Dual, High-Efficiency, PFM, Step-Up
DC-DC Controller
A
B
C
20µs/div
a) IOUT1 = 287mA
20µs/div
b) IOUT1 = 608mA
20µs/div
c) IOUT1 = 767mA
OV
3.3V
0A
20µs/div
d) IOUT1 = 1.01A
A
VOUT1 = 3.3V
PLOTS a-d: INTERNAL FEEDBACK
PLOTS e-f: UNCOMPENSATED,
B
EXTERNAL FEEDBACK
A: MOSFET DRAIN, 2V/div
B: VOUT1, 100mV/div, 3.3V DC OFFSET
C: INDUCTOR CURRENT, 1A/div
C
20µs/div
e) IOUT1 = 757mA
Figures 3a–3f. MAX863 Switching Waveforms During Transition into Continuous Conduction
OV
3.3V
0A
20µs/div
f) IOUT1 = 881mA
VIN = 2.7V TO THE LOWER OF VOUT1 OR VOUT2
VOUT1 = 5V
C1
220µF
10V
≤0.1Ω
R5
D1
MBRS340T3
C3
L1
10µH
2A
100µF
10V
≤0.1Ω
C2
0.1µF
C4
100µF
10V
≤0.1Ω
L2
10µH
2A D2
MBRS340T3
SENSE1
VDD
N1.A
EXT1
EXT2
N1.B
IRF7301
CS1
CS2
1M
R7
100k
R1
50mΩ
R2
R3
50mΩ
1M
MAX863
1%
VOUT2 = 12V
C5
100µF
20V
≤0.1Ω
C6
10pF
LBO
FB2
LOW-BATTERY
DETECTOR OUTPUT
SHDN1
LBI
ON/OFF
R4
C8
SHDN2
115k
82pF
R6
REF
1%
C7
FB1 BOOT PGND GND
0.1µF
Figure 4a. Non-Bootstrapped Typical Operating Circuit
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