MVPG30x/MVPG31
Datasheet
4.2
Switching Waveforms
NOTE: For repeatability of measuring output ripple (V
) for the BUCK regulator, the standard test
BUCK (P-P)
procedure limits the scope bandwidth to 20 MHz and uses a coax cable with very short leads
terminated into 50Ω. The coax leads must be routed away from the switching node as much as
possible.
Figure 23: Switching Waveforms—
Figure 24: Switching Waveforms—
DCM Mode
PWM Mode
V
SW
5V/DIV
V
5V/DIV
SW
I
IND
500 mA/DIV
5 mV/DIV
V
20 mV/DIV
BUCK
V
BUCK
I
IND
V
100 mV/DIV
500 mA/DIV
IN
500 ns/DIV
5.0 µs/DIV
V
V
= 5.0V
V
= 200.2 mV
V
= 5.0V
I
= 670.4 mA
IN
IN(P-P)
IND(P-P)
IND(PK)
IN
IND(PK)
= 1.2V
= 2.0A
I
I
= 601.5 mA
= 2.3A
V
= 1.2V
Freq = 185 kHz
BUCK
BUCK
I
I
= 50 mA
OUT
OUT
V
= 6.3 mV (Note)
Freq = 1 MHz
V
= 31.4 mV (Note)
OUT(P-P)
OUT(P-P)
Figure 25: PWM Output Ripple
Voltage
Figure 26: Switching Waveforms—
DCM Mode-Zoom
V
5V/DIV
SW
V
20 mV/DIV
20 mV/DIV
500 mA/DIV
BUCK
V
BUCK
I
IND
100 ms/DIV
500 ns/DIV
V
V
= 5.0V
I
= 2.0A
V
V
= 5.0V
I
= 50 mA
IN
OUT
IN
OUT
= 1.2V
V
= 15.7 mV (Note)
= 1.2V
BUCK
Ringing Freq = 10 MHz
BUCK
OUT(P-P)
Doc. No. MV-S102808-00 Rev. G
Page 36
Copyright © 2008 Marvell
April 14, 2008, 2.00
Document Classification: Proprietary
MARVELL [ MARVELL TECHNOLOGY GROUP LTD. ]
