MAX17149ETE+ Maxim Integrated Products, MAX17149ETE+ Datasheet

MAX17149ETE+

Manufacturer Part Number

MAX17149ETE+

Description

LED Drivers 6-String WLED Driver

Manufacturer

Maxim Integrated Products

Datasheet

1.MAX17129ETE.pdf (20 pages)

Specifications of MAX17149ETE+

Operating Supply Voltage

3 V to 26 V

Maximum Supply Current

4 mA

Maximum Power Dissipation

1176 mW

Maximum Operating Temperature

+ 85 C

Mounting Style

SMD/SMT

Package / Case

TQFN-16

Minimum Operating Temperature

- 40 C

Lead Free Status / RoHS Status

Lead free / RoHS Compliant

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Download datasheet (2Mb)

19-5676; Rev 0; 12/10

The MAX17129/MAX17149 are high-efficiency drivers for

white light-emitting diodes (LEDs). They are designed for

small- to medium-sized liquid-crystal displays (LCDs) that

employ an array of LEDs as the light source. An internal

switch step-up controller with Quick-PWMK control archi-

tecture drives the LED array, which can be configured for

up to 6 strings in parallel and either 11 LEDs (MAX17129)

or 6 LEDs in series (MAX17149) per string. Each string

is terminated with a ballast that achieves Q2% current-

regulation accuracy, ensuring even LED brightness and

provides an adjustable 10mA to 45mA full-scale LED

current. The devices have a wide input voltage range of

6V to 26V. The MAX17129 integrates an LDO to simplify

applications that have a single high-voltage supply. The

devices also feature a low-input-voltage mode for appli-

cations that have a 3V to 5.5V supply voltage.

These devices support PWM dimming mode. The exter-

nal PWM signal directly controls the brightness of LEDs.

The dimming frequency can range from 100Hz to 25kHz

with 400ns minimum on-time.

The devices have multiple features to protect the con-

troller from fault conditions. Separate voltage-feedback

loops limit the output voltage to safe operation. The open

and short-LED detection shuts down the faulty string

while keeping other strings operating normally.

The devices feature cycle-by-cycle current limit on the

internal switch to provide consistent operation and soft-

start capability. If the devices are in current-limit condi-

tion, the step-up converter is latched off after an internal

timer expires. A thermal-shutdown circuit provides anoth-

er level of protection and prevents ICs from damage.

The ICs’ step-up controller features an internal 0.245I

(typ), 48V (max) power MOSFET with lossless current

sense and accurate cycle-by-cycle current limit. The

Quick-PWM control architecture provides fast load-tran-

sient response without requiring an external loop com-

pensation component, simplifies the external circuitry, and

saves board area. The Quick-PWM control scheme has

constant off-time and adjustable pseudo-fixed frequency,

which enables a wide variety of applications that can trade

off component size for operating frequency. Low feedback

voltage at each LED string (275mV typ at 20mA LED cur-

rent) helps reduce power loss and improve efficiency.

The ICs are available in a 16-pin, thin QFN package with

0.5mm lead spacing. The package is 3mm x 3mm with a

maximum thickness of 0.8mm for ultra-thin LCD panel design.

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

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.

_______________________________________________________________ Maxim Integrated Products 1

General Description

Low-Cost, 6-String WLED Drivers with

Quick-PWM Step-Up Converter

S 3V to 26V Input Supply Voltage

S Up to Six Parallel Strings of Multiple Series-

S Step-Up Regulator with Quick-PWM Control Scheme

S Two-Level Selectable Switching Frequency

S 0.245I Internal HV Power MOSFET (48V max)

S Low String Feedback Voltage: 275mV at 20mA

S Full-Scale LED Current Adjustable from 10mA to

S ±2% Current Regulation Accuracy Between Strings

S Support PWM Dimming Mode

S 100:1 Dimming Ratio

S 100Hz to 25kHz Dimming Frequency for PWM

S Open and Short LED Protection

S Output Overvoltage Protection

S Small 16-Pin, 3mm x 3mm Thin QFN Package

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

*EP = Exposed pad.

Simplified Operating Circuit appears at end of data sheet.

MAX17129ETE +

MAX17149ETE+

Connected LEDs

LED Current

45mA

Dimming Mode

Notebook, Subnotebook, and Tablet Computer

Displays

Automotive Systems

Handy Terminals

PART

-40°C to +85°C

TEMP RANGE

Ordering Information

Applications

PIN-PACKAGE

16 Thin QFN-EP*

Features

Related parts for MAX17149ETE+

MAX17149ETE+ Summary of contents

Page 1

... S Output Overvoltage Protection S Small 16-Pin, 3mm x 3mm Thin QFN Package Notebook, Subnotebook, and Tablet Computer Displays Automotive Systems Handy Terminals PART MAX17129ETE + MAX17149ETE+ +Denotes lead(Pb)-free/RoHS-compatible package. *EP = Exposed pad. Simplified Operating Circuit appears at end of data sheet. Features Applications Ordering Information TEMP RANGE ...

