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MAX8650EEG

4.5V to 28V Input Current-Mode Step-Down Controller with Adjustable Frequency

Maxim Integrated 

19-3973; Rev 1; 8/08

EVAALVUAAILTAIOBNLEKIT 4.5V to 28V Input Current-Mode Step-

Down Controller with Adjustable Frequency

General Description

The MAX8650 synchronous PWM buck controller oper-

ates from a 4.5V to 28V input and generates an

adjustable 0.7V to 5.5V output voltage at loads up to 25A.

The MAX8650 uses a peak current-mode control archi-

tecture with an adjustable (200kHz to 1.2MHz) constant

switching frequency and is externally synchronizable. The

IC’s current limit uses the inductor’s DC resistance to

improve efficiency or an external sense resistor for high

accuracy. The current-limit threshold is adjusted with an

external resistor. Foldback-type current limit can be

implemented to reduce the power dissipation in overload

or short-circuit conditions. Short-circuit protection is

provided based on sensing the current in the low-side

MOSFET. A reference input is provided for use with a

high-accuracy external reference or for double-data-rate

(DDR)-tracking applications.

Monotonic prebiased startup is available for a safe-start

in applications where the output capacitor may have an

initial charge. This feature prevents the output from

pulling low during startup, which is a common charac-

teristic of conventional buck regulators.

A 180° out-of–phase synchronization output is available

for synchronizing with another converter.

Applications

Base Stations

DDR

Network and Telecom Power Modules

Storage

IBA Applications

Servers

Pin Configuration appears at end of data sheet.

Features

o Operates from 4.5V to 28V Supply

o 1% FB Voltage Accuracy Over Temperature

o Adjustable Output Voltage Down to 0.7V or REFIN

o Adjustable Switching Frequency or External

Synchronization from 200kHz to 1.2MHz

o 180° Phase-Shifted Clock Output

o Adjustable Overcurrent Limit

o Adjustable Foldback Current Limit

o Adjustable Slope Compensation

o Selectable Current-Limit Mode: Latch-Off or

Automatic Recovery

o Monotonic Output-Voltage Rise at Startup

o Output Sources and Sinks Current

o Enable Input

o Power-OK (POK) Output

o Adjustable Soft-Start

o Independently Adjustable Overvoltage Protection

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

MAX8650EEG+

-40°C to +85°C

24 QSOP

+Denotes a lead-free/RoHS-compliant package.

Typical Operating Circuit

R2

R1

SYNC

ON EN

OFF

POK

SYNCO

R3

C3

R4

C4

R5

R6

R7

1

FSYNC

11

EN

2

MODE

4

D2

BST

24

5

POK

DH

3

SYNCO

23

SCOMP

MAX8650EEG

6

C2

LX

DL 7

Q1

22

ILIM2

21

REFIN

20

SS

16

ILIM1

19

COMP

18

FB

8

Q2

PGND

VL 9

C7

10

C8

IN

C10

12

AVL

14

CS+

15 C11

CS-

17

OVP

13

GND

VIN

7V TO 28V

C1

L1

R8

C6

R9

VOUT

0.7V TO 5.5V

C5

C9

________________________________________________________________ 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.

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