19-1636; Rev 3; 8/05
KIT
ATION
EVALU
ILABLE
AVA
Dynamically Adjustable, Synchronous
Step-Down Controller for Notebook CPUs
The MAX1717 step-down controller is intended for core
CPU DC-DC converters in notebook computers. It features a dynamically adjustable output, ultra-fast transient response, high DC accuracy, and high efficiency
needed for leading-edge CPU core power supplies.
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 output voltage can be dynamically adjusted
through the 5-bit digital-to-analog converter (DAC)
inputs over a 0.925V to 2V range. A unique feature of
the MAX1717 is an internal multiplexer (mux) that
accepts two 5-bit DAC settings with only five digital
input pins. Output voltage transitions are accomplished
with a proprietary precision slew-rate control† that minimizes surge currents to and from the battery while
guaranteeing “just-in-time” arrival at the new DAC setting.
High DC precision is enhanced by a two-wire remotesensing scheme that compensates for voltage drops in
the ground bus and output voltage rail. Alternatively,
the remote-sensing inputs can be used together with
the MAX1717’s high DC accuracy to implement a voltage-positioned circuit that modifies the load-transient
response to reduce output capacitor requirements and
full-load power dissipation.
Single-stage buck conversion allows these devices 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.
Features
♦ Quick-PWM Architecture
♦ ±1% VOUT Accuracy Over Line and Load
♦ 5-Bit On-Board DAC with Input Mux
♦ Precision-Adjustable VOUT Slew Control
♦ 0.925V to 2V Output Adjust Range
♦ Supports Voltage-Positioned Applications
♦
♦
♦
♦
2V to 28V Battery Input Range
Requires a Separate +5V Bias Supply
200/300/550/1000kHz Switching Frequency
Over/Undervoltage Protection
♦ Drives Large Synchronous-Rectifier FETs
♦ 700µA (typ) ICC Supply Current
♦ 2µA (typ) Shutdown Supply Current
♦ 2V ±1% Reference Output
♦ VGATE Transition-Complete Indicator
♦ Small 24-Pin QSOP Package
Ordering Information
TEMP RANGE
PIN-PACKAGE
MAX1717EEG
PART
-40°C to +85°C
24 QSOP
MAX1717EEG+
-40°C to +85°C
24 QSOP
+ Denotes lead-free package.
Minimal Operating Circuit
BATTERY
2.5V TO 28V
MAX1717
+5V INPUT
The MAX1717 is available in a 24-pin QSOP package.
VCC
SKP/SDN
Applications
FBS
Notebook Computers with SpeedStep™ or
Other Dynamically Adjustable Processors
2-Cell to 4-Cell Li+ Battery to CPU Core Supply
Converters
5V to CPU Core Supply Converters
ILIM
GNDS
VDD
V+
BST
DH
OUTPUT
0.925V TO 2V
A/B
REF
TON
CC
Quick-PWM is a trademark of Maxim Integrated Products.
SpeedStep is a trademark of Intel Corp.
DL
D0
Pin Configuration appears at end of data sheet.
†P.
LX
DAC
INPUTS
D1
GND
D2
FB
D3
TIME
VGATE
D4
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
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MAX1717
General Description
