LMX2485E EVAL National Semiconductor, LMX2485E EVAL Datasheet - Page 19

• Manufacturer Part Number: LMX2485E EVAL
• Description: BOARD EVALUATION LMX2485E
• Manufacturer: National Semiconductor
• Series: PLLatinum™r

Specifications of LMX2485E EVAL

• Main Purpose: Timing, Frequency Synthesizer
• Utilized Ic / Part: LMX2485E
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

HYBRID VCO FOOTPRINT
Although the evaluation board is created to support a particular VCO, the footprint is flexible and designed such
that other VCOs are easy to put on the board. To mount a smaller VCO on the board, scratch off the solder
mask with the flat edge of a screwdriver and then put solder on the pads such that it covers the exposed
copper.
TEST POINTS
BANDSWITCH VCO SUPPORT
The board is also configured so that CodeLoader can control a bandswitch VCO for either the RF or IF PLL. In
order to do this, one can use the trigger pin. Don’t forget to stuff the components on the bottom layer for the
bandswitch option.
COMPONENT OPTIONS
Some components have a 'p' suffix to denote it as an option. These usually have shared footprints and can not
both be stuffed. Below is a list of these options.
C2_RF &
C2pRF
R2_RF &
R2pRF
R26 & R26p
Component
These components both add in parallel. There are 2 footprints here to allow for different
sizes of capacitors
During Fastlock, the chip switches R2pRF in parallel with R2_RF
For normal operation R26p should be open. However, for sensitivity measurements 68 Ω
may be placed in R26p and R26 can be removed in order to form a 6 dB T-Pad.
Additional Features of the LMX2485E Evaluation Board
Test Point
TRIG
TP1
TP2
TP3
TP4
L M X 2 4 8 5 E
E V A L U A T I O N
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Option
B O A R D
RF Charge Pump voltage
RF Fastlock output
Microwire trigger
Ftest/LD output
O P E R A T I N G
OSCout pin
Function
I N S T R U C T I O N S