MAX863 Maxim, MAX863 Datasheet - Page 10

• Manufacturer Part Number: MAX863
• Description: Dual / High-Efficiency / PFM / Step-Up DC-DC Controller
• Manufacturer: Maxim

The MAX863 has two shutdown inputs useful for con-
serving power and extending battery life. Driving
SHDN1 or SHDN2 low turns off the corresponding DC-
DC controller and reduces quiescent current. Driving
both shutdown pins low turns off the reference, control,
and biasing circuitry, putting the MAX863 in a 1µA
shutdown mode. Connect SHDN1 and SHDN2 to V
for normal operation.
Boost DC-DC converters using the MAX863 can be
designed in a few simple steps to yield a working first-
iteration design. All designs should be prototyped and
Dual, High-Efficiency, PFM, Step-Up
DC-DC Controller
10
__________________Design Procedure
Figure 5a. Maximum Output Current vs. Input Voltage and
I PEAK (V
Figure 5c. Maximum Output Current vs. Input Voltage and
I PEAK (V
______________________________________________________________________________________
OUT
OUT
= 3.3V)
= 12V)
2.5
2.0
1.5
1.0
0.5
2.5
2.0
1.5
1.0
0.5
0
0
1.0
0
Cond: Single +5V
Cond: Single +5V
V
A: I
B: I
C: I
D: I
E: I
F: I
V
A: I
B: I
C: I
D: I
E: I
F: I
1.2
OUT
OUT
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
Code = FFFhex
Code = FFFhex
= 3.3V, L = 1.5 L
= 12V, L = 1.5 L
2
1.4
= 0.67A
= 0.5A
= 0.67A
= 0.5A
= 3A
= 2A
= 3A
= 2A
= 1.47A
= 1A
= 1.47A
= 1A
1.6
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
4
1.8
2.0
MIN
MIN
6
2.2
Shutdown Mode
2.4
8
2.6 2.8
10
A
B
C
D
E
F
A
B
C
D
E
F
3.0
12
DD
tested prior to production. Table 1 provides a list of
component suppliers.
Two design methods are included. The first uses
graphs for selecting the peak current required for 3.3V,
5V, 12V, and 24V outputs. The second uses equations
for selecting the peak current and inductor value in cir-
cuits with other outputs. When designing high-voltage,
flyback, SEPIC, and autotransformer boost circuits,
contact Maxim’s Applications Department for the
appropriate design equations.
For each of the two outputs, specify the output voltage
and maximum load current, as well as maximum and
Figure 5b. Maximum Output Current vs. Input Voltage and
I PEAK (V
Figure 5d. Maximum Output Current vs. Input Voltage and
I PEAK (V
OUT
OUT
= 5V)
= 24V)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
1.0
0
Cond: Single +5V
Cond: Single +5V
V
A: I
B: I
C: I
D: I
E: I
F: I
V
A: I
B: I
C: I
D: I
E: I
F: I
OUT
OUT
PEAK
PEAK
1.5
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
PEAK
Code = FFFhex
Code = FFFhex
2
= 5V, L = 1.5 L
= 24V, L = 1.5 L
Specify Design Objectives
= 3A
= 2A
= 0.67A
= 0.5A
= 3A
= 2A
= 0.67A
= 0.5A
= 1.47A
= 1A
= 1.47A
= 1A
2.0
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
4
2.5
MIN
MIN
6
3.0
8
3.5
10
4.0
A
B
C
D
E
F
A
C
E
F
B
D
4.5
12