MAX1992_05 Datasheet, PDF (1/36 Pages) Maxim Integrated Products – Quick-PWM Step-Down Controllers

19-2661; Rev 1; 9/05
Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
General Description
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.
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.
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.
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.
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.
Applications
Notebook Computers
Core/IO Supplies as Low as 0.7V
1.8V and 2.5V Supplies
DDR Memory Termination (MAX1993)
Active Termination Buses (MAX1993)
CPU/Chipset/GPU with Dynamic Voltage Cores
(MAX1993)
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Features
♦ Inductor Saturation Protection
♦ Accurate Current Limit
♦ Ultra-High Efficiency
♦ Quick-PWM with 100ns Load-Step Response
♦ MAX1992
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
♦ ±1% V_OUT Accuracy Over Line and Load
♦ 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 ±0.7% Reference Output
♦ Power-Good Window Comparator
Ordering Information
PART
MAX1992ETG
MAX1992ETG+
MAX1993ETG
MAX1993ETG+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
24 Thin QFN 4mm × 4mm
24 Thin QFN 4mm × 4mm
24 Thin QFN 4mm × 4mm
24 Thin QFN 4mm × 4mm
+ Denotes lead-free package.
Pin Configurations
TOP VIEW
18 17 16 15 14 13
VDD 19
12 CSN
PGND 20
11 CSP
AGND 21
VCC 22
MAX1992
10 OUT
9 FB
SHDN 23
8 N.C.
OVP/UVP 24
7 N.C
1 23 45 6
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.
________________________________________________________________ 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.