LMX25312820EVAL National Semiconductor, LMX25312820EVAL Datasheet - Page 6

• Manufacturer Part Number: LMX25312820EVAL
• Description: BOARD EVAL FOR LMX2531LQ 2820
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LMX25312820EVAL

• Main Purpose: Timing, Frequency Synthesizer
• Embedded: No
• Utilized Ic / Part: LMX2531LQ2820
• Primary Attributes: Low Band 1355 - 1462 MHz, High Band 2710 - 2925 MHz
• Secondary Attributes: 2.8 V ~ 3.2 V Supply
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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Ftest/LD
OSCin*
R2pLF
OSCin
Pin(s)
CPout
Vtune
Fout
CE
As with the CLK, DATA, and LE pins, level shifting may be required if the output voltage of the microcontroller is too high.
A resistive divider or a series diode are two ways to accomplish this. The diode has the advantage that no current flows
through it when the chip is powered down.
It is an option to use the lock detect information from this pin.
This is the high frequency output. This needs to be AC coupled, and matching may also be required. The value of the DC
blocking capacitor may be changed, depending on the output frequency.
In most cases, it is sufficient to short these together, although there always the option of adding additional poles. C1_LF,
C2_LF, and R2_LF are used in conjunction with the internal loop filter to make a fourth order loop filter.
This is the fastlock resistor, which can be useful in many cases, since the spurs are often better with low charge pump
currents, and the internal loop filter can be adjusted during fastlock.
This is the reference oscillator input pin. It needs to be AC coupled.
If the device is being driven single-ended, this pin needs to be shunted to ground with a capacitor.
Application Information
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