19-1541; Rev 0; 1/00
KIT
ATION
EVALU
E
BL
AVAILA
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
General Description
Features
o
Ultra-High Efficiency
o
No Current-Sense Resistor (lossless I
LIMIT
)
o
Quick-PWM with 100ns Load-Step Response
o
1% V
OUT
Accuracy over Line and Load
o
Dual-Mode Fixed 1.8V/3.3V/Adj or 2.5V/Adj Outputs
o
Adjustable 1V to 5.5V Output Range
o
2V to 28V Battery Input Range
o
200/300/420/540kHz Nominal Switching Frequency
o
Over/Undervoltage Protection
o
1.7ms Digital Soft-Start
o
Drives Large Synchronous-Rectifier FETs
o
Power-Good Indicator
MAX1715
The MAX1715 PWM controller provides the high effi-
ciency, excellent transient response, and high DC out-
put 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.
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 synchronous-
rectifier 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 mini-
mum possible physical size.
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.
Ordering Information
PART
MAX1715EEI
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
28 QSOP
Applications
Notebook Computers
CPU Core Supply
Chipset/RAM Supply as Low as 1V
1.8V and 2.5V I/O Supply
5V INPUT
Minimal Operating Circuit
BATTERY
4.5V TO 28V
V
DD
V
CC
ILIM1
ILIM2
ON1
ON2
BST1
OUTPUT1
1.8V
DH1
LX1
DL1
TON
BST2
DH2
LX2
DL2
PGND
OUTPUT2
2.5V
V+
MAX1715
Pin Configuration appears at end of data sheet.
OUT1
OUT2
PGOOD
SKIP
REF
FB1 AGND FB2
Quick-PWM is a trademark of Maxim Integrated Products.
________________________________________________________________
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 1-800-835-8769.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
