MAX8855_11 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – Dual, 5A, 2MHz Step-Down Regulators Integrated Boost Diodes

19-0726; Rev 3; 7/11
EVAALVUAAILTAIOBNLEKIT _{Dual, 5A, 2MHz Step-Down Regulators}
General Description
The MAX8855/MAX8855A high-efficiency, dual step-down
regulators are capable of delivering up to 5A at each out-
put. The devices operate from a 2.30V to 3.6V supply, and
provide output voltages from 0.6V to 0.9 x V_IN, making them
ideal for on-board point-of-load applications. Total output
error is less than ±1% over load, line, and temperature.
The MAX8855/MAX8855A operate in PWM mode with a
switching frequency ranging from 0.5MHz to 2MHz, set
by an external resistor. It can also be synchronized to
an external clock in the same frequency range. Two
internal switching regulators operate 180° out-of-phase
to reduce the input ripple current, and consequently
reduce the required input capacitance. The high
operating frequency minimizes the size of external
components. High efficiency, internal dual-nMOS
design keeps the board cool under heavy loads. The
voltage-mode control architecture and the high-band-
width (> 15MHz typ) voltage-error amplifier allow a type
III compensation scheme to be utilized to achieve fast
response under both line and load transients, and also
allow for ceramic output capacitors.
Programmable soft-start reduces input inrush current.
Two enable inputs allow the turning on/off of each out-
put individually, resulting in great flexibility for system-
level designs. A reference input is provided to facilitate
output-voltage tracking applications. The MAX8855/
MAX8855A are available in a 32-pin TQFN (5mm x 5mm)
package with 0.8mm max height.
Applications
ASIC/CPU/DSP Power Supplies
DDR Power Supplies
Set-Top Box Power Supplies
Printer Power Supplies
Network Power Supplies
Features
o 27mΩ On-Resistance Internal MOSFETs
o Dual, 5A, PWM Step-Down Regulators
o Fully Protected Against Overcurrent,
Short Circuit, and Overtemperature
o ±1% Output Accuracy Over Load, Line,
and Temperature
o Operates from 2.30V to 3.6V Supply
o REFIN on One Channel for Tracking or
External Reference
o Integrated Boost Diodes
o Adjustable Output from 0.6V to 0.9 x V_IN
o Soft-Start Reduces Inrush Supply Current
o 0.5MHz to 2MHz Adjustable Switching,
or FSYNC Input
o All-Ceramic-Capacitor Design
o 180° Out-of-Phase Operation Reduces Input
Ripple Current
o Individual Enable Inputs and PWRGD Outputs
o Safe-Start into Prebiased Output
o Available in 5mm x 5mm Thin QFN Package
o Sink/Source Current in DDR Applications
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX8855ETJ+
-40°C to +85°C 32 TQFN-EP*
MAX8855AETJ+
-40°C to +85°C 32 TQFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Typical Operating Circuit
OUTPUT1
1.2V / 5A
INPUT1
2.30V TO 3.6V
IN1 IN2
BST1
BST2
LX1
LX2
INPUT2
2.30V TO 3.6V
OUTPUT2
1.5V / 5A
PGND1 PGND2
MAX8855/
MAX8855A
FB1
FB2
Pin Configuration appears at end of data sheet.
TYPE III
COMPENSATION
ON
OFF
COMP1 COMP2
PWRGD1 PWRGD2
EN1
EN2
GND
TYPE III
COMPENSATION
ON
OFF
________________________________________________________________ Maxim Integrated Products 1
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or visit Maxim’s website at www.maxim-ic.com.