19-1923; Rev 0; 1/01
High-Efficiency, 10-Pin µMAX, Step-Down
Controllers for Notebooks
General Description
The MAX1762/MAX1791 PWM step-down controllers
provide high efficiency, excellent transient response,
and high DC output accuracy needed for stepping
down high-voltage batteries to generate low-voltage
CPU core, I/O, and chipset RAM supplies in notebook
computers and PDAs.
Maxim’s proprietary Quick-PWM™ pulse-width modula-
tor is a free-running constant on-time type with input
feed-forward. Its high operating frequency (300kHz)
allows small external components to be utilized in PC
board area-critical applications such as subnotebook
computers and smart phones. PWM operation occurs
at heavy loads, and automatic switchover to pulse-skip-
ping operation occurs at lighter loads. The external
high-side P-channel and low-side N-channel MOSFETs
require no bootstrap components. The MAX1762/
MAX1791 are simple, easy to compensate, and do not
have the noise sensitivity of conventional fixed-frequen-
cy current-mode PWMs.
These devices achieve high efficiency at a reduced
cost by eliminating the current-sense resistor found in
traditional current-mode PWMs. Efficiency is further
enhanced by their ability to drive synchronous-rectifier
MOSFETs. The MAX1762/MAX1791 come in a 10-pin
µMAX package and offer two fixed voltages (Dual
Mode™) for each device, 1.8V/2.5V/adj (MAX1762) and
3.3V/5.0V/adj (MAX1791).
o
High Operating Frequency (300kHz)
o
No Current-Sense Resistor
o
Accurate Current Limit
o
±1% Total DC Error over Line and During
Continuous Conduction
o
Dual Mode Fixed Output
1.8V/2.5V/adj (MAX1762)
3.3V/5.0V/adj (MAX1791)
o
0.5V to 5.5V Output Adjust Range
o
5V to 20V Input Range
o
Automatic Light-Load Pulse Skipping Operation
o
Free-Running On-Demand PWM
o
Foldback Mode™ UVLO
o
PFET/NFET Synchronous Buck
o
4.65V at 25mA Linear Regulator Output
o
5µA Shutdown Supply Current
o
230µA Quiescent Supply Current
o
10-Pin µMAX Package
Features
MAX1762/MAX1791
Ordering Information
PART
MAX1762EUB
MAX1791EUB
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
10 µMAX
10 µMAX
________________________Applications
Notebooks
Subnotebooks
Digital Cameras
1.8V/2.5V Logic
and I/O Supplies
Handy-Terminals
PDAs
Smart Phones
Pin Configuration
TOP VIEW
Typical Operating Circuit
V
BATT
(5V TO 20V)
VL
1
REF
VL
MAX1762
MAX1791
REF
FB
OUT
SHDN
DH
CS
DL
GND
V
OUT
1.8V/3.3V
VP
10
VP
9
DH
CS
DL
GND
2
3
4
5
FB
OUT
SHDN
MAX1762
MAX1791
8
7
6
µMAX
Quick-PWM, Dual Mode, and Foldback Mode are a trade-
marks of Maxim Integrated Products.
________________________________________________________________
Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
