MIC4681_05 Datasheet, PDF (9/16 Pages) Micrel Semiconductor – 2A-Peak SuperSwitcher SOP-8 Buck Regulator

MIC4681
Micrel
Bode Plots
The following bode plots show that the MIC4681 is stable over all conditions using a 68µF inductor (L) and a 220µF output
capacitor (C_OUT). To assure stability, it is a good practice to maintain a phase margin of greater than 35°.
No-Load Stability
Phase Margin = 94°
Full-Load Stability
Phase Margin = 74°
L = 68µF
C_OUT = 220µF
L = 68µF
C_OUT = 220µF
V_IN = 7V
V_OUT = 5.0V
I_OUT = 0A
Amb = 22°C
No-Load Stability
Phase Margin = 102°
L = 68µF
C_OUT = 220µF
V_IN = 7V
V_OUT = 5.0V
I_OUT = 1.1A
Amb = 22°C
Full-Load Stability
Phase Margin = 53°
L = 68µF
C_OUT = 220µF
V_IN = 12V
V_OUT = 5.0V
I_OUT = 0A
Amb = 22°C
No-Load Stability
Phase Margin = 118°
L = 68µF
C_OUT = 220µF
V_IN = 30V
V_OUT = 5.0V
I_OUT = 0A
Amb = 22°C
V_IN = 12V
V_OUT = 5.0V
I_OUT = 1.4A
Amb = 22°C
Full-Load Stability
Phase Margin = 59°
L = 68µF
C_OUT = 220µF
V_IN = 30V
V_OUT = 5.0V
I_OUT = 1.1A
Amb = 22°C
April 2005
9
MIC4681