19-2661; Rev 1; 9/05
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
General Description
Features
The MAX1992/MAX1993 pulse-width modulation (PWM)
controllers provide high-efficiency, excellent transient
response, and high DC output accuracy. The devices
step down high-voltage batteries to generate low-
voltage CPU core or chipset/RAM supplies in notebook
computers.
♦ Inductor Saturation Protection
♦ Accurate Current Limit
♦ Ultra-High Efficiency
♦ Quick-PWM with 100ns Load-Step Response
♦ MAX1992
Maxim’s proprietary Quick-PWM™ quick-response, con-
stant 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. Efficiency is
enhanced by the ability to drive very large synchronous-
rectifier MOSFETs. Current sensing to ensure reliable
overload and inductor saturation protection is available
using an external current-sense resistor in series with the
output. Alternatively, the controller can sense the current
across the synchronous rectifier alone or use lossless
inductor sensing for lowest power dissipation.
1.8V/2.5V Fixed or 0.7V to 5.5V Adjustable
Output Range
♦ MAX1993
External Reference Input
Dynamically Selectable Output Voltage
(0.7V to 5.5V)
Optional Power-Good and Fault Blanking
During Transitions
♦
1ꢀ V
Accuracy Over Line and Load
OUT
♦ 2V to 28V Battery Input Range (V )
IN
♦ 200/300/450/600kHz Switching Frequency
♦ Overvoltage/Undervoltage Protection Option
♦ 1.7ms Digital Soft-Start
♦ Drives Large Synchronous Rectifier FETs
♦ 2V 0.7ꢀ Reference Output
Single-stage buck conversion allows the MAX1992/
MAX1993 to directly step down high-voltage batteries for
the highest possible efficiency. Alternatively, two-stage
conversion (stepping down from another system supply
rail instead of the battery) at the maximum switching fre-
quency allows the minimum possible physical size.
♦ Power-Good Window Comparator
The MAX1992 powers the CPU core, chipset, DRAM, or
other supply rails as low as 0.7V. The MAX1993 powers
chipsets and graphics processor cores, which require
dynamically adjustable output voltages. The MAX1993
provides a tracking input that can be used for active ter-
mination buses. The MAX1992/MAX1993 are available in
a 24-pin thin QFN package with optional overvoltage and
undervoltage protection.
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX1992ETG
-40°C to +85°C 24 Thin QFN 4mm × 4mm
MAX1992ETG+ -40°C to +85°C 24 Thin QFN 4mm × 4mm
MAX1993ETG -40°C to +85°C 24 Thin QFN 4mm × 4mm
MAX1993ETG+ -40°C to +85°C 24 Thin QFN 4mm × 4mm
+ Denotes lead-free package.
For dual step-down PWM controllers with inductor satu-
ration protection, external reference input voltage, and
dynamically selectable output voltages, refer to the
MAX1540/MAX1541 data sheet.
Pin Configurations
TOP VIEW
Applications
Notebook Computers
18
17 16
15 14
13
VDD
19
20
12 CSN
11
10 OUT
CSP
PGND
Core/IO Supplies as Low as 0.7V
1.8V and 2.5V Supplies
AGND 21
VCC 22
MAX1992
9
8
7
FB
DDR Memory Termination (MAX1993)
Active Termination Buses (MAX1993)
N.C.
23
24
SHDN
OVP/UVP
N.C
1
2
3
4
5
6
CPU/Chipset/GPU with Dynamic Voltage Cores
(MAX1993)
THIN QFN
4mm x 4mm
A "+" SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES.
Pin Configurations continued at end of data sheet.
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products
1
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.