MAX1718T_08 Datasheet, PDF (1/34 Pages) Maxim Integrated Products – Notebook CPU Step-Down Controller

19-2682; Rev 1; 10/08
Notebook CPU Step-Down Controller
General Description
The MAX1718T step-down controller is intended for core
CPU DC-to-DC converters in notebook computers. It fea-
tures a dynamically adjustable output, ultra-fast transient
response, high-DC accuracy, and high efficiency need-
ed 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) over
a 0.6V to 1.75V range. The MAX1718T has an internal
multiplexer that accepts three unique 5-bit VID DAC
codes corresponding to performance, battery, and sus-
pend modes. Precision slew-rate control provides “just-
in-time” arrival at the new DAC setting, minimizing
surge currents to and from the battery.
A pair of complementary offset control inputs allows
easy compensation for IR drops in PCB traces or cre-
ation of a voltage-positioned power supply. Voltage
positioning modifies the load-transient response to
reduce output capacitor requirements and total system
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 mini-
mum possible physical size.
The MAX1718T is available in a 28-pin QSOP package.
Applications
2-Cell to 4-Cell Li+ Battery to CPU Core Supply
Converters
5V to CPU Core Supply Converters
Features
o Quick-PWM Architecture
o ±1% V_OUT Accuracy Over Line and Load
o 5-Bit On-Board DAC with Input Muxes
o Precision-Adjustable V_OUT Slew Control
o 0.6V to 1.75V Output Adjust Range
o Precision Offset Control
o Supports Voltage-Positioned Applications
o 2V to 28V Battery Input Range
o Requires a Separate 5V Bias Supply
o 200kHz/300kHz/550kHz/1000kHz Switching
Frequency
o Overvoltage/Undervoltage Protection
o Drives Large Synchronous-Rectifier FETs
o 700µA (typ) I_CC Supply Current
o 2µA (typ) Shutdown Supply Current
o 2V ±1% Reference Output
o VGATE Blanking During Transition
o Small 28-Pin QSOP Package
Ordering Information
PART
MAX1718TEEI
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
28 QSOP
Minimal Operating Circuit
SHUTDOWN
DUAL MODE™ VID
MUX INPUTS
MUX CONTROL
SUSPEND
INPUT
DECODER
5V INPUT
V_CC
SKP/SDN
ILIM
V_DD
V+
BST
MAX1718T DH
D0
D1
LX
D2
D3
DL
D4
GND
ZMODE
SUS
S0
S1
FB
TIME
NEG
CC
POS
BATT 2V TO 28V
OUTPUT
0.6V TO 1.75V
VCC
Pin Configuration appears at end of data sheet.
REF
VGATE
TON
OVP
POWER-GOOD
OUTPUT
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Dual Mode is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.