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Part Number: LMX2571
I'm using the LMX2571 with an external VCXO and I'm a little confused by the Register description in the data sheet for setting the charge pump current. (R42 bits 0-4 and R41 bits 7-11)The description shows:0=Tristate2=312.5 uA4= 625 uA
If you increment by 312.5 uA you reach 3437.5 uA at a register value of 22. Should the max current be 4687.5 uA or are there additional states not shown. Also these increment values are not what i find in the Kpd pull down menu on PLLatinum Sim. I find a similar issue with the charge pump setting for the internal VCO.
This is the full decode. So as you suspected, there are intermediate values, note setting 16. This values come from the TICS Pro GUI software for programming the LMX2571.
* I will note the need for updating the datasheet.
Thanks for your feedback.
0 = Tri-state 1 = Reserved 2 = 312.5 uA 3 = Reserved 4 = 625 uA 5 = Reserved 6 = 937.5 uA 7 = Reserved 8 = 1250 uA 9 = Reserved10 = 1562.5 uA11 = Reserved12 = 1875 uA13 = Reserved14 = 2187.5 uA15 = Reserved16 = 1250 uA17 = Reserved18 = 1562.5 uA19 = Reserved20 = 1875 uA21 = Reserved22 = 2187.5 uA23 = Reserved24 = 2500 uA25 = Reserved26 = 2812.5 uA27 = Reserved28 = 3125 uA29 = Reserved30 = 3437.5 uA31 = Reserved
Here is the decode for the internal CP, it is the same as above, except has the odd values filled in.
0=Tri-state 1=156.25 uA 2=312.5 uA 3=468.8 uA 4=625 uA 5=781.3 uA 6=937.5 uA 7=1093.8 uA 8=1250 uA 9=1406.3 uA10=1562.5 uA11=1718.8 uA12=1875 uA13=2031.3 uA14=2187.5 uA15=2343.8 uA16=1250 uA17=1406.3 uA18=1562.5 uA19=1718.8 uA20=1875 uA21=2031.3 uA22=2187.5 uA23=2343.8 uA24=2500 uA25=2656.3 uA26=2812.5 uA27=2968.8 uA28=3125 uA29=3281.3 uA30=3437.5 uA31=3593.8 uA
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