19-0211; Rev 4; 5/96
NUAL
KIT MA
UATION TA SHEET
EVAL
WS DA
FOLLO
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
____________________________Features
o
o
o
o
o
o
o
o
o
o
0.8V to 6.0V Input Supply Voltage
0.8V Typ Start-Up Supply Voltage
85% Efficiency at 100mA
25µA Quiescent Current
1µA Shutdown Mode
125mA and 500mA Switch-Current Limits Permit
Use of Low-Cost Inductors
Up to 500kHz Switching Frequency
±1.5% Reference Tolerance Over Temperature
Low-Battery Detector (LBI/LBO)
8-Pin SO and µMAX Packages
_______________General Description
The MAX856–MAX859 are high-efficiency, CMOS, step-
up, DC-DC switching regulators for small, low input volt-
age or battery-powered systems. The MAX856/MAX858
accept a positive input voltage between 0.8V and V
OUT
and convert it to a higher, pin-selectable output voltage of
3.3V or 5V. The MAX857/MAX859 adjustable versions
accept 0.8V to 6.0V input voltages and generate higher
adjustable output voltages in the 2.7V to 6.0V range.
Typical efficiencies are greater than 85%. Typical quies-
cent supply current is 25µA (1µA in shutdown).
The MAX856–MAX859 combine ultra-low quiescent supply
current and high efficiency to give maximum battery life. An
internal MOSFET power transistor permits high switching
frequencies. This benefit, combined with internally set peak
inductor current limits, permits the use of small, low-cost
inductors. The MAX856/MAX857 have a 500mA peak
inductor current limit. The MAX858/MAX859 have a 125mA
peak inductor current limit.
MAX856–MAX859
______________Ordering Information
PART
MAX856CSA
MAX856CUA
MAX856C/D
MAX856ESA
MAX856MJA
MAX857CSA
MAX857CUA
MAX857C/D
MAX857ESA
MAX857MJA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
8 SO
8 µMAX
Dice*
8 SO
8 CERDIP
†
8 SO
8 µMAX
Dice*
8 SO
8 CERDIP
†
________________________Applications
3.3V to 5V Step-Up Conversion
Palmtop Computers
Portable Data-Collection Equipment
Personal Data Communicators/Computers
Medical Instrumentation
2-Cell & 3-Cell Battery-Operated Equipment
Glucose Meters
__________Typical Operating Circuit
INPUT
0.8V TO V
OUT
Ordering Information continued at end of data sheet.
* Dice are tested at T
A
= +25°C only.
†
Contact factory for availability.
__________________Pin Configuration
TOP VIEW
47µH
OUTPUT
5V AT 100mA
OR
3.3V AT 125mA
68µF
SHDN
3/5
1
2
8
7
LX
GND
OUT
LBI
ON/OFF
SHDN
LX
1N5817
REF
3
LBO
4
MAX856
MAX858
6
5
MAX856
3V/5V SELECT
LOW-BATTERY
DETECTOR
INPUT
3/5
LBI
REF
LBO
LOW-BATTERY
DETECTOR OUTPUT
OUT
SHDN
FB
1
2
SO/µMAX
8
7
LX
GND
OUT
LBI
GND
REF
3
LBO
4
MAX857
MAX859
6
5
SO/µMAX
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
