1
PS8639B 10/29/03
Product Description
PI6CV857B PLL clock device is developed for registered DDR DIMM
applications This PLL Clock Buffer is designed for 2.5 V
DDQ
and 2.5V
AV
DD
operation and differential data input and output levels.
The device is a zero delay buffer that distributes a differential clock
input pair (CLK, CLK) to ten differential pairs of clock outputs (Y[0:9],
Y[0:9]) and one differential pair feedback clock outputs
(FBOUT,FBOUT) . The clock outputs are controlled by the input
clocks (CLK, CLK), the feedback clocks (FBIN,FBIN), the 2.5V
LVCMOS input (PWRDWN) and the Analog Power input (AV
DD
).
When input PWRDWN is low while power is applied, the input
receivers are disabled, the PLL is turned off and the differential clock
outputs are 3-stated. When the AV
DD
is strapped low, the PLL is
turned off and bypassed for test purposes.
When the input frequency falls below a suggested detection fre-
quency that is below the operating frequency of the PLL, the device
will enter a low power mode. An input frequency detection circuit will
detect the low frequency condition and perform the same low power
features as when the PWRDWN input is low.
The PLL in the PI6CV857B clock driver uses the input clocks (CLK,
CLK) and the feedback clocks (FBIN,FBIN) to provide high-perfor-
mance, low-skew, low-jitter output differential clocks (Y[0:9], Y[0:9]).
The PI6CV857B is also able to track Spread Spectrum Clocking for
reduced EMI.
Product Features
• Operating Frequency up to 200 MHz and exceeds PC2700
RDIMM specification
• Distributes one differential clock input pair to ten differential
clock output pairs.
• Inputs (CLK,CLK) and (FBIN,FBIN): SSTL_2
• Input PWRDWN: LVCMOS
• Outputs (Yx, Yx), (FBOUT, FBOUT): SSTL_2
• External feedback pins (FBIN,FBIN) are used to
synchronize the outputs to the clock input.
• Operates at AV
DD
= 2.5V for core circuit and internal PLL,
and V
DDQ
= 2.5V for differential output drivers
• Packages (Pb-free and Green available):
- 48-pin TSSOP
Block Diagram
PI6CV857B
1:10 PLL Clock Driver for
2.5V DDR-SDRAM Memory
Y0
Y0
Y1
PWRDWN
AV
DD
FBIN
FBIN
CLK
CLK
PLL
Y1
Y2
Y2
Y3
Y3
Y4
Y4
Y5
Y5
Y6
Y6
Y7
Y7
Y8
Y8
Y9
Y9
FBOUT
FBOUT
Powerdown
and Test
Logic
V
DDQ
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
35
36
34
33
32
31
30
29
28
27
26
25
FBOUT
GND
GND
GND
FBIN
FBIN
PWRDWN
GND
GND
Y9
Y8
Y8
FBOUT
Y7
Y7
Y6
Y6
Y5
Y5
Y9
GND
GND
GND
Y0
Y0
Y1
Y1
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
GND
CLK
CLK
Y2
Y2
GND
Y3
Y3
Y4
Y4
AGND
AV
DD
Pin Configurations: 48-pin TSSOP (package code A)
