19-2010; Rev 0; 4/01
Dynamically-Adjustable, Synchronous Step-Down
Controller with Integrated Voltage Positioning
General Description
Features
The MAX1813 step-down controller is intended for core
CPU DC-DC converters in notebook computers. The
controller features a dynamically adjustable output (5-
bit DAC), ultra-fast transient response, high DC accura-
cy, and high efficiency necessary 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 switch-
ing frequency.
ꢀ High-Efficiency Voltage Positioning
ꢀ Quick-PWM Architecture
ꢀ ±±1 V
Accuracy Over Line
OUT
ꢀ Adjustable Output Slew Rate
ꢀ 0.600V to 2V Adjustable Output Range (5-Bit DAC)
ꢀ 2V to 28V Battery Input Range
ꢀ 200/300/600/±000kHz Switching Frequency
ꢀ Output Undervoltage and Overvoltage Protection
ꢀ Drives Large Synchronous-Rectifier MOSFETs
ꢀ ±201 Accurate Current-Liꢀit
The MAX1813 is designed specifically for CPU core
applications requiring a voltage-positioned supply. The
voltage-positioning input (VPCS), combined with a
high-DC-accuracy control loop, is used to implement a
power supply that modifies its output set point in
response to the load current. This arrangement
decreases full-load power dissipation and reduces the
required number of output capacitors.
ꢀ ±0µA Shutdown Supply Current
ꢀ 2V ±±1 Reference Output
ꢀ Power-Good (PGOOD) Indicator
The output voltage can be dynamically adjusted
through the 5-bit digital-to-analog converter (DAC)
inputs over a 0.600V to 2V range. The MAX1813
includes an internal multiplexer that selects between
three different DAC code settings. The first two inputs
are controlled by five digital input pins (D0–D4). The
third input is used for the suspend mode and controlled
by two 4-level input pins (S0, S1). Output voltage transi-
tions 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.
ꢀ Sꢀall 28-Pin QSOP Package
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
28 QSOP
MAX1813EEI
-40°C to +85°C
Pin Configuration
TOP VIEW
V+
VPCS
SKP/SDN
TIME
FB
1
2
3
4
5
6
7
8
9
28 DH
27 LX
26 BST
25 D0
24 D1
The MAX1813’s 28V input range enables single-stage
buck conversion from high-voltage batteries for the
maximum possible efficiency. Alternatively, the con-
troller’s high-frequency capability combined with two-
stage conversion (stepping down the +5V system
supply instead of the battery) allows the smallest possi-
ble physical size.
MAX1813
CC
23 D2
S0
22 D3
S1
21 D4
The MAX1813 is available in a 28-pin QSOP package.
V
CC
20 CODE
19 ZMODE
18 SUS
Applications
TON 10
REF 11
Notebook Computers
(Intel IMVP–II™/Coppermine™)
Docking Stations
ILIM 12
17 V
DD
PGOOD 13
GND 14
16 DL
15 PGND
CPU Core Supply
QSOP
Single-Stage (BATT to V ) Converters
CORE
Two-Stage (+5V to V
) Converters
CORE
Typical Operating Circuit appears at end of data sheet.
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Coppermine and IMVP-ΙΙ are trademarks of Intel Corp.
________________________________________________________________ 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.