Rainbow Electronics MAX8720 - Manual

General Description
The MAX8720 step-down controller is intended for core
CPU DC-DC converters in notebook computers. It fea-
tures a dynamically adjustable output, ultra-fast transient
response, high DC accuracy, and the 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 6-bit digital-to-analog converter (DAC) over a 0.275V
to 1.850V range in 25mV steps. The MAX8720 has inde-
pendent four-level logic inputs for setting the suspend
voltage (S0-S1). Precision slew-rate control provides
“just-in-time” arrival at the new DAC setting, minimizing
surge currents to and from the battery. The internal DAC
of the MAX8720 is synchronized to the slew-rate clock
for improved operation under aggressive power man-
agement of newer chipsets and operating systems that
can make incomplete mode transitions. Remote feed-
back and ground-sense inputs allow easy compensa-
tion for IR drops in PC board traces.
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 MAX8720 is available in a 28-pin QSOP or 36-pin
6mm x 6mm thin QFN package.
Applications
CPU Core Supply Converters
GPU Core Supply Converters
Notebook and Subnotebook Computers
Features
♦ Quick-PWM Architecture
♦ ±1% V
OUT Accuracy Over Line and Load
♦ 6-Bit On-Board DAC with Input Muxes
♦ Precision-Adjustable V
OUT Slew Control
♦ 0.275V to 1.850V Output Adjust Range
♦ Remote Feedback and Ground Sense
♦ Supports Voltage-Positioned Applications
♦ 2V to 28V Battery Input Range
♦ 200kHz/300kHz/550kHz/1000kHz Switching
Frequency
♦ Over/Undervoltage Protection
♦ Drives Large Synchronous-Rectifier FETs
♦ 800µA (typ) I
CC Supply Current
♦ 10µA (typ) Shutdown Supply Current
♦ 2V ±0.75% Reference Output
♦ PGOOD Blanking During Transition
MAX8720
Dynamically Adjustable 6-Bit VID
Step-Down Controller
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
MAX8720
PGOOD
VID0
VID1
VID2
VID3
VID4
VID5
SUS
AGND
OUTPUT (V OUT )
0.275V TO 1.850V
INPUT (V IN )
7V TO 28V
BST
V+
DH
LX
DL
PGND
FB
V CC V DD
SHDN
+5V BIAS
FBS
GNDS
CC
REF
TIME
SKIP
D0
D1
D2
D3
D4
D5
S0
S1
ILIM
Minimal Operating Circuit
19-3319; Rev 1; 8/04
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.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE PIN-PACKAGE
MAX8720EEI -40 °C to +85°C 28 QSOP
MAX8720ETX -40 °C to +85°C 36 Thin QFN 6mm x 6mm
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Pin Configurations appear at end of data sheet.