FS61857-01
AMERICAN MICROSYSTEMS, INC.
1:10 HSTL Zero-Delay Clock Buffer IC
Advance Information
November 2000
Figure 1: Block Diagram
1.0 Features
•
Generates one bank of ten differential 2.5V HSTL
clock outputs (YP0/YN0 to YP9/YN9) from one differ-
ential HSTL reference clock input
VDD
YP0
YN0
Power
PWRDWN#
Down
YP1
YN1
YP2
YN2
YP3
YN3
YP4
YN4
YP5
YN5
YP6
YN6
YP7
YN7
YP8
YN8
•
•
Meets the JEDEC Standard PLL Clock Driver for
AVDD
Registered DIMM Applications
External feedback input (FBINP/FBINN) to synchro-
nize all clock outputs to the reference input
Operating frequency 60MHz to 170MHz
FBINP
FBINN
PLL
•
•
•
CKP
CKN
Tight tracking skew (spread-spectrum tolerant)
Integrated 25Ω series damping resistors for driving
AGND
point-to-point loads
•
•
•
Auto power-down mode if reference input frequency
drops below 20MHz
YP9
YN9
Active-low power-down signal (PWRDWN#) tristates
all output drivers and disables the PLL
Packaged in a 48-pin TSSOP
FBOUTP
FBOUTN
GND
FS61857
2.0 Description
Figure 2: Pin Configuration
The FS61857 is a low skew, low jitter CMOS zero-delay
phase-lock loop (PLL) clock buffer IC. Ten differential
buffered clock outputs are derived from an onboard open-
loop PLL. The PLL aligns the frequency and phase of all
output clock pairs to the differential reference input clock
CLKP/CLKN, including a feedback output clock pair that
feeds back to FBINP/FBINN to close the loop. The PLL
can be bypassed for test purposes by pulling AVDD to
ground.
GND
YN0
YP0
VDD
YP1
YN1
GND
GND
YN2
1
2
3
4
5
6
7
8
9
48 GND
47 YN5
46 YP5
45 VDD
44 YP6
43 YN6
42 GND
41 GND
40 YN7
Table 1: Function Table
YP2 10
VDD 11
VDD 12
CKP 13
CKN 14
VDD 15
AVDD 16
AGND 17
GND 18
YN3 19
YP3 20
VDD 21
YP4 22
YN4 23
GND 24
39 YP7
38 VDD
37 PWRDWN#
36 FBINP
35 FBINN
34 VDD
33 FBOUTN
32 FBOUTP
31 GND
30 YN8
INPUT
OUTPUT
PLL
PWR
DWN#
YP0-
YP9
YN0- FBOUT FBOUT
AVDD
CKP CKN
YN9
P
N
2.5V
2.5V
2.5V
2.5V
GND
GND
GND
GND
-
L
L
H
H
L
L
H
L
H
L
H
L
H
H
L
H
L
H
L
H
L
Z
Z
L
H
Z
Z
L
Z
Z
H
L
Z
Z
H
L
Z
Z
L
H
Z
Z
L
Z
Z
H
L
Z
Z
H
L
OFF
Zero-
Delay
29 YP8
OFF
28 VDD
27 YP9
L
H
H
-
26 YN9
PLL
Bypass
25 GND
H
Z
H
Z
OFF
<20MHz
Z
Z
ISO9001
QS9000
This document contains information on a preproduction product. Specifications and information herein are subject to change without notice.
11.14.00