Rainbow-electronics MAX15026 Manual de usuario descargar pdf

General Description

The MAX15026 synchronous step-down controller oper-

ates from a 4.5V to 28V input voltage range and gener-

ates an adjustable output voltage from 85% of the input

voltage down to 0.6V while supporting loads up to 25A.

The device allows monotonic startup into a prebiased

bus without discharging the output and features adap-

tive internal digital soft-start.

The MAX15026 offers the ability to adjust the switching

frequency from 200kHz to 2MHz with an external resis-

tor. The MAX15026’s adaptive synchronous rectification

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 MAX15026 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 cur-

rent limit and thermal shutdown.

Sink-mode current limit prevents reverse inductor cur-

rent from reaching dangerous levels when the device is

sinking current from the output.

The MAX15026 is available in a space-saving and ther-

mally enhanced 3mm x 3mm, 14-pin TDFN-EP pack-

age. The MAX15026 operates over the -40°C to +85°C

temperature range.

Applications

Set-Top Boxes

LCD TV Secondary Supplies

Switches/Routers

Power Modules

DSP Power Supplies

Points-of-Load Regulators

Features

o 4.5V to 28V or 5V ±10% Input Supply Range

o 0.6V to (0.85 x V

) Adjustable Output

o Adjustable 200kHz to 2MHz Switching Frequency

o Ability to Start into a Prebiased Load

o Lossless, Cycle-by-Cycle Valley Mode Current

Limit with Adjustable, Temperature-Compensated

Threshold

o Sink-Mode Current-Limit Protection

o Adaptive Internal Digital Soft-Start

o ±1% Accurate Voltage Reference

o Internal Boost Diode

o Adaptive Synchronous Rectification Eliminates

External Freewheeling Schottky Diode

o Hiccup-Mode Short-Circuit Protection

o Thermal Shutdown

o Power-Good Output and Enable Input for Power

Sequencing

o ±5% Accurate Enable Input Threshold

MAX15026

Low-Cost, Small, 4.5V to 28V Wide Operating

Range, DC-DC Synchronous Buck Controller

________________________________________________________________

Maxim Integrated Products

*EP

DRV

LIM

MAX15026

DHIN

312

BSTPGOOD

GNDCOMP

RTFB

TDFN

(3mm x 3mm)

TOP VIEW

*EP = EXPOSED PAD.

Pin Configuration

Ordering Information

19-4108; Rev 0; 5/08

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.

EVALUATION KIT

AVAILABLE

PART TEMP RANGE

PIN-PACKAGE

MAX15026BETD+

-40°C to +85°C 14 TDFN-EP*

Denotes a lead-free package.

EP = Exposed pad.

1 2 3 4 5 6 ... 21 22

MAX15026 1

Indice de contenidos

Pagina 1 - MAX15026

General DescriptionThe MAX15026 synchronous step-down controller oper-ates from a 4.5V to 28V input voltage range and gener-ates an adjustable output

Pagina 2

MAX15026The adaptive driver dead-time allows operation withoutshoot-through with a wide range of MOSFETs, minimiz-ing delays and maintaining efficienc

Pagina 3

Current-Limit Circuit (LIM)The current-limit circuit employs a valley and sink cur-rent-sensing algorithm that uses the on-resistance ofthe low-side M

Pagina 4

MAX15026Sink current limit is implemented by monitoring the volt-age drop across the low-side MOSFET when LX is morepositive than GND. When the voltag

Pagina 5

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller___________________________________________________________

Pagina 6

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller14 ________________________________________________________

Pagina 7

requirements. Choose the small-signal components forthe error amplifier to achieve the desired closed-loopbandwidth and phase margin.To choose the app

Pagina 8

MAX15026Solving for CF:3) Place a high-frequency pole at fP1= 0.5 x fSW (toattenuate the ripple at the switching frequency, fSW)and calculate CCFusing

Pagina 9

The gain of the error amplifier (GAINEA) in midband fre-quencies is:GAINEA= 2π x fOx C1x RFThe total loop gain as the product of the modulator gainand

Pagina 10

MAX15026Boost Capacitor The MAX15026 uses a bootstrap circuit to generate thenecessary gate-to-source voltage to turn on the high-side MOSFET. The sel

Pagina 11

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller___________________________________________________________

Pagina 12

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller2 _________________________________________________________

Pagina 13

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller20 ________________________________________________________

Pagina 14

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller___________________________________________________________

Pagina 15

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck ControllerMaxim cannot assume responsibility for use of any circuitry

Pagina 16

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller___________________________________________________________

Pagina 17

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller4 _________________________________________________________

Pagina 18

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller___________________________________________________________

Pagina 19

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller6 _________________________________________________________

Pagina 20

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller___________________________________________________________

Pagina 21

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller8 _________________________________________________________

Pagina 22

MAX15026Low-Cost, Small, 4.5V to 28V Wide OperatingRange, DC-DC Synchronous Buck Controller___________________________________________________________

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