MAX730A Ver la hoja de datos (PDF) - Maxim Integrated
Número de pieza
componentes Descripción
Fabricante
MAX730A Datasheet PDF : 16 Pages
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5V, Step-Down,
Current-Mode PWM DC-DC Converters
Table 1. Typical Soft-Start Times
R1 (kΩ)
510
510
510
510
510
510
510
None
None
None
None
None
None
MAX730A CIRCUIT CONDITIONS
V+ (V)
6
IOUT (mA)
0
C4 (µF)
100
9
0
100
11
0
100
9
150
100
9
300
100
9
150
390
9
150
680
6
0
100
9
0
100
11
0
100
9
150
100
9
150
390
9
150
680
C1 = 0.01
2
1
1
1
1
3
4
16
10
8
34
39
40
SOFT-START TIME (ms) vs. C1 (µF)
C1 = 0.047
C1 = 0.1
C1 = 0.47
6
11
28
4
6
15
2
4
11
4
8
21
5
9
27
6
9
23
6
9
24
34
51
125
22
34
82
18
28
66
134
270
1263
147
280
1275
152
285
1280
MAX738A/MAX744A CIRCUIT CONDITIONS
R1 (kΩ)
510
V+ (V)
7
IOUT (mA)
0
C4 (µF)
100
510
12
0
100
510
16
0
100
510
12
300
100
510
12
750
100
None
7
0
100
None
12
0
100
None
16
0
100
None
12
300
100
C1 = 0.01
1
1
1
1
1
12
7
6
27
SOFT-START TIME (ms) vs. C1 (µF)
C1 = 0.047
C1 = 0.1
C1 = 0.47
4
6
18
2
3
8
1
2
6
3
5
3
5
8
21
27
40
100
16
25
54
13
20
68
112
215
1114
Internal Reference
The +1.23V bandgap reference supplies up to 100µA
at REF. Connect a 0.01µF bypass capacitor from REF
to GND.
Oscillator
The internal oscillator of the MAX730A typically oper-
ates at 170kHz (160kHz for the MAX738A and 185kHz
for the MAX744A). The MAX744A is guaranteed to
operate at a minimum of 159kHz and a maximum of
212.5kHz over the operating voltage and temperature
range, making it ideal for use in portable communica-
tions systems. The Typical Operating Characteristics
graphs indicate oscillator frequency stability over tem-
perature and supply voltage.
____________Applications Information
Figure 3 shows the standard 5V step-down application
circuits. Table 3 lists the components for the desired
operating temperature range. These circuits are useful
in systems that require high current at high efficiency
and are powered by an unregulated supply, such as a
battery or wall-plug AC-DC transformer. These circuits
operate over the entire line, load, and temperature
ranges using the single set of component values shown
in Figure 3 and listed in Table 3.
Inductor Selection
The MAX730A/MAX738A/MAX744A require no inductor
design because they are tested in-circuit, and are
guaranteed to deliver the power specified in the
Electrical Characteristics with high efficiency using a
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