Rainbow-electronics MAX17031 Bedienungsanleitung PDF herunterladen

General Description

The MAX17031 is a dual Quick-PWM™ step-down

power-supply (SMPS) controller with synchronous recti-

fication, intended for main 5V/3.3V power generation in

battery-powered systems. Low-side MOSFET sensing

provides a simple low-cost, highly efficient current

sense for valley current-limit protection. Combined with

the output overvoltage and undervoltage protection fea-

tures, this current limit ensures robust output supplies.

The 5V/3.3V SMPS outputs can save power by operat-

ing in pulse-skipping mode or in ultrasonic mode to

avoid audible noise. Ultrasonic mode forces the con-

troller to maintain switching frequencies greater than

20kHz at light loads. The SKIP input also has an accu-

rate logic threshold, allowing it to be used as a sec-

ondary feedback input to refresh an external charge

pump or secondary winding without overcharging the

output voltages.

An internal 100mA linear regulator generates the 5V

bias needed for power-up or other low-power “always-

on” suspend supplies. An internal bypass circuitry

allows automatic bypassing of the linear regulator when

the 5V SMPS is active.

The device includes independent shutdown controls

with well-defined logic thresholds to simplify power-up

and power-down sequencing. To prevent current

surges at startup, the internal voltage target is slowly

ramped up from zero to the final target over a 1ms peri-

od. To prevent the output from ringing below ground in

shutdown, the internal voltage target is ramped down

from its previous value to zero over a 1ms period. A

combined power-good (PGOOD) output simplifies the

interface with external controllers. The MAX17031 is

available in a 24-pin thin QFN (4mm x 4mm) package.

Applications

Notebook Computers

Ultra-Mobile PC

Main System Supply (5V and 3.3V Supplies)

2 to 4 Li+ Cells Battery-Powered Devices

Telecommunication

Features

o Dual Quick-PWM

o Preset 5V and 3.3V Outputs

o Internal 100mA, 5V Linear Regulator

o Internal OUT1 LDO5 Bypass Switch

o Secondary Feedback (SKIP Input) Maintains

Charge Pump

o 3.3V, 5mA Real-Time Clock (RTC) Power (Always

On)

o 2V ±1% 50µA Reference

o 6V to 24V Input Range

o Pulse-Skipping/Forced-PWM/Ultrasonic Mode

Control

o Independent SMPS and LDO5 Enable Controls

o Combined SMPS PGOOD Outputs

o Minimal Component Count

MAX17031

Dual Quick-PWM Step-Down Controller with Low-

Power LDO and RTC Regulator for MAIN Supplies

________________________________________________________________

Maxim Integrated Products

*EXPOSED PAD.

*EP

ONLDO

RTC

LDO5

REF

DL2

DL1

BST2

BST1

SKIP

456

1718 16 14 13

OUT2

ILIM2

ON1

PGOOD

ILIM1

OUT1

MAX17031

GND

ON2

DH1

DH2

LX1

LX2

THIN QFN

4mm × 4mm

TOP VIEW

Pin Configuration

Ordering Information

19-4305; Rev 0; 10/08

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

Denotes a lead-free/RoHS-compliant package.

EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

MAX17031ETG+ -40°C to +85°C 24 TQFN-EP*

Quick-PWM is a trademark of Maxim Integrated Products, Inc.

1 2 3 4 5 6 ... 23 24

MAX17031 1

Inhaltsverzeichnis

Seite 1 - MAX17031

General DescriptionThe MAX17031 is a dual Quick-PWM™ step-downpower-supply (SMPS) controller with synchronous recti-fication, intended for main 5V/3.3

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MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies10 _________________________________________________

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MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies____________________________________________________

Seite 4

MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies12 _________________________________________________

Seite 5

Detailed DescriptionThe MAX17031 step-down controller is ideal for high-voltage, low-power supplies for notebook computers.Maxim’s Quick-PWM pulse-wid

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MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies14 _________________________________________________

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MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies____________________________________________________

Seite 8

MAX17031The MAX17031 includes several features for multipur-pose notebook functionality, and is specificallydesigned for 5V/3.3V main power-supply rai

Seite 9

Modes of OperationForced-PWM Mode (VSKIP= 1.8V)The low-noise forced-PWM mode (VSKIP= 1.8V) dis-ables the zero-crossing comparator, which controls thel

Seite 10

MAX17031Secondary Feedback (SKIP)When the controller skips pulses (VSKIP> 2V), the longtime between pulses (especially if the output is sinkingcurr

Seite 11

Power-Good Outputs (PGOOD)and Fault ProtectionPGOOD is the open-drain output that continuouslymonitors both output voltages for undervoltage andovervo

Seite 12

MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies2 __________________________________________________

Seite 13

MAX17031Inductor Operating Point: This choice providestrade-offs between size vs. efficiency and transientresponse vs. output ripple. Low inductor val

Seite 14

In applications without large and fast load transients,the output capacitor’s size often depends on how muchESR is needed to maintain an acceptable le

Seite 15

MAX17031Power-MOSFET SelectionMost of the following MOSFET guidelines focus on thechallenge of obtaining high load-current capabilitywhen using high-v

Seite 16

Applications InformationStep-Down ConverterDropout PerformanceThe output voltage-adjustable range for continuous-conduction operation is restricted by

Seite 17

MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN SuppliesMaxim cannot assume responsibility for use of any ci

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MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies____________________________________________________

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MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies4 __________________________________________________

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MAX17031_______________________________________________________________________________________ 5Dual Quick-PWM Step-Down Controller with Low-Power LD

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MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies6 __________________________________________________

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MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies____________________________________________________

Seite 23

MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies8 __________________________________________________

Seite 24

MAX17031Dual Quick-PWM Step-Down Controller with Low-Power LDO and RTC Regulator for MAIN Supplies____________________________________________________

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Rainbow-electronics MAX17031 Bedienungsanleitung

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Inhaltsverzeichnis

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