SI5XX-EVB Datasheet, PDF (2/8 Pages) Silicon Laboratories – EVALUATION BOARD FOR Si53X XOS AND Si55X VCXOS

Si5xx-EVB
1. Functional Description
The Si5xx-EVB provides access to all signals for
configuring and operating the device. This board allows
evaluation of the Si55x VCXO device either by itself
(open-loop) or within a prototype PLL (closed-loop). The
performance of the Si53x XO device can also be
evaluated on this board (the Vc port is not used for XO
devices).
Table 1. Jumper Control
Part Type JP1
JP2
JP3
JP4
Si530
N/A
N/A
OE
N/A
Si532
N/A
N/A
OE Freq Sel
Si534 Freq Sel1 Freq Sel2 OE
N/A
Si550
N/A
N/A
OE
V_C
Si552
N/A
N/A Freq Sel V_C
Si554 Freq Sel1 Freq Sel2 OE
V_C
Notes:
1. With jumper(s) installed, signal(s) are driven low.
2. With jumper(s) not installed, signal(s) are pulled high.
1.1. Power Supply
The Si55x/Si53x devices support operation from
nominal voltages of 1.8, 2.5, and 3.3 V. Review the
device data sheet and part number for allowed
configurations of output buffer type and device power
supply.
1.2. Voltage Control for VCXOs
The voltage control (V_C) input of the Si55x device is
conveniently accessible through an SMA jack (J3) but
can also be driven (and observed) through 100 mil-
centered posts (JP4). For prototyping purposes, two
0603 solder pads are located near the device V_C input
(R3 and C3). A traditional PLL might use these as a
single-time-constant low-pass filter (RC filter). The EVB
is shipped with a 0 Ω resistor soldered at R3; C3 is left
open. The voltage control input is not used for XO
devices.
1.3. Output Clock
Because the Si55x/Si53x devices can support an
LVPECL buffer type (in addition to LVDS and CMOS),
pulldown resistors (R1 and R2) are available for proper
output biasing. For LVPECL buffers, biasing can be
achieved through a variety of equivalent circuits; the
Si5xx-EVB allows for 130 Ω pulldown resistors. After
the output biasing, the high-speed outputs are dc-
blocked for connection to differently biased inputs, such
as standard test equipment or a phase detector EVB.
Please review “1.4. Preparing the EVB” for non-LVPECL
devices.
1.4. Preparing the EVB
By default, the evaluation board is set up to accept
LVPECL configured devices. This configuration uses
130 Ω pull-down resistors to bias the LVPECL output
stage. If an LVDS, CMOS, or CML based device is to
be installed, the output biasing resistors, R1 and R2,
should be removed.
2
Rev. 0.14