19-1541; Rev 2; 8/05
KIT
ATION
EVALU
E
AILABL
AV
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
Features
The MAX1715 PWM controller provides the 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.
Maxim’s proprietary Quick-PWM™ quick-response,
constant-on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides
100ns “instant-on” response to load transients while
maintaining a relatively constant switching frequency.
♦ Ultra-High Efficiency
The MAX1715 achieves high efficiency at a reduced
cost by eliminating the current-sense resistor found in
traditional current-mode PWMs. Efficiency is further
enhanced by its ability to drive very large synchronousrectifier MOSFETs.
Single-stage buck conversion allows this device to
directly step down high-voltage batteries for the highest
possible efficiency. Alternatively, two-stage conversion
(stepping down the +5V system supply instead of the
battery) at a higher switching frequency allows the minimum possible physical size.
♦ 200/300/420/540kHz Nominal Switching Frequency
The MAX1715 is intended for CPU core, chipset,
DRAM, or other low-voltage supplies as low as 1V. The
MAX1715 is available in a 28-pin QSOP package. For
applications requiring VID compliance or DAC control
of output voltage, refer to the MAX1710/MAX1711 data
sheet. For a single-output version, refer to the MAX1714
data sheet.
♦ No Current-Sense Resistor (lossless ILIMIT)
♦ Quick-PWM with 100ns Load-Step Response
♦ 1% VOUT Accuracy over Line and Load
♦ Dual-Mode Fixed 1.8V/3.3V/Adj or 2.5V/Adj Outputs
♦ Adjustable 1V to 5.5V Output Range
♦ 2V to 28V Battery Input Range
♦ Over/Undervoltage Protection
♦ 1.7ms Digital Soft-Start
♦ Drives Large Synchronous-Rectifier FETs
♦ Power-Good Indicator
Ordering Information
TEMP RANGE
PIN-PACKAGE
MAX1715EEI
PART
-40°C to +85°C
28 QSOP
MAX1715EEI+
-40°C to +85°C
28 QSOP
+ Denotes lead-free package.
Minimal Operating Circuit
Applications
Notebook Computers
CPU Core Supply
5V INPUT
BATTERY
4.5V TO 28V
VDD
Chipset/RAM Supply as Low as 1V
V+
VCC
1.8V and 2.5V I/O Supply
MAX1715
ILIM1
ILIM2
ON1
ON2
BST1
OUTPUT1
1.8V
BST2
DH1
DH2
LX1
LX2
DL1
DL2
TON
Pin Configuration appears at end of data sheet.
OUTPUT2
2.5V
PGND
OUT1
OUT2
PGOOD
SKIP
REF
FB1 AGND FB2
Quick-PWM is a trademark 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.
MAX1715
General Description
