5 V/1 2 V/1 5 V o r Ad ju s t a b le , High-Effic ie nc y,
Low I , Ste p-Up DC-DC Controlle rs
Q
0–MAX73
lead, and the output filter capacitor ground lead to a
single point (star ground configuration). Also, minimize
lead lengths to reduce stray capacitance, trace resis-
tance, and radiated noise. Place input bypass capaci-
tor C2 as close as possible to V+ and GND.
S t a rt in g Up u n d e r Lo a d
The Typical Operating Characteristics show the Start-
Up Voltage vs. Load Current graph for bootstrapped-
mod e op e ra tion. This g ra p h d e p e nd s on the typ e
of p owe r s witc h us e d . The MAX770–MAX773 a re
not d e s ig ne d to s ta rt up und e r full loa d in b oot-
strapped mode with low input voltages.
Excessive noise at the V+ input may falsely trigger the
timing circuitry, resulting in short pulses at EXT. If this
occurs it will have a negligible effect on circuit efficien-
cy. If desired, place a 4.7µF directly across the V+ and
GND pins (in parallel with the 0.1µF C2 bypass capaci-
tor) to reduce the noise at V+.
La yo u t Co n s id e ra t io n s
Due to high current levels and fast switching wave-
forms, which radiate noise, proper PC board layout is
essential. Protect sensitive analog grounds by using a
star ground configuration. Minimize ground noise by
connecting GND, the input bypass capacitor ground
Table 2. Component Suppliers
PRODUCTION
INDUCTORS
CAPACITORS
TRANSISTORS
N-FET
DIODES
Sumida
CD54 series
CDR125 series
Coiltronics
Siliconix
Si9410DY
Si9420DY (high voltage)
Motorola
MTP3055EL
MTD20N03HDL
Matsuo
267 series
Sprague
Nihon
EC10 series
Surface Mount
595D series
CTX20 series
Sanyo
OS-CON series
Nichicon
PL series
United Chemi-Con
LXF series
Sumida
RCH855 series
RCH110 series
Renco
NPN
Zetex
ZTX694B
Motorola
1N5817–1N5822
MUR115 (high voltage)
Through Hole
RL1284-18
SUPPLIER
PHONE
FAX
Coiltronics
Matsuo
USA: (561) 241-7876
(561) 241-9339
USA: (714) 969-2491
Japan: 81-6-337-6450
(714) 960-6492
81-6-337-6456
Nichicon
Nihon
USA: (847) 843-7500
USA: (805) 867-2555
USA: (516) 586-5566
(847) 843-2798
(805) 867-2698
(516) 586-5562
Renco
Sanyo
USA: (619) 661-6835
Japan: 81-7-2070-6306
(619) 661-1055
81-7-2070-1174
Sumida
USA: (847) 956-0666
Japan: 81-3-3607-5111
81-3-3607-5144
(714) 255-9400
United Chemi-Con
Zetex
USA: (714) 255-9500
USA: (516) 543-7100
UK: 44-61-627-4963
(516) 864-7630
44-61-627-5467
______________________________________________________________________________________
19
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
