MAX724 데이터 시트보기 (PDF) - Maxim Integrated
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MAX724 Datasheet PDF : 13 Pages
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5A/2A Step-Down, PWM,
Switch-Mode DC-DC Regulators
In DCM, ringing occurs at VSW in the latter part of the
switch off-cycle. This is due to the inductor resonating
with the parallel capacitance of the catch diode and the
VSW node. This ringing is harmless and does not
appear at the output. Furthermore, attempts to damp
this ringing by adding circuitry will reduce efficiency
and are not advised. No off-state ringing occurs in
CCM because the diode always conducts during the
switch-off time and consequently damps any reso-
nance at VSW.
VIN
2.21V
REF
INTERNAL
100kHz CURRENT-LIMIT
BIAS OSCILLATOR COMPARATOR
ERROR
AMPLIFIER
PWM
LOGIC
FB
CONTROL
VC
SWITCH
MAX724
GND
VSW
Figure 1. MAX724 Block Diagram
INPUT
8V TO 40V
220µF
R3
2.7k
C2
0.01µF
VIN
VSW
MAX724
MAX726
VC
FB
GND
L
50µH (MAX724)
100µH (MAX726)
OUTPUT
5V at 5A (MAX724)
5V at 2A (MAX726)
D
MBR745
R1
2.8k
C1
470µF
R2
2.2k
Figure 2. Basic Step-Down Converter
_______________Component Selection
Table 1 lists component suppliers for inductors, capaci-
tors, and diodes appropriate for use with the
MAX724/MAX726. Be sure to observe specified ratings
for all components.
Table 1. Component Suppliers
Surface-Mount Components (for designs typically below 2A)
Inductors:
Sumida Electric - CDR125 Series
USA: Phone (708) 956-0666
Japan: Phone 81-3607-5111
FAX 81-3607-5144
Coiltronics - CTX series
USA: Phone (305) 781-8900
FAX (305) 782-4163
Capacitors:
Matsuo - 267 series
USA: Phone (714) 969-2491
FAX (714) 960-6492
Japan: Phone 81-6337-6450
Sprague - 595D series
USA: Phone (603) 224-1961
FAX (603) 224-1430
Diodes:
Motorola - MBRS series
USA: Phone (602) 244-5303
FAX (602) 244-4015
Nihon - NSQ series
USA: Phone (805) 867-2555
FAX (805) 867-2556
Japan: Phone 81-3-3494-7411
FAX 81-3-3494-7414
Through-Hole Components
Inductors:
Sumida - RCH-110 series
(see above for phone number)
Cadell-Burns - 7070, 7300, 6860, and 7200 series
USA: Phone (516) 746-2310
FAX (516) 742-2416
Renco - various series
USA: Phone (516) 586-5566
FAX (516) 586-5562
Coiltronics - various series
(see above for phone number)
Capacitors:
Nichicon - PL series low-ESR electrolytics
USA: Phone (708) 843-7500
FAX (708) 843-2798
Japan: Phone 81-7-5231-8461
FAX 81-7-5256-4158
United Chemi-Con - LXF series
USA: Phone (714) 255-9500
FAX (714) 255-9400
Sanyo - OS-CON low-ESR organic semiconductor
USA: Phone (619) 661-6835
FAX (619) 661-1055
Japan: Phone 81-7-2070-6306
FAX 81-7-2070-1174
Diodes:
General Purpose - 1N5820-1N5825
Motorola - MBR and MBRD series
(see above for phone number)
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