OUTT FB_OUTC
H
L
H
L
H
L
L
H
Z
Z
L
H
Z
H
L
Z
Z
H
L
Z
L
H
Z
Z
L
H
Z
H
L
Z
Z
H
L
Z
Bypassed/off
Bypassed/off
off
off
on
on
off
95V857
CLKT1
CLKC1
Control
PD#
Logic
CLKT2
CLKC2
CLKT3
CLKC3
CLKT4
CLKC4
FB_INT
FB_INC
CLK_INC
CLK_INT
CLKT5
CLKC5
PLL
CLKT6
CLKC6
CLKT7
CLKC7
CLKT8
CLKC8
CLKT9
CLKC9
0674S—
3/3/2015
95V857
Pin Descriptions
PIN NAME
VDD
GND
AVDD
AGND
CLKT(9:0)
CLKC(9:0)
CLK_INC
CLK_INT
FB_OUTC
TYPE
PWR
PWR
PWR
PWR
OUT
OUT
IN
IN
OUT
Power supply, 2.5V
Ground
Analog power supply, 2.5V
A n a l o g gr o u n d
"Tr ue" Clock of differential pair outputs
"Complementar y" clocks of differential pair outputs
"Complementar y" reference clock input
"True" reference clock input
"Complementar y" Feedback output, dedicated for external feedback. It
switches at the same frequency as the CLK. This output must be wired
to FB_INC
"True" " Feedback output, dedicated for external feedback. It switches
at the same frequency as the CLK. This output must be wired to
FB_INT
"True" Feedback input, provides feedback signal to the internal PLL for
synchronization with CLK_INT to eliminate phase error
"Complementar y" Feedback input, provides signal to the internal PLL
for synchronization with CLK_INC to eliminate phase error
Power Down. LVCMOS input
DESCRIPTION
FB_OUTT
FB_INT
FB_INC
PD#
OUT
IN
IN
IN
This PLL Clock Buffer is designed for a V
DD
of 2.5V, an AV
DD
of 2.5V and differential data input and output levels.
The
95V857
is a zero delay buffer that distributes a differential clock input pair (CLK_INC, CLK_INT) to ten
differential pair of clock outputs (CLKT[0:9], CLKC[0:9]) and one differential pair feedback clock output (FB_OUT,
FB_OUTC). The clock outputs are controlled by the input clocks (CLK_INC, CLK_INT), the feedback clocks (FB_INT,
FB_INC), the 2.5-V LVCMOS input (PD#) and the Analog Power input (AV
DD
). When input (PD#) is low while power is
applied, the receivers are disabled, the PLL is turned off and the differential clock outputs are tri-stated. When AV
DD
is grounded, the PLL is turned off and bypassed for test purposes.
When the input frequency is less than the operating frequency of the PLL, appproximately 20MHz, the device will enter
a low power mode. An input frequency detection circuit on the differential inputs, independent from the input buffers,
will detect the low frequency condition and perform the same low power features as when the (PD#) input is low. When
the input frequency increases to greater than approximately 20 MHz, the PLL will be turned back on, the inputs and
outputs will be enabled and PLL will obtain phase lock between the feedback clock pair (FB_INT, FB_INC) and the input
clock pair (CLK_INC, CLK_INT).
The PLL to the
95V857
clock driver uses the input clocks (CLK_INC, CLK_INT) and the feedback clocks (FB_INT,
FB_INC) provide high-performance, low-skew, low-jitter, output differential clocks (CLKT[0:9], CLKC[0:9]). The
95V857
is also able to track Spread Spectrum Clock (SSC) for reduced EMI.
The
95V857
is characterized for operation from 0°C to 85°C, and will meet JEDEC Standard 82-1 and 82-1A Class
A+ for registered DDR clock drivers.
0674S—
3/3/2015
3
95V857
Absolute Maximum Ratings
Supply Voltage (VDD & AVDD) . . . . . . . . . . .
Logic Inputs . . . . . . . . . . . . . . . . . . . . . . . . .
Ambient Operating Temperature . . . . . . . . . .
