MAX8686 Datasheet, PDF (1/23 Pages) Maxim Integrated Products – Single/Multiphase, Step-Down, DC-DC Converter Delivers Up to 25A Per Phase

19-4113; Rev 1; 10/10
Single/Multiphase, Step-Down,
DC-DC Converter Delivers Up to 25A Per Phase
General Description
The MAX8686 current-mode, synchronous PWM step-
down regulator with integrated MOSFETs operates from
a 4.5V to 20V input supply and generates an adjustable
output voltage from 0.7V to 5.5V while delivering up to
25A per phase.
The MAX8686 employs a peak current-mode architec-
ture that operates with an adjustable switching frequency
from 300kHz to 1MHz. An adjustable current-limit thresh-
old allows for optimization for different applications with
different load currents. Inductor current sense is
achieved either using an external sense resistor or using
a lossless inductor current-sense scheme. The foldback
and hiccup current limit reduces the power dissipation
during overload or short-circuit conditions and allows for
autorecovery when the fault condition is removed.
The MAX8686 offers the ability to start up monotonically
even when there is a prebias output voltage. In addi-
tion, an adjustable soft-start capability allows for a con-
trolled turn-on. The MAX8686 features an accurate 1%
reference and offers a reference input that allows for a
higher accuracy reference to be used for voltage track-
ing applications such as DDR memory.
The MAX8686 can be paralleled (up to eight) together
in a true multiphase mode to deliver up to 200A of out-
put current. When operating in this mode, this device
achieves better than 10% current balance between
phases at full load. The MAX8686 supports program-
mable phase shedding to improve system efficiency
during light load conditions.
Other features include an enable input and a power-OK
(POK) indicator used for power sequencing. The
MAX8686 also features latch overvoltage protection
that turns on the low-side MOSFET when the output
voltage exceeds 120% of the nominal voltage. The
MAX8686 is offered in a thermally enhanced 40-pin,
6mm x 6mm TQFN package.
Applications
POL Power Supplies
Module Replacements
Telecom Equipment
Networking Equipment
Servers
DDR Memory
Pin Configuration appears at end of data sheet.
Features
o Operating Range from 4.5V to 20V Input Supply
o 1% Reference Voltage Accuracy Over Temperature
o Reference Input (REFIN) for Output Tracking or
System Reference Voltage
o Adjustable Switching Frequency from 300kHz
to 1MHz
o Single/Multiphase Operation Delivers Up to
25A/200A with Integrated MOSFETs
o Adjustable Current Limit
o Monotonic Output Voltage at Startup (Prebias)
o Output Sink and Source Current Capability
o Adjustable Soft-Start
o Thermal-Overload Protection
o Output Overvoltage Protection
o Thermally Enhanced 6mm x 6mm TQFN
Package (4W)
Ordering Information
PART
TEMP RANGE
MAX8686ETL+
-40°C to +85°C
+Denotes a lead-free package.
*EP = Exposed pad.
PIN-PACKAGE
40 TQFN-EP*
Typical Application Circuit
VIN = 12V
ENABLE
INPUT
IN
BST
PGND
LX
RS+
REFIN _MAX8686
RS-
PHASE/REFO
CS+
COMP
CS-
POK
EN/SLOPE
FREQ SS GND
ILIM
VOUT = 1.2V/25A
POK
OUTPUT
________________________________________________________________ Maxim Integrated Products 1
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