Rainbow-electronics MAX17061 Bedienungsanleitung PDF herunterladen (Seite 1)

General Description

The MAX17061 is a high-efficiency driver for white light-

emitting diodes (LEDs). It is designed for large liquid-

crystal displays (LCDs) that employ an array of LEDs as

the light source. An internal switch current-mode step-up

controller drives the LED array, which can be configured

for up to eight strings in parallel and 10 LEDs per string.

Each string is terminated with ballast that achieves ±1.5%

current-regulation accuracy between strings, ensuring

even LED brightness. The MAX17061 has a wide input-

voltage range from 4.5V to 26V, and provides a fixed

25mA or adjustable 15mA to 30mA full-scale LED current.

The MAX17061 internally generates a DPWM signal for

accurate WLED dimming control. The DPWM frequency

is resistor programmable, while DPWM duty cycle is con-

trolled directly from an external PWM signal or through a

control word through the MAX17061’s SMBus™ inter-

face. This DPWM control provides a dimming range with

8-bit resolution and supports Intel display-power-saving

technology (DPST) to maximize battery life.

The MAX17061 has multiple features to protect the con-

troller from fault conditions. Separate feedback loops

limit the output voltage under any circumstance, ensur-

ing safe operation. Once an open string is detected,

the string is disabled while other strings operate nor-

mally. The MAX17061 also features short LED detec-

tion. The shorted strings are also disabled after a 2ms

fault blanking interval. The controller features cycle-by-

cycle current limit to provide stable operation and soft-

start capability. If the MAX17061 is in current-limit

condition, the step-up converter is latched off after an

internal timer expires. A thermal-shutdown circuit pro-

vides another level of protection.

The MAX17061’s step-up controller features an internal

150mΩ (typ), 45V (max) power MOSFET with local cur-

rent-sense amplifier for accurate cycle-by-cycle current

limit. This architecture greatly simplifies the external cir-

cuitry and saves PCB space. Low-feedback voltage at

each LED string 625mV (typ) at 25mA LED current helps

reduce power loss and improve efficiency. The

MAX17061 features selectable switching frequency

(500kHz, 750kHz, or 1MHz), which enables a wide vari-

ety of applications that can trade off component size for

operating frequency.

The MAX17061 is available in a thermally enhanced

28-pin, 4mm x 4mm Thin QFN package.

Applications

Features

o Accurate Dimming Control Using SMBus, PWM

Interface

o Dimming Range with 8-Bit Resolution

o Adjustable DPWM Frequency with 1.5% Accuracy

o Up to Eight Parallel Strings Multiple Series-

Connected LEDs

o ±1.5% Current Regulation Accuracy Between

Strings

o Low String Feedback Voltage: 625mV at 25mA

LED Current

o Full-Scale LED Current Adjustable from 15mA to

30mA, or Preset 25mA

o Open and Short LED Protections

o Output Overvoltage Protection

o 0.15Ω Internal HV Power MOSFET (45V max)

o Wide Input-Voltage Range from 4.5V to 26V

o 500kHz/750kHz/1MHz Selectable Switching

Frequency

o Small 28-Pin, 4mm x 4mm, Thin QFN package

MAX17061

8-String White LED Driver with

SMBus for LCD Panel Applications

________________________________________________________________

Maxim Integrated Products

FB1

CCV

PGND1, 2

LX1, 2

FB2

FB3

FB4

FB5

FB6

FB7

FB8

ISET

FSET

PWMIPWM

MAX17061

OUT

SCLCLK

SDADATA

OSCN.C.

GND

PWMO

Simplified Operating Circuit

Ordering Information

19-3211; Rev 0; 1/08

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.

Denotes a lead-free package.

PART

TEMP RANGE

PIN-PACKAGE

MAX17061ETI+

-40

C to +85

28 Thin QFN (4mm x 4mm)

Pin Configuration appears at end of data sheet.

SMBus is a trademark of Intel Corp.

Notebook, Subnotebook,

and Tablet Computer

Displays

Automotive Systems

Handy Terminals

1 2 3 4 5 6 ... 25 26

MAX17061 1

Inhaltsverzeichnis

Seite 1 - MAX17061

General DescriptionThe MAX17061 is a high-efficiency driver for white light-emitting diodes (LEDs). It is designed for large liquid-crystal displays (

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications10 _____________________________________________________________________________

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications________________________________________________________________________________

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MAX17061The MAX17061 includes a 5V linear regulator that pro-vides the internal bias and gate drive for the step-upcontroller. When an external 5V is

Seite 5

MAX170618-String White LED Driver withSMBus for LCD Panel Applications________________________________________________________________________________

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MAX17061The MAX17061 includes power-on reset (POR) andundervoltage lockout (UVLO) features. POR resets thefault latch and sets all the SMBus registers

Seite 7

Frequency SelectionA tri-level OSC input sets the internal oscillator frequen-cy for step-up converter, as shown in Table 1. High-fre-quency (1MHz) op

Seite 8

MAX17061Full-Scale LED Brightnessin DPWM Dimming ControlThe full-scale LED current in the DPWM dimming isdetermined by resistance from the ISET pin to

Seite 9

Overvoltage ProtectionThe SMBus interface can be used to adjust the dim-ming, as well as shut down the MAX17061. Before theMAX17061 receives a turn-on

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications18 _____________________________________________________________________________

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The list of ID values for vendors is shown in Table 3.Thermal ShutdownThe MAX17061 includes a thermal-protection circuit.When the local IC temperature

Seite 12

ABSOLUTE MAXIMUM RATINGSELECTRICAL CHARACTERISTICS(Circuit of Figure 1, VIN= 12V, CCCV= 0.022µF, RCCV= 5.1kΩ, VISET= VOSC= VDD= VCC, RFSET= 464kΩ, VPW

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MAX17061To ensure the stable operation, the MAX17061 includesslope compensation, which sets the minimum inductorvalue. In continuous-conduction mode (

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The equations used here include a constant LIR, whichis the ratio of the inductor peak-to-peak ripple currentto the average DC inductor current at the

Seite 15

MAX17061The peak-inductor current at minimum input voltage iscalculated as follows:Alternatively, choosing a DCM operating mode at 750kHzand estimatin

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LED Selection and BiasThe series/parallel configuration of the LED load and thefull-scale bias current have a significant effect or regula-tor perform

Seite 17

MAX170614) Place the overvoltage detection divider resistors asclose as possible to the OV pin. The divider’s cen-ter trace should be kept short. Plac

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications________________________________________________________________________________

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MAX170618-String White LED Driver withSMBus for LCD Panel ApplicationsMaxim cannot assume responsibility for use of any circuitry other than circuitry

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications________________________________________________________________________________

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications4 ______________________________________________________________________________

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications________________________________________________________________________________

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications6 ______________________________________________________________________________

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications________________________________________________________________________________

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications8 ______________________________________________________________________________

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MAX170618-String White LED Driver withSMBus for LCD Panel Applications________________________________________________________________________________

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Rainbow-electronics MAX17061 Bedienungsanleitung Seite 1

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