Rainbow Electronics MAX653 - Manual

________________________________________________________________ Maxim Integrated Products 1
_______________General Description
The MAX639/MAX640/MAX653 step-down switching
regulators provide high efficiency over a wide range of
load currents, delivering up to 225mA. A current-limiting
pulse-frequency-modulated (PFM) control scheme gives
the devices the benefits of pulse-width-modulated
(PWM) converters (high efficiency at heavy loads), while
using only 10µA of supply current (vs. 2mA to 10mA for
PWM converters). The result is high efficiency over a
wide range of loads.
The MAX639/MAX640/MAX653 input range is 4V to
11.5V, and the devices provide lower preset output volt-
ages of 5V, 3.3V, and 3V, respectively. Or, the output
can be user-adjusted to any voltage from 1.3V to the
input voltage.
The MAX639/MAX640/MAX653 have an internal 1A power
MOSFET switch, making them ideal for minimum-compo-
nent, low- and medium-power applications. For increased
output drive capability, use the MAX649/MAX651/MAX652
step-down controllers, which drive an external P-channel
FET to deliver up to 5W.
________________________Applications
9V Battery to 5V, 3.3V, or 3V Conversion
High-Efficiency Linear Regulator Replacement
Portable Instruments and Handy-Terminals
5V-to-3.3V Converters
____________________________Features
♦ High Efficiency for a Wide Range of Load Currents
♦ 10µA Quiescent Current
♦ Output Currents Up to 225mA
♦ Preset or Adjustable Output Voltage:
5.0V (MAX639)
3.3V (MAX640)
3.0V (MAX653)
♦ Low-Battery Detection Comparator
♦ Current-Limiting PFM Control Scheme
______________Ordering Information
Ordering Information continued on last page.
* Contact factory for dice specifications.
MAX639/MAX640/MAX653
5V/3.3V/3V/Adjustable, High-Efficiency,
Low I
Q
, Step-Down DC-DC Converters
19-4505; Rev 3; 8/97
PART TEMP. RANGE PIN-PACKAGE
MAX639 CPA 0°C to +70°C 8 Plastic DIP
MAX639CSA 0°C to +70°C 8 SO
MAX639C/D 0°C to +70°C Dice*
1
2
3
4 5
8
7
6
MAX639
MAX640
MAX653
DIP/SO
TOP VIEW
VFB
SHDN
V+
LX
VOUT
LBO
LBI
GND
__________________Pin Configuration
GND
MAX639
SHDN
LX
VOUT
LBO
LOW-BATTERY
DETECTOR
OUTPUT
ON/OFF
LBI
LOW-BATTERY
DETECTOR
INPUT
OUTPUT
5V
225mA
INPUT
5.5V TO 11.5V
V+
VFB
__________Typical Operating Circuit
MAX639ESA -40°C to +85°C 8 SO
MAX639EPA -40°C to +85°C 8 Plastic DIP
MAX639MJA -55°C to +125°C 8 CERDIP
EVALUATION KIT
INFORMATION INCLUDED
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.