LMX2541SQ2060E/NOPB National Semiconductor, LMX2541SQ2060E/NOPB Datasheet - Page 51

• Manufacturer Part Number: LMX2541SQ2060E/NOPB
• Description: IC PLL FREQ SYNTH W/VCO 36LLP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: Clock/Frequency Synthesizer (RF)r

Specifications of LMX2541SQ2060E/NOPB

• Pll: Yes
• Input: Clock
• Output: Clock
• Number Of Circuits: 1
• Ratio - Input:output: 2:2
• Differential - Input:output: No/No
• Frequency - Max: 2.24GHz
• Divider/multiplier: Yes/No
• Voltage - Supply: 3.15 V ~ 3.45 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 36-LLP
• Frequency-max: 2.24GHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LMX2541SQ2060E

For both of the able connection diagrams, L1, L2, and Lmid
should be left open, but the pads should be placed on these
pins for optimal solderability. The GND pins should have sep-
arate vias to ground and the GND DAP also needs to be
grounded with 9 vias. The VccVCO, VccRFout, and VccDiv
pins can be shorted to the power plane, but need to be con-
nected. For the other Vcc pins, ferrite beads and bypass
capacitors may be added in order to improve spurious per-
formance. VregVCO and VrefVCO need to be connected
even if the internal VCO is not being used. The VregRFout
pin only needs to be connected if the RFout pin is being used.
When a block is not used, it is always still necessary to con-
nect the corresponding Vcc pin, but the bypassing is not
necessary, as shown in the above diagram for the external
VCO mode.
External VCO Mode, Single-Ended OSCin, RFout Pin not Used
51
3.1.1 OSCin/OSCin* Connections
For single-ended operation, the signal is driven into the OS-
Cin pin. The OSCin* pin is terminated the same as the OSCin
pin. This is a typical case if the device is driven by a TCXO.
For both single-ended and differential operation, the input is
AC coupled because the OSCin/OSCin* pins self-bias to an
optimal DC operating point. Better performance for both
phase noise and fractional spurs is obtained for signals with
a higher slew rate, such as a square wave. This is especially
important for lower frequency signals, since slower frequency
sine waves have lower slew rates. Fractional spurs are typi-
cally about four dB better when running in differential mode
as opposed to single-ended mode.
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