AK1590 Datasheet, PDF (21/36 Pages) Asahi Kasei Microsystems – 1GHz Delta-Sigma Fractional-N Frequency Synthesizer

10. Register Functional Description
< Address 1: Num >
D19 D18
D[17:0]
00
NUM[17:0]
Note) Writing into address 0x01 is enabled when writing into address 0x02 is performed.
NUM[17:0] : Set the numerator in 2’s complementary representation.
[AK1590]
Address
0001
< Address 2: Int >
D19 D18
D[17:15]
00
CP1[2:0]
D[14:0]
INT[14:0]
Address
0010
CP1[2:0]: Set the current value for the charge pump in normal operation (Charge Pump 1).
Charge Pump 1 current is determined by the following formula:
CP1_min = 0.57 / Resistance connected to [BIAS] pin
Charge Pump 1 current = CP1_min × ({CP1[2:0]} + 1)
D[17:15]
000
001
010
011
100
101
110
111
22kΩ
25.9
51.8
77.7
103.6
129.5
155.5
181.4
207.3
Charge Pump 1 current [A]
27kΩ
21.1
42.2
63.3
84.4
100.6
126.7
147.8
168.9
33kΩ
17.3
34.5
51.8
69.1
86.4
103.6
120.9
138.2
INT[14:0] : Set the integer.
When {PRE[1:0]} =”00”, P = 4 is selected and then an integer from 89 to 8191 can be set.
When {PRE[1:0]} =”01”, P = 8 is selected and then an integer from 201 to 16383 can be
set.
When {PRE[1:0]} =”10” or “11”, P = 16 is selected and then an integer from 521 to 32767
can be set.
MS1478-E-01
21
2013/2