MAX763ACSA Datasheet Download

Part No.:
MAX763ACSA
Download:
Download Datasheet
Description:
[3.3V, Step-Down, Current-Mode PWM DC-DC Converters]
File Size:
136 K
Page:
12 Pages
Logo:
Manufacturer:
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
PCB Prototype
 MAX763ACSA Datasheet Page:4MAX763ACSA Datasheet Page:5MAX763ACSA Datasheet Page:6MAX763ACSA Datasheet Page:7MAX763ACSA Datasheet Page:8MAX763ACSA Datasheet Page:10MAX763ACSA Datasheet Page:11MAX763ACSA Datasheet Page:12 
3.3V, Step-Down,
Current-Mode PWM DC-DC Converters
MAX748A/MAX763A
INPUT
MAX748A 3.3V TO 16.0V
V
MAX763A 3.3V TO 11.0V
IN
8
1
V+
SHDN
LX
7
D1
1N5817
L1
22µH
OUTPUT
3.3V
C5
330pF
C4
150µF
OPTIONAL 21kHz LOWPASS OUTPUT FILTER
C2
1.0µF
C3
150µF
MAX748A
MAX763A
OUT
5
L2
25µH
OUTPUT
C7
2.2µF
FILTER
OUTPUT
3
SS
CC
4
C1
0.047µF
GND
6
2
REF
C6
1000pF
Figure 3. Standard 3.3V Step-Down Application Circuit Using Through-Hole Components (commercial temperture range)
Table 2. Component Table for
Wide Temperature Applications
C1(µF) C2(µF) C3(µF) C4(µF) C5(pF) C6(pF) L1(µH)
Through-
Hole
0.047
SO
0.047
1.0
1.0
150*
68**
220*
100***
330
330
1000
1000
22
22
* Sanyo OS-CON Series (very low ESR)
** 16V or greater maximum voltage rating.
*** 6.3V or greater maximum voltage rating.
input voltages of 4.75V to 16V with 800mA typical out-
put currents. The MAX763A delivers a guaranteed
300mA for input voltages of 4V to 11V, a guaranteed
500mA for input voltages of 4.75V to 11V, and has
700mA typical output currents. The MAX748A/
MAX763A operate from an input down to 3V (the upper
limit of undervoltage lockout), but with some reduction
in output voltage and maximum output current.
Inductor Selection
The MAX748A/MAX763A 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 single
22µH inductor. The 22µH inductor’s incremental satu-
ration current rating should be greater than 1A for
500mA load operation. Table 3 lists inductor types and
suppliers for various applications. The surface-mount
inductors have nearly equivalent efficiencies to the
larger through-hole inductors.
____________Applications Information
Fixed +3.3V Step-Down
Converter Application
Figure 3 shows the standard 3.3V step-down circuit with
components shown for commercial temperature range
applications. Figures 4, 5, and Table 2 suggest external
component values for both SO and through-hole wide
temperature range applications. These circuits are use-
ful in systems that require high current and high efficien-
cy and are powered by an unregulated supply, such as
a battery or wall-plug AC-DC adapter.
The MAX748A delivers a guaranteed 300mA for input
voltages of 4V to 16V, and a guaranteed 500mA for
Output Filter Capacitor Selection
The primary criterion for selecting the output filter
capacitor is low effective series resistance (ESR). The
product of the inductor-current variation and the output
capacitor’s ESR determines the amplitude of the saw-
tooth ripple seen on the output voltage. Minimize the
output filter capacitor’s ESR to maintain AC stability.
9
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