MAX1802 Datasheet, PDF (1/28 Pages) Maxim Integrated Products – Digital Camera Step-Down Power Supply

19-1850; Rev 0; 10/00
Digital Camera Step-Down
Power Supply
General Description
The MAX1802 provides a complete power-supply solu-
tion for digital still cameras and video cameras by inte-
grating two high-efficiency step-down DC-DC converters
and three auxiliary step-up controllers. This complete
solution is targeted for applications that use either three
to four alkaline cells or two lithium-ion (Li+) cells.
The main step-down DC-DC controller accepts inputs
from 2.5V to 11V and regulates a resistor-adjustable out-
put from 2.7V to 5.5V. It uses a synchronous rectifier to
regulate the output with up to 94% efficiency. An
adjustable operating frequency (up to 1MHz) facilitates
designs for optimum size, cost, and efficiency.
The core step-down DC-DC converter accepts inputs
from 2.7V to 5.5V and regulates a resistor-adjustable
output from 1.25V to 5.5V. It delivers 500mA with up to
94% efficiency.
The three auxiliary step-up controllers can be used to
power the digital camera’s CCD, LCD, and backlight.
The MAX1802 also features expandability by supplying
power, an oscillator signal, and a reference to the
MAX1801, a low-cost slave DC-DC controller that sup-
ports step-up, single-ended primary inductance con-
verter (SEPIC), and fly-back configurations.
The MAX1802 is available in a space-saving 32-pin
TQFP package (5mm x 5mm body), and the MAX1801
is available in an 8-pin SOT-23 package. An evaluation
kit (MAX1802EVKIT) featuring both devices is available
to expedite designs.
________________________Applications
Digital Still Cameras
Digital Video Cameras
Hand-Held Devices
Internet Access Tablets
PDAs
DVD Players
Pin Configuration appears at end of data sheet.
Features
o 2.5V to 11V Input Voltage Range
o Main DC-DC Controller
94% Efficiency
+2.7V to +5.5V Adjustable Output Voltage
Up to 100% Duty Cycle
Independent Shutdown
o Core DC-DC Converter
94% Efficiency
Up to 500mA Load Efficiency
Output Voltage Adjustable Down to 1.25V
Independent Shutdown
o Three Auxiliary DC-DC Controllers
Adjustable Maximum Duty Cycle
Independent Shutdown
o Power, Oscillator, and Reference Outputs to Drive
External Slave Controllers (MAX1801)
o Up to 1MHz Switching Frequency
o 3µA Supply Current in Shutdown Mode
o Internal Soft-Start
o Overload Protection for All DC-DC Converters
o Compact 32-Pin TQFP Package
Ordering Information
PART
TEMP. RANGE PIN-PACKAGE
MAX1802EHJ
-40°C to +85°C 32 TQFP
Note: Refer to the separate data sheet for MAX1801EKA in an 8-
pin SOT.
Typical Operating Circuit
INPUT
2.5V TO 11V
MAX1802
MASTER
MAIN
CORE
CCD
CCFL
TFT
OSC
POWER REF
MAX1801
SLAVE
MOTOR
________________________________________________________________ Maxim Integrated Products 1
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