ML4771
20µH
(Sumida CD75)
ML4771
V
PWR GND
NC
L1
IN
V
V
IN
GND
I
OUT
V
100µF
L2
V
SENSE
V
IN
OUT
200µF
259kΩ
268kΩ
Figure 1. Application Test Circuit.
I
L
1
6
V
V
L2
L1
V
R
IN
SENSE
2
Q2
A2
SYNCHRONOUS
RECTIFIER
START-UP
V
V
OUT
OUT
CONTROL
+
–
5
4
R1
R2
SENSE
A3
+
+
–
BOOST
CONTROL
–
Q1
2.57V
A1
I
SET
GND
PWR GND
3
8
Figure 2. PFM Regulator Block Diagram.
I
L(MAX)
I
I
SET
L
0
V
OUT
0
V
L2
Q1 ON
Q2 OFF
Q1 OFF
Q2 ON
Figure 3. Inductor Current andVoltage Waveforms.
4