mb3775pfv Fujitsu Microelectronics, Inc., mb3775pfv Datasheet - Page 19

• Manufacturer Part Number: mb3775pfv
• Description: Switching Regulator Controller
• Manufacturer: Fujitsu Microelectronics, Inc.

2.
The equivalent series resistance (ESR) of the smoothing capacitor in the DC/DC converter greatly affects the
loop phase characteristic.
A smoothing capacitor with a low ESR reduces system stability by increasing the phase shift in the high-frequency
region (see Fig. 30). Therefore, a smoothing capacitor with a high ESR will improve system stability. Be careful
when using low ESR semiconductor electrolytic capacitors (OS-CON) and tantalum capacitors.
Effect of equivalent series resistance of smoothing capacitor
20
0
20
40
60
10
(1)
(2)
: R
: R
V
IN
C
C
= 0
= 31 m
100
Fig. 30 - Gain vs. Frequency
Frequency f (Hz)
1k
Fig. 29 - Step Down DC/DC Converter Basic Circuit
Tr
10k
(1)
(2)
D
100k
L
180
0
90
10
C
(1)
(2)
: R
: R
Fig. 31 - Phase vs. Frequency
C
C
= 0
= 31 m
R
100
C
Frequency f (Hz)
1k
R
L
10k
MB3775
(1)
(2)
100k
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