Datasheet

Feedback loop calculation guidelines AN4164
24/38 Doc ID 023660 Rev 1
The mathematical expression of the compensator C(f) is:
Equation 5
where:
Equation 6
Equation 7
Equation 8
are chosen in order to censure the stability of the overall system. Gm = 2 mA/V (typical) is
the VIPER06 transconductance.
7.2 Compensation procedure
The first step is to choose the pole and zero of the compensator and the crossing frequency,
for instance:
– fZc = fp/2
– fPc = fz
– fcross = fcross_sel ≤ fsw/10
G1(fcross_sel) can be calculated from equation (
2 ) and, since by definition it is
| C(fcross_sel)*G1(fcross_sel)| = 1, C
0
, can be calculated as follows:
Equation 9
()
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛⋅
+⋅⋅⋅⋅
⋅
+
⋅=
Δ
Δ
=
fPc
jf
jf
fZc
jf
H
C
V
I
fC
COM POUT
12
1
0
pk
π
Rf bHRf bL
Rf bL
CpCc
Gm
Co
+
⋅
+
−=
CcRc
fZc
⋅⋅⋅
=
π 2
1
CpCcRc
CpCc
fPc
⋅⋅⋅⋅
+
=
π 2
)_(1
_
1
_
1_2
0
selfcrossG
H
fZc
jselfcross
fPc
jselfcross
jself cross
C
COM P
⋅
⋅
+
⋅
+⋅⋅⋅⋅
=
π