Datasheet
AD5560 Data Sheet
Rev. D | Page 50 of 68
Table 21. Compensation Register 2
Address Default Data Bits, MSB First
0x5 0x0110 Bit Name Function
15
Manual
compensation
The AD5560 can be manually configured to compensate the force amplifier into a wide range of load
conditions. When this bit is high, manual compensation mode is active, and it overrides the settings of
Compensation Register 1. Readback when in manual compensation mode returns the compensation
settings loaded to the force amplifier and loaded to this register. Similarly, when in autocompensation
mode, readback of this register address returns the compensation settings of the force amplifier. However,
readback of this register address when in safe mode does not reflect
SAFEMODE
settings.
SAFEMODE
settings are g
m[1:0]
= 2, R
P
[2:0] = 0, R
Z[2:0]
= 0, C
C[3:1
] = 111, C
F[2:0]
= 5, and C
C0
= 1.
14
13
12
R
Z[2:0]
Set the value of R
Z
to add a zero at the following frequencies. This calculation assumes that C
C0
= 100 pF.
R
Z
R
Zx
(Ω) F
Z
(Hz)
0
1
500
3.2 M
1 1.6 k 1 M
2
5 k
320 k
3 16 k 100 k
4 50 k 32 k
5 160 k 10 k
6 500 k 3.2 k
7 1.6 M 1 k
11
10
9
R
P[2:0]
Set the value of R
P
to add an additional pole. There is an internal 8 pF capacitor to provide an RC filter,
creating a pole at one of the following frequencies.
R
P[2:0]
R
P
(Ω) F
P
(Hz)
0
1
200 100 M
1 675 29 M
2 2280 8.7 M
3 7700 2.6 M
4 26 k 760 k
5 88 k 220 k
6 296 k 67 k
7 1 M 20 k
8
7
g
m[1:0]
Set the transconductance of the force amplifiers input stage. The gain bandwidth (GBW) of the force
voltage loop is equal to g
mx
/C
C0
. The following values assume C
C0
= 100 pF.
g
mx
g
mx
(µA/V) GBW (Hz)
0 40 64 k
1 80 130 k
2
1
300 480 k (default)
3 900 1.3 M
6
5
4
C
F[2:0]
These bits determine which feedforward capacitor C
Fx
is switched in.
C
Fx
Action
0 None
1 C
F0
2 C
F1
3 C
F2
4 C
F3
5
1
C
F4
6 None
7 None
3 C
C3
Connect C
C3
in series with 100 kΩ
1
2
C
C2
Connect C
C2
in series with 25 kΩ
1
1 C
C1
Connect C
C1
in series with 6 kΩ
1
0 Reserved 0
1
This item corresponds to a
SAFEMODE
setting (
SAFEMODE
is the power-on default setting).