Datasheet

LMX2541SQ2060E, LMX2541SQ2380E
LMX2541SQ2690E, LMX2541SQ3030E
LMX2541SQ3320E, LMX2541SQ3740E
www.ti.com SNOSB31I –JULY 2009–REVISED FEBRUARY 2013
Register R7
Although Register 7 has no elective bits to program, it is very important to program this register because the
action of doing so with the bit sequence shown in the register map resets all the registers, including hidden
registers with test bits that are not disclosed. Register 7 should always be programmed first, because it will reset
all other programming information. The register reset occurs only after the LE signal has transitioned from low to
high and back to low again.
Register R13
This register needs to be programmed only in the event that the RFout pin is being used and VCO_DIV = 1.
VCO_DIV_OPT[2:0]
This word optimizes the RFout power level based on the VCO_DIV and VCO_GAIN words.
Condition VCO_DIV_OPT Comments
RFout Pin Disabled
OR
Register R13 Does Not need to be
VCO_DIV>1 0
programmed, since 0 is the default.
OR
VCO_GAIN<13
RFout Pin Enabled
AND
4
VCO_DIV=1
VCO_GAIN>12
Register R12
This register needs to be programmed as shown in the register map in the event that the internal VCO is being
used. When using external VCO mode, this register does not need to be programmed.
Register R9
Program this register as shown in the register map.
Register R8
AC_TEMP_COMP[4:0]
This word optimizes the VCO phase noise for possible temperature drift. When the VCO frequency is changed,
the internal tuning algorithm optimizes the phase noise for the current temperature. In fixed frequency
applications, temperature drift may lead to sub-optimal phase noise over time. In dynamic frequency applications,
the re-tuning of the VCO frequency overcomes this problem because the phase noise is re-optimized each time
the VCO frequency is changed. The AC_TEMP_COMP word can be used to optimize the VCO phase noise for
temperature drift for these different scenarios. The following table indicates which values of this word should be
used for each scenario.
AC_TEMP_COMP Application Type
5 Dynamic Frequency
24 Fixed Frequency
All Other States Invalid
Register R6
Register R6 has words that impact the output power of the RFout pin.
RFOUT[1:0] - RFout enable pin
This word works in combination with the RFoutEN Pin to control the state of the RFout pin.
RFOUT RFoutEN Pin RFout Pin State
0 Don't Care Disabled
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Product Folder Links: LMX2541SQ2060E LMX2541SQ2380E LMX2541SQ2690E LMX2541SQ3030E
LMX2541SQ3320E LMX2541SQ3740E