LMX25311778EVAL National Semiconductor, LMX25311778EVAL Datasheet - Page 22

• Manufacturer Part Number: LMX25311778EVAL
• Manufacturer: National Semiconductor

Specifications of LMX25311778EVAL

• Lead Free Status / Rohs Status: Not Compliant

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2.2 REGISTER R1
2.2.1 NUM[21:12]
These are the MSB bits in for the fractional numerator that already have been described.
2.2.2 N[10:8] -- 3 MSB Bits for the N Counter
These are the 2 MSB bits for the N counter, which were discussed in the R0 register section.
2.2.3 ICP[3:0] -- Charge Pump Current
This bit programs the charge pump current when the charge pump gain. The current is programmable between 100 uA and 1.6
mA in 100 uA steps. In general, higher charge pump currents yield better phase noise for the PLL, but also can cause higher spurs.
ICP
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
Charge Pump State
10X
11X
12X
13X
14X
15X
16X
1X
2X
3X
4X
5X
6X
7X
8X
9X
22
Typical Charge Pump Current at 3 Volts
1080
1170
1260
1350
1440
(µA)
180
270
360
450
540
630
720
810
900
990
90