MIC4681
Micrel
Bode Plots
The following bode plots show that the MIC4681 is stable over all conditions using a
68
µ
F inductor
(L) and a
220
µ
F 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
V
IN
= 7V
V
OUT
= 5.0V
I
OUT
= 1.1A
Amb = 22°C
No-Load Stability
Phase Margin = 102°
Full-Load Stability
Phase Margin = 53°
L = 68µF
C
OUT
= 220µF
L = 68µF
C
OUT
= 220µF
V
IN
= 12V
V
OUT
= 5.0V
I
OUT
= 0A
Amb = 22°C
V
IN
= 12V
V
OUT
= 5.0V
I
OUT
= 1.4A
Amb = 22°C
No-Load Stability
Phase Margin = 118°
Full-Load Stability
Phase Margin = 59°
L = 68µF
C
OUT
= 220µF
L = 68µF
C
OUT
= 220µF
V
IN
= 30V
V
OUT
= 5.0V
I
OUT
= 0A
Amb = 22°C
V
IN
= 30V
V
OUT
= 5.0V
I
OUT
= 1.1A
Amb = 22°C
February 2001
9
MIC4681
MICREL [ MICREL SEMICONDUCTOR ]
