Low-Jitter I2C/SPI Programmable Dual LVPECL Oscillator
DSC2122 DSC2222
Pin Description
Pin No. Pin Name Pin Type
Description
Enables outputs when high and disables when low
Leave unconnected or grounded
DSC2122: Leave unconnected or grounded
DSC2222: Serial clock from master
Ground
1
2
Enable
NC
NC
SCLK
GND
SDA
MOSI
SCL
MISO
CS_bar
SS
I
NA
NA
I
Power
I
3
4
5
DSC2122: I2C Serial Data
DSC2222: SPI Serial Data from Master to Slave
I
O
I
I
DSC2122: I2C Serial Clock
6
7
DSC2222: SPI Serial Data from Slave to Master
DSC2122: I2C Chip Select (Active Low)
DSC2222: SPI Slave Select (Active Low)
Positive LVPECL Output 1
Negative LVPECL Output 1
Negative LVPECL Output 2
Positive LVPECL Output 2
Power Supply for LVPECL Output 2
Power Supply
8
9
Output1+
Output1-
Output 2-
Output 2+
VDD2
VDD
O
O
O
10
11
12
13
14
O
Power
Power
I
FS
Default output clock frequency bit
Operational Description
The DSC2122/2222 is a dual LVPECL oscillator
consisting of a MEMS resonator and a support
PLL IC. The outputs are generated through
independent 8-bit programmable dividers from
the output of the internal PLL.
control pin (FS) selects the initial pair. Once
the device is powered up, a new output
frequency
pair
can
be
programmed.
Programming details are provided in the
Programming Guide. Standard default
frequency pairs are described in the following
sections. Discera supports customer defined
versions of the DSC2122/2222.
DSC2122/2222 allows for easy programming
of the output frequencies using I2C/SPI
interface. Upon power-up, the initial output
frequencies are controlled by an internal pre-
programmed memory (OTP). This memory
stores all coefficients required by the PLL for
two different default frequency pairs. The
When Enable (pin 1) is floated or connected to
VDD, the DSC2122/2222 is in operational
mode. Driving Enable to ground will tri-state
both output drivers (hi-impedance mode).
Output Clock Frequencies
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DSC2122 DSC2222
Page 2
MK-Q-B-P-D-12050105
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