Rainbow Electronics MAX859 - Manual

_______________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.
________________________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
____________________________Features
♦ 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
______________Ordering Information
Ordering Information continued at end of data sheet.
* Dice are tested at T A = +25°C only.
† Contact factory for availability.
MAX856–MAX859
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
________________________________________________________________ Maxim Integrated Products 1
1
2
3
4
8
7
6
5
LX
GND
OUT
LBI LBO
REF
3/5
SHDN
MAX856
MAX858
SO/ µ MAX
TOP VIEW
1
2
3
4
8
7
6
5
LX
GND
OUT
LBI LBO
REF
FB
SHDN
MAX857
MAX859
SO/ µ MAX
__________________Pin Configuration
MAX856
SHDN
3/5
REF
LX
GND
OUT
INPUT
0.8V TO V OUT
1N5817
OUTPUT
5V AT 100mA
OR
3.3V AT 125mA
LBO
68 µ F
47 µ H
LOW-BATTERY
DETECTOR OUTPUT
ON/OFF
3V/5V SELECT
LBI
LOW-BATTERY
DETECTOR
INPUT
__________Typical Operating Circuit
19-0211; Rev 4; 5/96
PART TEMP. RANGE PIN-PACKAGE
MAX856 CSA 0°C to +70°C 8 SO
MAX856CUA 0°C to +70°C 8 µMAX
MAX856C/D 0°C to +70°C Dice*
MAX856ESA -40°C to +85°C 8 SO
MAX856MJA -55°C to +125°C 8 CERDIP †
MAX857 CSA 0°C to +70°C 8 SO
MAX857CUA 0°C to +70°C 8 µMAX
MAX857C/D 0°C to +70°C Dice*
MAX857ESA -40°C to +85°C 8 SO
MAX857MJA -55°C to +125°C 8 CERDIP †
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800