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40V, High-Performance, Synchronous

Buck Controller

General Description

The MAX15046 synchronous step-down controller oper-

ates from a 4.5V to 40V input voltage range and gener-

ates an adjustable output voltage from 85% of the input

voltage down to 0.6V, supporting loads up to 25A. The

device allows monotonic startup into a prebiased bus

without discharging the output and features adaptive

internal digital soft-start.

The MAX15046 offers the ability to adjust the switching

frequency from 100kHz to 1MHz with an external resis-

tor. The MAX15046’s adaptive synchronous rectifica-

tion eliminates the need for an external freewheeling

Schottky diode. The device also utilizes the external

low-side MOSFET’s on-resistance as a current-sense

element, eliminating the need for a current-sense resis-

tor. This protects the DC-DC components from damage

during output overloaded conditions or output short-

circuit faults without requiring a current-sense resistor.

Hiccup-mode current limit reduces power dissipation

during short-circuit conditions. The MAX15046 includes

a power-good output and an enable input with precise

turn-on/turn-off threshold, which can be used for input

supply monitoring and for power sequencing.

Additional protection features include sink-mode current

limit, and thermal shutdown. Sink-mode current limit pre-

vents reverse inductor current from reaching dangerous

levels when the device is sinking current from the output.

The MAX15046 is available in a 16-pin QSOP or 16-pin

QSOP-EP package and operates over the -40NC to +125NC

temperature range.

Features

S

Input Voltage Ranges from 4.5V to 40V or 5V

Q

10%

S

S

Adjustable Switching Frequency (100kHz to 1MHz)

with Q10% (1MHz) Accuracy

S

Adaptive Internal Digital Soft-Start

S

Up to 25A Output Capability

S

Cycle-by-Cycle Valley-Mode Current Limit with

Adjustable, Temperature-Compensated Threshold

(30mV to 300mV)

S

Monotonic Startup into Prebiased Output

S

Q

1% Accurate Voltage Reference

S

3A-Peak Gate Drivers

S

Hiccup-Mode Short-Circuit Protection (Patent-

Pending Architecture)

S

Overtemperature Shutdown

S

Power-Good (PGOOD) Output and Enable Input

(EN) with Q5% Accurate Threshold

S

Thermally Enhanced 16-Pin QSOP Package

Applications

Industrial Power Supplies (PLC, Industrial

Computers, Fieldbus Components, Fieldbus

Couplers)

Telecom Power Supplies

Base Stations

19-4719; Rev 0; 7/09

Pin Configurations appear at end of data sheet.

Ordering Information

+Denotes a lead(Pb)-free/RoHS-compliant package.

*EP = Exposed pad.

Typical Operating Circuit

MAX15046

IN

DH

CSP

LX

BST

DL

DRV

PGND

GND

C1

Q1

Q2

PGOOD

EN

LIM

COMP

FB

RT

L1

D1

R5

C4

C3

C2

R2

R3

R3

C6

C5

R4

4.5V TO 40V

ON

OFF

C7

R1

PART

TEMP RANGE

PIN-PACKAGE

MAX15046AAEE+

16 QSOP

MAX15046BAEE+

16 QSOP-EP*