19-1357; Rev 1; 7/98
KIT
ATION
EVALU
BLE
AVAILA
High-Efficiency, PWM, Step-Down
DC-DC Controllers in 16-Pin QSOP
General Description
____________________________Features
o
96% Efficiency
o
Small, 16-Pin QSOP Package
(half the size of a 16-pin narrow SO)
o
Pin-Compatible with MAX797 (MAX1653/MAX1655)
o
Output Voltage Down to 1V (MAX1655)
o
4.5V to 30V Input Range
o
99% Duty Cycle for Lower Dropout
o
170µA Quiescent Supply Current
o
3µA Logic-Controlled Shutdown
o
Dual, N-Channel, Synchronous-Rectified Control
o
Fixed 150kHz/300kHz PWM Switching,
or Synchronized from 190kHz to 340kHz
o
Programmable Soft Start
o
Low-Cost Secondary Outputs (MAX1652/MAX1654)
MAX1652–MAX1655
The MAX1652–MAX1655 are high-efficiency, pulse-
width-modulated (PWM), step-down DC-DC controllers
in small QSOP packages. The MAX1653/MAX1655 also
come in 16-pin narrow SO packages that are pin-
compatible upgrades to the popular MAX797. Improve-
ments include higher duty-cycle operation for better
dropout, lower quiescent supply currents for better
light-load efficiency, and an output voltage down to 1V
(MAX1655).
The MAX1652–MAX1655 achieve up to 96% efficiency
and deliver up to 10A using a unique Idle Mode™ syn-
chronous-rectified PWM control scheme. These devices
automatically switch between PWM operation at heavy
loads and pulse-frequency-modulated (PFM) operation
at light loads to optimize efficiency over the entire out-
put current range. The MAX1653/MAX1655 also feature
logic-controlled, forced PWM operation for noise-sensi-
tive applications.
All devices operate with a selectable 150kHz/300kHz
switching frequency, which can also be synchronized
to an external clock signal. Both external power switch-
es are inexpensive N-channel MOSFETs, which provide
low resistance while saving space and reducing cost.
The MAX1652 and MAX1654 have an additional feed-
back pin that permits regulation of a low-cost second
output tapped from a transformer winding. The
MAX1652 provides an additional positive output. The
MAX1654 provides an additional negative output.
The MAX1652–MAX1655 have a 4.5V to 30V input volt-
age range. The MAX1652/MAX1653/MAX1654’s output
range is 2.5V to 5.5V while the MAX1655’s output range
extends down to 1V. An evaluation kit (MAX1653EVKIT)
is available to speed designs.
Ordering Information
PART
MAX1652EEE
MAX1653ESE
MAX1653EEE
MAX1654EEE
MAX1655ESE
MAX1655EEE
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 Narrow SO
16 QSOP
16 QSOP
16 Narrow SO
16 QSOP
Applications
Notebook Computers
PDAs
Cellular Phones
Hand-Held Computers
Handy-Terminals
Mobile Communicators
Distributed Power
MAX1654
2.5
MAX1653
2.5
MAX1652
2.5
PART
FEEDBACK
VOLTAGE (V)
Selection Guide
SPECIAL
FEATURE
COMPATIBILITY
Regulates positive Same pin order
secondary voltage as MAX796, but
(such as +12V)
smaller package
Logic-controlled, Pin-compatible
low-noise mode with MAX797
Regulates negative Same pin order
secondary voltage as MAX799, but
(such as -5V)
smaller package
Low output volt-
ages (1V to 5.5V);
logic-controlled,
low-noise mode
Pin compatible
with MAX797
(except for feed-
back voltage)
Pin Configurations appear at end of data sheet.
Idle Mode is a trademark of Maxim Integrated Products.
MAX1655
1
________________________________________________________________
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.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
