Rainbow Electronics MAX1802 - Manual

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
Features
♦ 2.5V to 11V Input Voltage Range
♦ Main DC-DC Controller
94% Efficiency
+2.7V to +5.5V Adjustable Output Voltage
Up to 100% Duty Cycle
Independent Shutdown
♦ Core DC-DC Converter
94% Efficiency
Up to 500mA Load Efficiency
Output Voltage Adjustable Down to 1.25V
Independent Shutdown
♦ Three Auxiliary DC-DC Controllers
Adjustable Maximum Duty Cycle
Independent Shutdown
♦ Power, Oscillator, and Reference Outputs to Drive
External Slave Controllers (MAX1801)
♦ Up to 1MHz Switching Frequency
♦ 3µA Supply Current in Shutdown Mode
♦ Internal Soft-Start
♦ Overload Protection for All DC-DC Converters
♦ Compact 32-Pin TQFP Package
MAX1802
Digital Camera Step-Down
Power Supply
________________________________________________________________ Maxim Integrated Products 1
Typical Operating Circuit
19-1850; Rev 0; 10/00
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Ordering Information
Note: Refer to the separate data sheet for MAX1801EKA in an 8-
pin SOT.
Pin Configuration appears at end of data sheet.
32 TQFP
PIN-PACKAGE TEMP. RANGE
-40°C to +85°C MAX1802EHJ
PART
MAX1802
MASTER
MAX1801
SLAVE
INPUT
2.5V TO 11V
OSC POWER REF
MOTOR
CORE
MAIN
CCD
CCFL
TFT