MAX1878 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – Dual-Output Step-Down and LCD Step-Up Power Supply for PDAs

19-2248; Rev 1; 12/03
EVAALVUAAILTAIOBNLEKIT
Dual-Output Step-Down and LCD Step-Up
Power Supply for PDAs
General Description
The MAX1878 dual power supply contains a step-down
and step-up DC-DC converter in a small 12-pin QFN
package for use in PDAs. The step-down DC-DC convert-
er delivers over 500mA to an output as low as 1.25V for
logic power. The step-up DC-DC converter delivers over
15mA and an output as high as 28V for a liquid crystal dis-
play (LCD). With an input voltage from 2.0V to 5.5V the
MAX1878 is intended for use in systems powered by a
2-cell alkaline or 1-cell lithium-ion (Li+) battery.
Fast switching frequency allows the use of small inductors
and capacitors, and the low 19µA typical quiescent cur-
rent allows high efficiency when the system is in standby
mode. Each output can be independently enabled.
The MAX1878 is available in a small 1mm high 4mm x
4mm 12-pin QFN package and requires no external FETs.
The MAX1878 evaluation kit is available to speed designs.
Features
♦ Evaluation Kit Available to Speed Designs
♦ Two Output Voltages
Main Output: 1.25V to V_IN
LCD Output: Up to 28V
♦ 2.0V to 5.5V Input Range
♦ Low 19µA Quiescent Supply Current
♦ 1µA Shutdown Supply Current
♦ High Switching Frequency for Small External
Components
♦ Small 1mm High 4mm x 4mm 12-Pin QFN Package
________________________Applications
Personal Digital Assistants (PDA)
Organizers/Translators
MP3 Players
GPS Receivers
__________Typical Operating Circuit
INPUT
2.0V TO 5.5V
MAIN
LCD
ON
OFF
ON
OFF
10µH
IN
LXLCD
FBLCD
AIN1
AIN2
MAX1878 LX
FB
ON
ONLCD
10µH
LCD OUTPUT
UP TO 28V
0.1µF
MAIN OUTPUT
1.25V TO VIN
PGND AGND PGNDLCD
Ordering Information
PART
MAX1878EGC
TEMP RANGE
-40°C to +85°C
PIN-
PACKAGE
12-QFN
TOP
MARK
AAAO
Pin Configuration
TOP VIEW
IN 1
LX 2
AIN1 3
12 11 10
9 LXLCD
MAX1878EGC
8 AGND
7 ON
4
5
6
4mm x 4mm QFN
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.