Datasheet
Data Sheet AD9558
Rev. B | Page 79 of 104
Table 63. Base Digital Loop Filter with Normal Phase Margin (PM = 70°, BW = 0.1 Hz, Third Pole Frequency = 2 Hz, N1 = 1)
1
Address Bits Bit Name Description
0x0323 [7:0] NPM Alpha-0 linear Alpha-0 coefficient linear, Bits[7:0]
0x0324
[7:0]
Alpha-0 coefficient linear, Bits[15:8]
0x0325 7 Reserved Reserved
[6:0]
NPM Alpha-1 exponent Alpha-1 coefficient exponent, Bits[6:0]
0x0326
[7:0] NPM Beta-0 linear Beta-0 coefficient linear, Bits[7:0]
0x0327
[7:0] Beta-0 coefficient linear, Bits[15:8]
0x0328
7 Reserved Reserved
[6:0] NPM Beta-1 exponent Beta-1 coefficient exponent, Bits[6:0]
0x0329
[7:0] NPM Gamma-0 linear Gamma-0 coefficient linear, Bits[7:0]
0x032A
[7:0] Gamma-0 coefficient linear, Bits[15:8]
0x032B
7 Reserved Reserved
[6:0] NPM Gamma-1 exponent Gamma-1 coefficient exponent, Bits[6:0]
0x032C
[7:0] NPM Delta-0 linear Delta-0 coefficient linear, Bits[7:0]
0x032D
[7:0] Delta-0 coefficient linear, Bits[15:8]
0x032E
7 Reserved Reserved
[6:0] NPM Delta-1 exponent Delta-1 coefficient exponent, Bits[6:0]
1
Note that the digital loop filter base coefficients (α, β, γ, and δ) have the following general form: x(2
y
), where x is the linear component and y is the exponential
component of the coefficient. The value of the linear component (x) constitutes a fraction, where 0 ≤ x ≤ 1. The exponential component (y) is a signed integer.
OUTPUT PLL CONFIGURATION (REGISTER 0x0400 TO REGISTER 0x0408)
Table 64. Output PLL Setting
1
Address Bits Bit Name Description
0x0400
[7:0]
Output PLL (APLL)
charge pump current
LSB = 3.5 µA
00000001b = 1 × LSB; 00000010b = 2 × LSB; 11111111b = 255 × LSB
Default: 0x81 = 451 µA CP current
0x0401
[7:0] APLL N divider Division = 14 to 255
Default: 0x14 = divide-by-20
0x0402
[7:0] Reserved Reserved; default: 0x00
0x0403
[7:6] APLL loop filter control Pole 2 resistor Rp2; default: 0x07
Rp2 (Ω)
Bit 7
Bit 6
500 (default) 0 0
333
0
1
250 1 0
200 1 1
[5:3]
Zero resistor, Rzero
Rzero (Ω) Bit 5 Bit 4 Bit 3
1500 (default)
0
0
0
1250 0 0 1
1000 0 1 0
930 0 1 1
1250 1 0 0
1000 1 0 1
750 1 1 0
680 1 1 1