MAX8655_09 Datasheet, PDF (1/23 Pages) Maxim Integrated Products – Highly Integrated, 25A, Wide-Input, Internal MOSFET, Step-Down Regulator

19-3982; Rev 1; 8/09
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Highly Integrated, 25A, Wide-Input,
Internal MOSFET, Step-Down Regulator
General Description
The MAX8655 synchronous-PWM buck regulator oper-
ates from a 4.5V to 25V input and generates an output
voltage adjustable from 0.7V to 5.5V at loads up to 25A.
Integrated power MOSFETs provide a small footprint,
ease of layout, and reduced EMI. Removing the board
trace inductances ensures the highest efficiency at
high frequency.
The MAX8655 uses peak current-mode control architec-
ture with an adjustable (200kHz to 1MHz), constant-
switching frequency, which is externally synchronizable.
The MAX8655’s adjustable current limit uses the induc-
tor’s DC resistance to improve efficiency or an external
sense resistor for higher accuracy. Foldback type cur-
rent limit is available to reduce the power dissipation
under severe-overload or short-circuit conditions. A ref-
erence input is provided for use with a high-accuracy
external reference or for DDR and tracking applications.
Monotonic startup provides safe starting into a prebi-
ased output, where traditional step-down regulators
discharge the output capacitor during soft-start, creat-
ing a negative voltage at the output and possibly dam-
aging the load.
A 180° out-of-phase synchronization output is available
for synchronizing with another MAX8655.
An enable input is provided for on/off control and to
facilitate output sequencing. Output-voltage sensing for
programmable overvoltage protection is provided and
is independent of the feedback network to further
enhance the output overvoltage protection.
Overall, the MAX8655 provides enough flexibility for the
experienced user, as well as simplicity and ease of use
for non-power-supply engineers.
Applications
Point-of-Load Power Supplies
Telecom Power
Networking
Nonisolated DC-DC Power Modules
Servers and Workstations
Notebook Computers
IBA Power Supplies
Ordering Information
PART
TEMP
RANGE
PIN-PACKAGE
MAX8655ETN+ -40°C to +85°C
56 TQFN-EP*
(8mm x 8mm)
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Features
o 25A Output Current
o Integrated Power MOSFETs
o Operates from 4.5V to 25V Supply
o 1% FB Voltage Accuracy Over Temperature
o Adjustable Output Voltage Down to 0.7V
o Adjustable Switching Frequency and External
Synchronization from 200kHz to 1MHz
o Multiphase Operation with Accurate Current
Sharing
o 180° Phase-Shifted Synchronization
o Adjustable Overcurrent Limit
o Adjustable Slope Compensation
o Selectable Current-Limit Mode: Latch-Off or
Automatic Recovery
o Monotonic Output Voltage Rise at Startup into
Prebias Output
o Output Sources and Sinks Current for DDR
Applications
o Enable Input
o Power-OK (POK) Output
o Adjustable Soft-Start
o Independently Adjustable Overvoltage Protection
Typical Operating Circuit
POWER-OK OUTPUT
POK
FSYNC INPUT
FSYNC
SYNC OUTPUT
ENABLE INPUT
ON
OFF
VL
INPUT 7V
TO 28V
SYNCO
EN
BST
LXB
PVIN
MAX8655
CS-
CS+
PVIN
IN
VL
VLGND
LX
AVL
Pin Configuration appears at end of data sheet.
OUTPUT
0.7V TO 5.5V
UP TO 25A
________________________________________________________________ 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.