DS1080LU+ Maxim Integrated Products, DS1080LU+ Datasheet - Page 6

• Manufacturer Part Number: DS1080LU+
• Description: IC CRYSTAL MULT SS 8-USOP
• Manufacturer: Maxim Integrated Products
• Type: Crystal Multiplier, Spread Spectrum Clock Generatorr

Specifications of DS1080LU+

• Pll: Yes
• Input: Clock, Crystal
• Output: LVCMOS
• Number Of Circuits: 1
• Ratio - Input:output: 1:1
• Differential - Input:output: No/No
• Frequency - Max: 134MHz
• Divider/multiplier: No/Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Frequency-max: 134MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 1. Spread-Spectrum Frequency Modulation
Spread-Spectrum Crystal Multiplier
The DS1080L is a crystal multiplier with center spread-
spectrum capability. A 16MHz to 33.4MHz crystal is
connected to the X1 and X2 pins. Alternately, a 16MHz
to 33.4MHz clock can be applied to X1 in place of the
crystal. In such applications, X2 would be left open cir-
cuit. Using the CMSEL input, the user selects whether
the attached crystal or input clock is multiplied by 1, 2,
or 4. The DS1080L is capable of generating spread-
spectrum clocks from 16MHz to 134MHz.
The PLL can dither the output clock about its center fre-
quency at a user-selectable magnitude. Using the
SMSEL input, the user selects the dither magnitude.
The PDN input can be used to place the device into a
low-power standby mode where the SSO output is tri-
stated. If the PDN pin is floated, the SSO output is
active but the spread-spectrum dithering is disabled.
The spread-spectrum dither rate is fixed at f
keep the dither rate above the audio frequency range.
On power-up, the output clock (SSO) remains three-
stated until the PLL reaches a stable frequency (f
and dither (f
The DS1080L requires a parallel resonating crystal
operating in the fundamental mode, with an ESR of less
than 90Ω. The crystal should be placed very close to
the device to minimize excessive loading due to para-
sitic capacitances.
6
_______________________________________________________________________________________
DITHER
Applications Information
+1.5%
+1.0%
+0.5%
-0.5%
-1.0%
-1.5%
f
0
).
Detailed Description
Crystal Selection
IN
/ 1024 to
t
SSO
DITHER CYCLE RATE = f
)
When driving the DS1080L using an external oscillator
clock, consider the input (X1) to be high impedance.
The load capacitors C
on the crystal specifications (from the data sheet of the
crystal used). The crystal parallel load capacitance is
calculated as follows:
For the DS1080L use C
In this case, the equation then reduces to:
where C
Equation 2 is used to calculate the values of C
C
sheet electrical specifications.
To achieve best results, it is highly recommended that
a decoupling capacitor is used on the IC power-supply
pins. Typical values of decoupling capacitors are
0.001μF and 0.1μF. Use a high-quality, ceramic, sur-
face-mount capacitor, and mount it as close as possi-
ble to the V
inductance.
L2
based on values on C
DITHER
L1
= f
IN
= C
/1024
CC
C
L
L2
and GND pins of the IC to minimize lead
=
= C
C
L
C
C
Crystal Capacitor Selection
L
LX.
L
=
1
1
Power-Supply Decoupling
L1
L1
+
C
x C
2
LX
= C
and C
C
L
L
L
and C
2
2
+
L2
+
C
= C
L2
IN
C
IN
Oscillator Input
IN
are selected based
LX
noted in the data
.
Equati
Equation1
L1
o o n 2
and