max8879etg Maxim Integrated Products, Inc., max8879etg Datasheet

max8879etg

Manufacturer Part Number

max8879etg

Description

Charge Pump For Backlight/flash/rgb Leds With Safety Timer

Manufacturer

Maxim Integrated Products, Inc.

Datasheet

1.MAX8879ETG.pdf (16 pages)

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The MAX8879 provides complete light management for

main display backlight, subdisplay backlight (or RGB

indicator), and white LED camera flash with regulated

constant current up to 610mA total. By utilizing adap-

tive 1x/1.5x/2x charge-pump modes and very-low-

dropout current regulators, it achieves high efficiency

over the full 1-cell Li+ battery input voltage range. The

1MHz fixed-frequency switching allows for tiny external

components while the regulation scheme is optimized

to ensure low EMI and low input ripple. An integrated

derating function protects the LEDs from overheating

during high ambient temperatures.

The MAX8879 features an internally trimmed reference

to set the maximum LED current. An I

used for on/off control and setting the LED currents in

32 linear steps for main, sub/RGB, and movie. When

using the RGB indicator, the I

ors and programmable ramp-up/down rates. The cam-

era flash for flash-mode operation is enabled by an

active-low signal on the FSH pin. A safety timer is acti-

vated on the falling edge of FSH, which has an I

adjustable (programmable) period of no timer, 0.5s,

1.0s, or 2.0s (default). If the safety timer period expires,

both flash and movie modes are disabled.

19-4266; Rev 0; 9/08

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.

Cell Phones and Smartphones

PDAs, Digital Cameras, Camcorders

Displays with Up to 11 LEDs

Charge Pump for Backlight/Flash/RGB LEDs

________________________________________________________________ Maxim Integrated Products

BRIGHTNESS

ON/OFF AND

INPUT

2.7V TO 5.5V

4.7μF

LOGIC

General Description

C PORT

ON/OFF

0.1μF

FLASH

C port provides 32k col-

GND

SCK

SDA

FSH

Applications

C1P

1μF

C serial port is

C1N

MAX8879

PGND

C2P

1μF

C2N

C-

OUT

OUTPUT

UP TO 610mA

♦ Guaranteed 610mA Continuous Drive Capability

♦ 2-Wire I

♦ 92% Peak/83% Avg Efficiency (P

♦ Adaptive 1x/1.5x/2x Mode Switchover

♦ 0.3% (typ) LED Current Accuracy and Matching

♦ Low Input Ripple and EMI

♦ Low 0.1µA Shutdown Current

♦ Output Overvoltage Protection

♦ I

♦ Thermal Derating Function Protects LEDs

♦ 24-Pin, 4mm x 4mm Thin QFN Package

Pin Configuration appears at end of data sheet.

+ Denotes a lead-free/RoHS-compliant package.

10μF

MAX8879ETG+

C Programmable Flash Safety Timer

4 LEDs at 30mA Each for Main Display

3 LEDs at 30mA Each for Sub or RGB

400mA Total for Flash

5-Bit (32-Step) Linear Dimming

32k Colors

Ramp-Up/Down Rates

PART

MAIN

C Serial Port

with Safety Timer

Typical Operating Circuit

SUB OR RGB

-40°C to +85°C

TEMP RANGE

Ordering Information

FLASH

LED

PIN-

PACKAGE

24 Thin QFN

4mm x 4mm

Features

BATT

)

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max8879etg Summary of contents

Page 1

... Output Overvoltage Protection ♦ Programmable Flash Safety Timer ♦ Thermal Derating Function Protects LEDs ♦ 24-Pin, 4mm x 4mm Thin QFN Package 2 C- PART Applications MAX8879ETG+ Pin Configuration appears at end of data sheet. + Denotes a lead-free/RoHS-compliant package. 1μF 1μF OUTPUT C1P C1N C2P C2N ...

Page 2

Charge Pump for Backlight/Flash/RGB LEDs with Safety Timer ABSOLUTE MAXIMUM RATINGS , IN, PIN, SCK, SDA, FSH, OUT to GND .........-0.3V to +6. M_, S_ GND ....................................-0. C1N, C2N to GND .......................................-0. ...