Page 2

Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter ABSOLUTE MAXIMUM RATINGS FSEL, IN, BRT GND ..................................-0.3V to +28V FB_, LX, OVP to PGND .........................................-0.3V to +48V PGND to GND ......................................................-0.3V to +0. GND .............................................................-0.3V to +6V ...

Page 3

Low-Cost, 6-String WLED Drivers with ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 12V 100kI ISET PARAMETER 0.3V < V FSEL Bias Current 4.1V < V LED CURRENT SOURCE ISET Resistance Range R ISET R ...

Page 4

Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter ELECTRICAL CHARACTERISTICS (Circuit of Figure 12V 100kI ISET PARAMETER IN not connected Input Voltage Range Quiescent ...

Page 5

Low-Cost, 6-String WLED Drivers with ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 12V 100kI ISET PARAMETER FB_ On-Resistance V FB_ V FB_ FB_ Leakage Current V FB_ FB_ On-Time BRT Input High Level BRT ...

Page 6

Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter (Circuit of Figure 12V +25°C, unless otherwise noted LED CURRENT (I LED 100% BRIGHTNESS) vs. INPUT VOLTAGE 20.20 20.15 20.10 20.05 20. ...

Page 7

Low-Cost, 6-String WLED Drivers with (Circuit of Figure 12V +25°C, unless otherwise noted LED OPEN FAULT PROTECTION (BRIGHTNESS = 100%, LED OPEN ON FB1) 20mA 2ms/div LINE TRANSIENT RESPONSE = 9V ↔ 21V, ...

Page 8

Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter PIN NAME PWM Signal Input. This PWM signal controls the LED brightness by turning the LED current sources on 1 BRT or off. Internal LDO Output. V Connect a minimum 1FF capacitor ...

Page 9

Low-Cost, 6-String WLED Drivers with PIN NAME Current-Balancer Output. LED string cathode connection. FB3 is the open-drain output of an internal 10 FB3 regulator, which controls current through FB3. FB3 can sink up to 45mA. If unused, connect FB3 to ...

Page 10

Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter 26V C IN 4.7µF IN 0.1µ 1µF ISET R ISET 100kI EN BRT 100Hz TO 25kHz GND Figure 1. MAX17129 Typical Operating Circuit Table 1. Component ...

Page 11

Low-Cost, 6-String WLED Drivers with EN STARTUP IN 3.8V LDO V CC LOGIC-CIRCUIT SUPPLY CALCULATION FSEL FAULT CONTROL THERMAL SHUTDOWN ISET ISET EN BRT TEST AND OTP SMBus Figure 2. Functional Diagram Quick-PWM Step-Up Converter OFF-TIME ONE-SHOT ...

Page 12

Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter Detailed Description The MAX17129/MAX17149 are high-efficiency drivers for arrays of white LEDs. They contain a Quick-PWM step-up controller, a 3.8V linear regulator, PWM dimming control circuit, internal power MOSFET, and six regulated ...

Page 13

Low-Cost, 6-String WLED Drivers with The actual switching frequency can be approximated by: − × × − I OFF OVP D where the forward voltage of ...

Page 14

Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter Figure 5 shows possible supply connection configura- tions for the devices. The V pin should be bypassed CC to GND with a minimum 1FF ceramic capacitor. At startup, the devices perform an ...

Page 15

Low-Cost, 6-String WLED Drivers with Current-Source Fault Protection An LED fault open/short is detected after the startup. When one or more strings fail after the startup, the corre- sponding current source is disabled. The remaining LED strings still operate normally. ...

Page 16

Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter inductor resistance is relatively high, more ripples can be accepted to reduce the number of required turns and increase the wire diameter. If the inductor resistance is relatively low, increasing inductance to ...

Page 17

Low-Cost, 6-String WLED Drivers with Output Capacitor Selection The total output-voltage ripple has two components: the capacitive ripple caused by the charging and discharging on the output capacitor, and the ohmic ripple due to the capacitor’s equivalent series resistance (ESR): ...

Page 18

Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter PCB Layout Guidelines Careful PCB layout is important for proper operation. Use the following guidelines for good PCB layout: 1) Minimize the area of high current-switching loop of the rectifier diode, internal ...

Page 19

Low-Cost, 6-String WLED Drivers with Chip Information PROCESS: BiCMOS Quick-PWM Step-Up Converter FSEL PGND CC MAX17129 ISET OVP FB1 FB2 FB3 EN FB4 BRT FB5 GND FB6 EP For the latest package outline information and land pat ...

Page 20

... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 20 2010 Maxim Integrated Products © ...

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