MAX1775 Datasheet, PDF (1/15 Pages) Maxim Integrated Products – Dual-Output Step-Down DC-DC Converter for PDA/Palmtop Computers

19-1811; Rev 1; 8/01
EVAALVUAAILTAIOBNLEKIT
Dual-Output Step-Down
DC-DC Converter for PDA/Palmtop Computers
General Description
The MAX1775 is a dual, step-down DC-DC converter
that generates both the main (+3.3V at over 2A) and
core (+1.8V at up to 1.5A) supplies for a complete
power solution for PDAs, subnotebooks, and other
hand-held devices. The main output is adjustable from
+1.25V to +5.5V. The core output is adjustable from 1V
to 5V. Both switching converters operate at up to
1.25MHz for small external components and use syn-
chronous rectifiers to achieve efficiencies up to 95%.
Operation with up to 100% duty cycle provides the low-
est possible dropout voltage to extend useful battery
life.
The MAX1775 accepts inputs from +2.7V up to +28V,
allowing use with many popular battery configurations as
well as AC-DC wall adapters. Digital soft-start reduces
battery current surges at power-up. Both the main and
core converters have separate shutdown inputs. The
MAX1775 comes in a small 16-pin QSOP package.
The MAX1775 evaluation kit is available to help reduce
design time.
________________________Applications
Hand-Held Computers
PDAs
Internet Access Tablets
POS Terminals
Subnotebooks
Features
o Dual, High-Efficiency, Synchronous Rectified
Step-Down Converter
o Main Power
Adjustable from +1.25V to +5.5V
Over 2A Load Current
Up to 95% Efficiency
o Core Power
Adjustable from 1V to 5V
Internal Switches
Up to 1.5A Load Current
Up to 92% Efficiency
o 100% (max) Duty Cycle
o Up to 1.25MHz Switching Frequency
o Input Voltage Range from +2.7V to +28V
o 170µA Quiescent Current
o 5µA Shutdown Current
o Digital Soft-Start
o Independent Shutdown Inputs
PART
MAX1775EEE
Ordering Information
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
16 QSOP
Typical Operating Circuit
IN 2.7V TO 5.5V (28V IN CASCADE)
Pin Configuration
TOP VIEW
SHDNM 1
SHDNC 2
PGND 3
NDRV 4
CVL 5
IN 6
PDRV 7
CVH 8
MAX1775
16 LXC
15 INC
14 GND
13 FBC
12 CS-
11 CS+
10 FBM
9 REF
16 QSOP
IN CVH
ON
INC
OFF SHDNM
ON
OFF SHDNC
PDRV
NDRV
CVL
MAX1775 _CS+
REF
CS-
FBM
PGND
LXC
GND
FBC
MAIN
3.3V
OVER 2A
CORE
1.8V
1.5A
________________________________________________________________ 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.