_______________General Description
The MAX863 dual-output DC-DC converter contains
two independent, high-efficiency, current-limited PFM
(pulse-frequency-modulated) boost controllers integrat-
ed on one space-saving circuit. It accepts inputs down
to 1.5V and is intended for use in small, hand-held
equipment powered from two or three battery cells or
one lithium ion cell. The MAX863 comes in a miniature
16-pin QSOP that fits in the same area as a standard 8-
pin SO.
Each output can be set to any boosted voltage using
two external resistors. One of the outputs also uses the
Dual-Mode™ feature, which allows a 3.3V or 5V output.
Both controllers drive inexpensive, external N-channel
MOSFETs at up to 300kHz, permitting small external
components.
The MAX863 extends battery life with 82% efficiency
over a 20mA to 1A output range. It also saves battery
life with a low 65µA (max) quiescent supply current,
even when both supplies are on. A separate logic-con-
trolled shutdown for each converter allows power-man-
agement flexibility and decreases supply current to just
1µA (max).
Other features include soft-start to prevent surge cur-
rents when powering up, and a built-in LBI/LBO low-
battery detector. The MAX863 evaluation kit (MAX863
EVKIT-SO) is available to assist with designs. For a sin-
gle-output controller, refer to the MAX1771 data sheet.
________________________Applications
2 or 3 Cell Portable Equipment
Organizers, PDAs, and Palmtops
Dual 3.3V/5V Logic and Positive LCD Supply
Flash Memory Programmers
Split 3.3V Logic and 5V Memory Systems
____________________________Features
♦
Smallest Dual Boost Controller
♦
16-Pin QSOP Fits in 8-Pin SO Area
♦
High Efficiency (>80% from 20mA to 1A)
♦
65µA (max) Quiescent Supply Current
♦
1µA (max) Shutdown Current
♦
LBI/LBO Low-Battery Detector
♦
Drives Surface-Mount, Dual N-Channel FET
♦
2 or 3 NiCd/NiMH Cell or 1 Lithium Cell Operation
♦
Also Configurable as Step-Up/Down Controller
MAX863
Dual, PFM, Step-Up
DC-DC Controller
________________________________________________________________
Maxim Integrated Products
1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
SHDN1
SHDN2
LBI
LBO
BOOT
FB1
V
DD
OUT1
TOP VIEW
MAX863
FB2
SEL
CS2
EXT2
PGND
GND
EXT1
CS1
QSOP
__________________Pin Configuration
Call toll free 1-800-998-8800 for free samples or literature.
PART
MAX863C/D
MAX863IKE
MAX863EKE
-40°C to +85°C
-25°C to +85°C
0°C to +70°C
TEMP. RANGE
PIN-PACKAGE
Dice*
16 QSOP
16 QSOP
ADVANCE INFORMATION
All information in this data sheet is preliminary
and subject to change.
6/95
EVALUATION KIT WILL BE AVAILABLE
______________Ordering Information
*Dice are tested at T
A
= +25°C.
Dual Mode is a trademark of Maxim Integrated Products.
MAX863
Dual, PFM, Step-Up
DC-DC Controller
2
_______________________________________________________________________________________
MAX863
ON /OFF
3.3V/5V SELECT
LOW-BATTERY DETECTOR INPUT
LBO
FB2
CS2
EXT2
OUTPUT 1
3.3V or 5V up to 1A
INPUT
2.7V to V
OUT
PGND
GND
FB1
V
DD
BOOT
OUTPUT 2
(ADJUSTABLE)
LOW-BATTERY DETECTOR OUTPUT
SHDN2
SHDN1
SEL
LBI
OUT1
CS1
EXT1
N
N
___________________________________________________Typical Operating Circuit