19-1219; Rev 1; 6/97
N KIT M
28V, Low-Power, High-Voltage,
Boost or Inverting DC-DC Converter
Internal, 500mA, 28V N-Channel Switch
(No External FET Required)
Generates Positive or Negative Output Voltages
80µA Supply Current
1µA Max Shutdown Current
Up to 300kHz Switching Frequency
Adjustable Current Limit Allows Use of Small,
8-Pin SO Package
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
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.
0°C to +70°C
-40°C to +85°C
Positive or Negative LCD Bias Generators
High-Efficiency DC-DC Boost Converters
Varactor Tuning Diode Bias
2-Cell and 3-Cell Battery-Powered Applications
are tested at T
= +25°C, DC parameters only.
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
POSITIVE OUTPUT VOLTAGE
NEGATIVE OUTPUT VOLTAGE
Maxim Integrated Products
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800