19-4505; Rev 3; 8/97
5 V/3 .3 V/3 V/Ad ju s t a b le , Hig h -Effic ie n c y,
Lo w IQ, S t e p -Do w n DC-DC Co n ve rt e rs
940/MAX653
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
♦ High Efficiency for a Wide Range of Load Currents
♦ 10µA Quiescent Current
The MAX639/MAX640/MAX653 ste p-down switc hing
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 d e vic e s the b e ne fits of p uls e -wid th-mod ula te d
(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.
♦ Output Currents Up to 225mA
♦ Preset or Adjustable Output Voltage:
5.0V (MAX639)
3.3V (MAX640)
3.0V (MAX653)
The MAX639/MAX640/MAX653 inp ut ra ng e 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.
♦ Low-Battery Detection Comparator
♦ Current-Limiting PFM Control Scheme
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.
______________Ord e rin g In fo rm a t io n
PART
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
8 Plastic DIP
8 SO
MAX639CPA
MAX639CSA
MAX639C/D
MAX639EPA
MAX639ESA
MAX639MJA
0°C to +70°C
0°C to +70°C
Dice*
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
8 Plastic DIP
8 SO
________________________Ap p lic a t io n s
9V Battery to 5V, 3.3V, or 3V Conversion
High-Efficiency Linear Regulator Replacement
Portable Instruments and Handy-Terminals
5V-to-3.3V Converters
8 CERDIP
Ordering Information continued on last page.
* Contact factory for dice specifications.
__________Typ ic a l Op e ra t in g Circ u it
__________________P in Co n fig u ra t io n
TOP VIEW
INPUT
5.5V TO 11.5V
OUTPUT
5V
V+
225mA
LX
VOUT
LBO
8
7
6
5
1
2
3
4
SHDN
VFB
MAX639
MAX640
MAX653
MAX639
SHDN
LBI
ON/OFF
VOUT
LBO
LBI
V+
LX
LOW-BATTERY
DETECTOR
OUTPUT
LOW-BATTERY
DETECTOR
INPUT
GND
DIP/SO
VFB
GND
________________________________________________________________ Maxim Integrated Products
1
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.