LTC3538 Datasheet, PDF (13/16 Pages) Linear Technology – 800mA Synchronous Buck-Boost DC/DC Converter

LTC3538
OPERATION
Most applications demand an improved transient response
to allow a smaller output filter capacitor. To achieve a higher
bandwidth, Type III compensation is required, providing
two zeros to compensate for the double-pole response of
the output filter. Referring to Figure 5, the location of the
poles and zeros are given by:
ƒ_POLE1
≅
2•
π
•
1
32e³
•
R1• C_P1
Hz
(which is extremly close to DC)
ƒ _ZERO1
=
2•
π
1
•R_Z
•
C_P1
Hz
ƒ _ZERO2
=
2
•
π
1
• R1•
C_Z1
Hz
ƒ_POLE2
=
2•
π
1
•R_Z
•
C_P2
Hz
where resistance is in Ohms and capacitance is in
Farads.
V_OUT
1V
R1
C_Z1
FB
1
C_P2
R2
V_C
C_P1
RZ
2
3538 F05
Figure 5. Error Amplifier with Type III Compensation
3538fb
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