MAX778L Datasheet PDF


Part Number

MAX778L

Description

Low-Voltage Input / 3V/3.3V/5V/ Adjustable Output / Step-Up DC-DC Converters

Manufacture

Maxim

Total Page 12 Pages
PDF Download
Download MAX778L Datasheet PDF


Features Datasheet pdf 19-0186; Rev 2; 7/96 NUAL KIT MA ATION U EET L H A S V E TA WS DA FOLLO Low-V oltage Input, 3V/3.3V/5V/ Adjustable Ou tput, Step-Up DC-DC Converters ________ ____________________Features o 1V to 4. 5V Input Guarantees Start-Up Under Load o Up to 210mA Output o Load Fully Disc onnected in Shutdown o 82% Efficiency o Output in Regulation with Input Voltag e above Output Voltage o Internal 1A Po wer Switch and Active Rectifier o Adjus table Current Limit Allows Low-Cost Ind uctors o 190µA No Load Supply Current o 20µA Shutdown Supply Current o 3V/3. 3V (MAX778L), 5V (MAX777L), and Adjusta ble (MAX779L) Output Voltage _________ ______General Description The MAX777L/M AX778L/MAX779L are pulse-skipping DC-D.
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MAX778L Datasheet
19-0186; Rev 2; 7/96
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Low-Voltage Input, 3V/3.3V/5V/
Adjustable Output, Step-Up DC-DC Converters
_______________General Description
The MAX777L/MAX778L/MAX779L are pulse-skipping DC-DC
converters that step up from low-voltage inputs (1V guaran-
teed). They require only three external components—an induc-
tor (typically 22µH) and two capacitors. The MAX777L delivers
a 5V output, the MAX778L generates pin-selectable voltages of
3.0V or 3.3V, and the MAX779L output can be adjusted from
2.5V to 6V through an external resistive divider.
The devices include an Active RectifierTM that eliminates the
need for an external catch diode, and permits regulation even
when the input is greater than the output. Also, unlike those in
other step-up converters, the MAX777L/MAX778L/MAX779L’s
Active RectifierTM turns off in the shutdown mode, disconnect-
ing the output from the source. This eliminates the current drain
associated with conventional step-up converters when off or in
shutdown.
High-frequency operation (up to 150kHz) allows the use of
small, surface-mount inductors with values of 10µH or less.
Supply current is 190µA under no load and only 20µA in stand-
by mode; supply voltage can range from 1V to 4.5V (1 to 3
cells). With a 2V input, the devices typically deliver 200mA at
5V, or 300mA at 3V.
For fully specified devices designed for step-up/step-down
applications (where the input can be above or below the out-
put), refer to the MAX877L/MAX878L/MAX879L data sheet.
________________________Applications
Single Battery-Cell (1V), Step-Up Voltage Conversion
Efficient, High-Power Step-Up Regulation from
Low Input Voltages
Pagers
Portable Instruments & Hand-Held Terminals
Notebook and Palmtop Computers
__________Typical Operating Circuit
____________________________Features
o 1V to 4.5V Input Guarantees Start-Up Under Load
o Up to 210mA Output
o Load Fully Disconnected in Shutdown
o 82% Efficiency
o Output in Regulation with Input Voltage above
Output Voltage
o Internal 1A Power Switch and Active Rectifier
o Adjustable Current Limit Allows Low-Cost
Inductors
o 190µA No Load Supply Current
o 20µA Shutdown Supply Current
o 3V/3.3V (MAX778L), 5V (MAX777L), and
Adjustable (MAX779L) Output Voltage
______________Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX777LCPA
0°C to +70°C
8 Plastic DIP
MAX777LCSA
0°C to +70°C
8 SO
MAX777LC/D
0°C to +70°C
Dice*
MAX777LEPA
-40°C to +85°C
8 Plastic DIP
MAX777LESA
-40°C to +85°C
8 SO
MAX777LMJA -55°C to +125°C
8 CERDIP**
Ordering Information continued at end of data sheet.
* Dice are specified at TA = +25°C, DC parameters only.
**Contact factory for availability and processing to MIL-STD-883.
__________________Pin Configuration
INPUT
1V TO 4.5V
TOP VIEW
22µF
ON/OFF
2
IN
1 ILIM MAX777L
5
LX
7
SHDN
6
OUT
PGND
4
AGND
3
22µH
OUTPUT
5V
100µF
ILIM 1
IN 2
AGND 3
PGND 4
MAX777L
MAX778L
MAX779L
8 N.C. (MAX777L)*
7 SHDN
6 OUT
5 LX
DIP/SO
* SEL FOR MAX778L, FB FOR MAX779L.
Active Rectifier is a trademark of Maxim Integrated Products.
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800




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