19-1923; Rev 0; 1/01
High-Efficiency, 10-Pin µMAX, Step-Down
Controllers for Notebooks
General Description
Features
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.
o High Operating Frequency (300kHz)
o No Current-Sense Resistor
o Accurate Current Limit
o ±±1 ꢀotaꢁ ꢂC ꢃrror oꢄer Line anꢅ ꢂuring
Continuous Conꢅuction
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.
o ꢂuaꢁ Moꢅe Fixeꢅ Output
±.8V/2.5V/aꢅj (MAX±762)
3.3V/5.0V/aꢅj (MAX±79±)
o 0.5V to 5.5V Output Aꢅjust Range
o 5V to 20V Input Range
o Automatic Light-Loaꢅ Puꢁse Skipping Operation
o Free-Running On-ꢂemanꢅ PWM
o Foꢁꢅback Moꢅe™ UVLO
o PFꢃꢀ/NFꢃꢀ Synchronous Buck
o 4.65V at 25mA Linear Reguꢁator Output
o 5µA Shutꢅown Suppꢁy Current
o 230µA Quiescent Suppꢁy Current
o ±0-Pin µMAX Package
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).
Ordering Information
________________________Applications
PART
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
10 µMAX
Notebooks
Handy-Terminals
MAX1762EUB
MAX1791EUB
Subnotebooks
Digital Cameras
PDAs
10 µMAX
Smart Phones
1.8V/2.5V Logic
and I/O Supplies
Pin Configuration
TOP VIEW
Typical Operating Circuit
V
BATT
(5V TO 20V)
VL
REF
FB
1
2
3
4
5
10 VP
9
8
7
6
DH
CS
VL
VP
MAX1762
MAX1791
MAX1762
MAX1791
OUT
DL
SHDN
GND
DH
CS
REF
FB
V
OUT
1.8V/3.3V
µMAX
OUT
DL
Quick-PWM, Dual Mode, and Foldback Mode are a trade-
marks of Maxim Integrated Products.
SHDN
GND
________________________________________________________________ Maxim Integrated Products
±
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.