SL2309
General Description
Select Input Control
The SL2309 is a low skew, low jitter Zero Delay Buffer with
very low operating current.
The SL2309 provides two (2) input select control pins
called S1 (Pin-9) and S2 (Pin-8). This feature enables
users to select various states of output clock banks-A and
bank-B, output source and PLL shutdown features as
shown in the Table 2.
The product includes an on-chip high performance PLL
that locks into the input reference clock and produces nine
(9) output clock drivers tracking the input reference clock
for systems requiring clock distribution.
The S1 (Pin-9) and S2 (Pin-8) inputs include 250 kȍ weak
pull-up resistors to VDD.
in addition to CLKOUT that is used for internal PLL
feedback, there are two (2) banks with four (4) outputs in
each bank, bringing the number of total available output
clocks to nine (9).
PLL Bypass Mode
If the S1 and S2 pins are logic Low(0) and High(1)
respectively, the on-chip PLL is shutdown and bypassed,
and all the nine output clocks bank A, bank B and
CLKOUT clocks are driven by directly from the reference
input clock. In this operation mode SL2309 works like a
non-ZDB fanout buffer. In this operation mode the input
power-down detection circuit is disabled and outputs
follow the input clock from DC to rated frequencies based
on drive levels and load specifications.
Input and Output Frequency Range
The input and output frequency range is the same. But, it
depends on the drive and CL levels as given in the below
Table 1.
Drive
CL(pF)
Min(MHz)
Max(MHz)
HIGH
15
10
140
High and Low-Drive Product Options
HIGH
LOW
LOW
30
15
30
10
10
10
100
100
66
The SL2309 is offered with High Drive “-1H” and Standard
Drive “-1” options. These drive options enable the users
to control load levels, frequency range and EMI. Refer to
the switching electrical tables for the details.
Table 1. Input/Output Frequency Range
Skew and Zero Delay
If the input clock is DC (GND to VDD) or floating, this is
detected by an input frequency detection circuitry and all
nine (9) clock outputs are forced to Hi-Z. The PLL is
shutdown to save power. In this shutdown state, the
product draws less than 12ȝA-max supply current.
All outputs should drive the similar load to achieve the
output-to-output skew and input-to-output specifications
given in the switching electrical tables. However, Zero
Delay between input and outputs can be adjusted by
changing the loading at CLKOUT relative to the banks A
and B clocks since CLKOUT is the feedback to the PLL.
In PLL by-pass mode (S2=1 and S1=0), the detection
circuit is disabled and input frequency range is 10 to
100MHz for standard (-1) drive and 10 to 140MHz for high
(-1H) drive.
Power Supply Range (VDD)
The SL2309 is designed to operate at VDD=3.3V (+/-
10%). An internal on-chip voltage regulator is used to
provide PLL constant power supply of 1.8V, leading to a
consistent and stable PLL electrical performance in terms
of skew, jitter and power dissipation.
SpreadThru™ Feature
If a Spread Spectrum Clock (SSC) were to be used as an
input clock, the SL2309 is designed to pass the
modulated Spread Spectrum Clock (SSC) signal from its
reference input to the output clocks. The same spread
characteristics at the input are passed through the PLL
and drivers without any degradation in spread percent
(%), spread profile and modulation frequency
Refer to SL23EP09 for 3.3V to 2.5V and SL23EPL09 for
1.8V power supply operations.
Rev 1.1, May 29, 2007
Page 3 of 12
SPECTRALINEAR [ SPECTRALINEAR INC ]
