Detailed description, Pin description, Table 2 – Rainbow Electronics DS1081L User Manual
Page 4: Table 1
Detailed Description
The DS1081L modulates an input clock to generate a
center-dithered spread-spectrum output. A 20MHz to
134MHz clock is applied to the CLKIN pin. An internal
PLL dithers the output clock about its center frequency
at a user-selectable magnitude.
Spread-Spectrum Dither Magnitude
The DS1081L can generate dither magnitudes up to
±2%. The desired magnitude is selected using input pins
SMSEL1 and SMSEL2 as shown in Table 1.
Spread-Spectrum Dither Rate
The output spread-spectrum dither rate is determined
by the input frequency to maximize EMI reduction and
to ensure that the dither rate is always above the audio
frequency range. The user must configure CRSEL,
based on Table 2, depending on the input frequency
(f
IN
) so that the appropriate dither rate is programmed.
DS1081L
20MHz to 134MHz Spread-Spectrum
Clock Modulator for LCD Panels
4
_____________________________________________________________________
Pin Description
PIN NAME
FUNCTION
1
CLKIN
Clock Input. 20MHz to 134MHz clock input (f
IN
).
Spread-Spectrum Magnitude Select Inputs. These digital inputs select the desired spread-spectrum
magnitude as shown in the table below.
SMSEL2 SMSEL1
MAGNITUDE
SELECTED
2 SMSEL2
0 0
±2.0%
0 1
±1.5%
1 0
±1.0%
3
SMSEL1
1 1
±0.5%
4
GND Ground
5
SSEN
Spread-Spectrum Enable. Three-level input to enable/disable spread-spectrum and to tri-state the output.
0 = Power-up/spread-spectrum enabled.
Float = SSO tri-stated.
1 = Power-up/spread-spectrum disabled (not a bypass mode).
6 SSO
Spread-Spectrum Clock Output. Outputs a center-dithered spread-spectrum version of the clock input at
CLKIN.
Clock Range and Dither Rate Select. Three-level input that determines the dither rate. See the Detailed
Description section for details.
CRSEL
CLKIN RANGE
DITHER RATE
0
66MHz to 134MHz
f
IN
/2048
Float 33MHz
to
80MHz
f
IN
/1024
7 CRSEL
1 20MHz
to
38MHz
f
IN
/512
8
V
CC
Supply Voltage
CRSEL
CLKIN RANGE
DITHER RATE
0 66MHz
to
134MHz f
IN
/2048
Float 33MHz
to
80MHz
f
IN
/1024
1 20MHz
to
38MHz f
IN
/512
Table 2.
SMSEL2
SMSEL1
MAGNITUDE
0
0
±2.0%
0
1
±1.5%
1
0
±1.0%
1
1
±0.5%
Table 1.