MAX629 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter

19-1219; Rev 1; 6/97
EVALUAATVIOANILKAIBTLMEANUAL
28V, Low-Power, High-Voltage,
Boost or Inverting DC-DC Converter
_______________General Description
The MAX629 low-power DC-DC converter features an
internal N-channel MOSFET switch and programmable
current limiting. It is designed to supply positive or neg-
ative bias voltages up to ±28V from input voltages in
the 0.8V to V_OUT range, and can be configured for
boost, flyback, and SEPIC topologies.
The MAX629’s current-limited pulse-frequency-modula-
tion (PFM) control scheme provides high efficiency over
a wide range of load conditions. An internal, 0.5A N-
channel MOSFET switch reduces the total part count,
and a high switching frequency (up to 300kHz) allows
for tiny surface-mount magnetics.
The MAX629’s combination of low supply current, logic-
controlled shutdown, small package, and tiny external
components makes it an extremely compact and effi-
cient high-voltage biasing solution that’s ideal for bat-
tery-powered applications. The MAX629 is available in
an 8-pin SO package.
________________________Applications
Positive or Negative LCD Bias Generators
High-Efficiency DC-DC Boost Converters
Varactor Tuning Diode Bias
Palmtop Computers
2-Cell and 3-Cell Battery-Powered Applications
____________________________Features
o Internal, 500mA, 28V N-Channel Switch
(No External FET Required)
o Generates Positive or Negative Output Voltages
o 80µA Supply Current
o 1µA Max Shutdown Current
o Up to 300kHz Switching Frequency
o Adjustable Current Limit Allows Use of Small,
Inexpensive Inductors
o 8-Pin SO Package
______________Ordering Information
PART
MAX629C/D
MAX629ESA
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
Dice*
8 SO
*Dice are tested at T_A = +25°C, DC parameters only.
Note: To order tape-and-reel shipping, add “-T” to the end of
the part number.
Pin Configuration appears at end of data sheet.
___________________________________________________Typical Operating Circuit
V_IN
+2.7V
TO +5.5V
V_CC
SHDN
LX
ISET
POL
FB
MAX629
REF
GND
V_IN
+2.7V
TO +5.5V
V_OUT
28V
V_CC
SHDN
LX
ISET
POL
MAX629 ^FB
REF
GND
-V_OUT
-28V
POSITIVE OUTPUT VOLTAGE
NEGATIVE OUTPUT VOLTAGE
________________________________________________________________ Maxim Integrated Products 1
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