Datasheet

Data Sheet AD5560
Rev. D | Page 49 of 68
The AD5560 has three compensation modes. The power-on default mode is
SAFEMODE
enabled. This ensures that the device is stable
into any load. Use Compensation Register 1 to configure the device for autocompensation, where the user inputs the CDUT and ESR
bits, and the AD5560 chooses the most appropriate compensation scheme for these load conditions.
Table 20. Compensation Register 1
Address Default Data Bits, MSB First
0x4 0x0000 Bit Name Function
15
14
13
12
CDUT[3:0] Use these control bits to tell the device how much capacitive load there is so that the device can
optimize the compensation used. Do not overestimate CDUT because this can cause oscillations.
Underestimating CDUT gives suboptimal but stable performance.
CDUT CDUT Min CDUT Max
0 0 nF 50 nF
1
50 nF
83 nF
2 83 nF 138 nF
3 138 nF 229 nF
4 229 nF 380 nF
5 380 nF 630 nF
6 630 nF 1.1 µF
7 1.1 µF 1.7 µF
8 1.7 µF 2.9 µF
9
2.9 µF
4.8 µF
10 4.8 µF 7.9 µF
11 7.9 µF 13 µF
12 13 µF 22 µF
13 22 µF 36 µF
14 36 µF 60 µF
15 60 µF 160 µF
11
10
9
8
ESR[3:0] Use these control bits to tell the device how much ESR there is in series with CDUT so that the device can
optimize the compensation used. Do not underestimate ESR because this can cause oscillations.
Overestimating ESR gives suboptimal but stable performance.
ESR ESR Min ESR Max
0
0 mΩ
1 mΩ
1 1 mΩ 1.8 mΩ
2 1.8 mΩ 3.4 mΩ
3 3.4 mΩ 6.3 mΩ
4 6.3 mΩ 12 mΩ
5 12 mΩ 21 mΩ
6 21 mΩ 40 mΩ
7 40 mΩ 74 mΩ
8
74 mΩ
140 mΩ
9
140 mΩ
250 mΩ
10 250 mΩ 460 mΩ
11 460 mΩ 860 mΩ
12 860 mΩ 1500 mΩ
13 1500 mΩ 2900 mΩ
14 2900 mΩ 5400 mΩ
15 6400 mΩ 10,000 mΩ
7
SAFEMODE
SAFEMODE
= 0 overrides values in Compensation Register 1 to make the force amplifier stable under
most load conditions. This mode is useful if it is unknown what the DPS is driving, but it does result in an
extremely slow response. The default operation on power-on or reset is
SAFEMODE
.
SAFEMODE
settings are always 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.
Set this bit high to enable autocompensation.
6:0 Reserved Set to 0.