Storage Temperature . . . . . . . . . . . . . . . . . . .
-0.5V to 4.6V
GND –0.5 V to V
DD
+ 0.5 V
0°C to +85°C
–65°C to +150°C
Stresses above those listed under
Absolute Maximum Ratings
may cause permanent damage to the device. These
ratings are stress specifications only and functional operation of the device at these or any other conditions above those
listed in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions
for extended periods may affect product reliability.
Electrical Characteristics - Input/Supply/Common Output Parameters
T
A
= 0 - 85°C; Supply Voltage A
VDD
, V
DD
= 2.5V ± 0.2V
PARAMETER
Input High Current
Input Low Current
Operating Supply
Current
Output High Current
Output Low Current
High Impedance
Output Current
Input Clamp Voltage
High-level output
voltage
SYMBOL
I
IH
I
IL
I
DD2.5
I
DDPD
I
OH
I
OL
I
OZ
V
IK
CONDITIONS
V
I
= V
DD
or GND
V
I
= V
DD
or GND
C
L
= 0pf @ 200MHz
C
L
= 0pf
V
DD
= 2.3V, V
OUT
= 1V
V
DD
= 2.3V, V
OUT
= 1.2V
V
DD
=2.7V, Vout=V
DD
or GND
V
DDQ
= 2.3V Iin = -18mA
V
DD
= min to max,
I
OH
= -1 mA
V
DDQ
= 2.3V,
I
OH
= -12 mA
V
DD
= min to max
I
OL
=1 mA
V
DDQ
= 2.3V
I
OH
=12 mA
V
I
= GND or V
DD
V
OUT
= GND or V
DD
V
DDQ
- 0.1
1.7
0.1
0.6
3
3
MIN
5
TYP
MAX
5
170
100
UNITS
µA
µA
mA
µA
mA
mA
±10
-1.2
mA
V
V
V
V
V
pF
pF
148
-18
26
-32
35
V
OH
Low-level output voltage
V
OL
Input Capacitance
1
Output Capacitance
1
1
C
IN
C
OUT
Guaranteed by design at 220MHz, not 100% tested in production.
0674S—
3/3/2015
4
95V857
Recommended Operating Condition
(see note1)
T
A
= 0 - 85°C; Supply Voltage AVDD, VDD = 2.5 V +/- 0.2V (unless otherwise stated)
PARAMETER
Supply Voltage
Low level input voltage
High level input voltage
DC input signal voltage
(note 2)
Differential input signal
voltage (note 3)
Output differential cross-
voltage (note 4)
Input differential cross-
voltage (note 4)
High level output
current
Low level output current
Operating free-air
temperature
SYMBOL
V
DD
, A
VDD
V
IL
V
IH
V
IN
V
ID
V
OX
V
IX
I
OH
I
OL
T
A
0
DC - CLKT, FB_INT
AC - CLKT, FB_INT
CONDITIONS
CLKT, CLKC, FB_INC
PD#
CLKT, CLKC, FB_INC
PD#
MIN
2.3
-0.3
V
DD
/2 + 0.18
1.7
-0.3
0.36
0.7
V
DD
/2 - 0.15
V
DD
/2 - 0.2
V
DD
/2
TYP
2.5
0.4
2.1
V
DD
+ 0.6
V
DD
+ 0.3
V
DD
+ 0.6
V
DD
+ 0.6
V
DD
/2 + 0.15
V
DD
/2 + 0.2
-6.4
5.5
85
MAX
2.7
V
DD
/2 - 0.18
0.7
UNITS
V
V
V
V
V
V
V
V
V
V
mA
mA
°C
Notes:
1. Unused inputs must be held high or low to prevent them from floating.
2. DC input signal voltage specifies the allowable DC execution of differential input.
3. Differential inputs signal voltages specifies the differential voltage [VTR-VCP]
required for switching, where VT is the true input level and VCP is the
complementary input level.
4. Differential cross-point voltage is expected to track variations of V
DD
and is the
voltage at which the differential signal must be crossing.
0674S—
3/3/2015
5
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