Page 3

Charge Pump for Backlight/Flash/RGB LEDs ELECTRICAL CHARACTERISTICS (continued 3.6V 1.8V PIN DD GND +25°C, unless otherwise noted.) (Note 1) PARAMETER Input Voltage Mode Transition Hysteresis M_, S_, F_ Leakage in ...

Page 4

Charge Pump for Backlight/Flash/RGB LEDs with Safety Timer (T = +25°C, unless otherwise noted.) A EFFICIENCY vs. SUPPLY VOLTAGE DRIVING 4 MAIN LEDs 100 30mA/LED 50 15mA/LED 40 1.9mA/LED SUPPLY VOLTAGE FALLING 0 ...

Page 5

Charge Pump for Backlight/Flash/RGB LEDs (T = +25°C, unless otherwise noted.) A OPERATING WAVEFORMS 1X MODE V OUT 1μs/div OPERATING WAVEFORMS 2X MODE V OUT 1μs/div MAIN STARTUP WITH RGB ALREADY ON ...

Page 6

Charge Pump for Backlight/Flash/RGB LEDs with Safety Timer (T = +25°C, unless otherwise noted.) A STROBE STARTUP WAVEFORM WITH MAIN ALREADY ON V STB V OUT I IN 1ms/div LINE-TRANSIENT RESPONSE (4V TO 3. OUT ...

Page 7

Charge Pump for Backlight/Flash/RGB LEDs PIN NAME Power-Supply Voltage Input. Connect PIN to IN. Connect a 4.7µF ceramic capacitor from PIN to 1 PIN PGND. The input voltage range is 2.7V to 5.5V. PIN is high impedance during shutdown. Analog ...

Page 8

Charge Pump for Backlight/Flash/RGB LEDs with Safety Timer INPUT 2.7V TO 5.5V PIN 4.7μF PGND REFERENCE GND AND SCK CONTROL SDA BRIGHTNESS CONTROL FSH FLASH CONTROL V DD 1.6V TO 5.5V C VDD 0.1μF ...

Page 9

Charge Pump for Backlight/Flash/RGB LEDs Detailed Description The MAX8879 charge pump operates in three modes to maintain high efficiency over a wide supply voltage range. The IC automatically selects between these three modes as described in the 1x/1.5x/2x Mode Switchover ...

Page 10

Charge Pump for Backlight/Flash/RGB LEDs with Safety Timer Table 2. Data and LED Currents DATA ...

Page 11

Charge Pump for Backlight/Flash/RGB LEDs Table 3. Control Data Byte (Hexadecimal) CONTROL BYTE (HEXADECIMAL) MAIN SUB1 SUB2 SUB3 ...

Page 12

Charge Pump for Backlight/Flash/RGB LEDs with Safety Timer Table 4. RGB Ramp Rate CONTROL BYTE RGB RAMP (HEXADECIMAL) RATE (A/ ...

Page 13

Charge Pump for Backlight/Flash/RGB LEDs by reducing the LED current above +40°C by approxi- mately 1.7%/°C. The typical derating function character- istic is shown in the Typical Operating Characteristics . The temperature derating function is enabled/disabled 2 using the I ...

Page 14

Charge Pump for Backlight/Flash/RGB LEDs with Safety Timer TOP VIEW C1N 19 C1P 20 PGND 21 MAX8879 OUT 22 C2P C2N THIN QFN 4mm x 4mm 14 ...

Page 15

Charge Pump for Backlight/Flash/RGB LEDs For the latest package outline information and land patterns www.maxim-ic.com/packages. PACKAGE TYPE 8 TQFN ______________________________________________________________________________________ with Safety Timer Package Information PACKAGE CODE T2444-4 DOCUMENT NO. 21-0139 15 ...

Page 16

Charge Pump for Backlight/Flash/RGB LEDs with Safety Timer For the latest package outline information and land patterns www.maxim-ic.com/packages. Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit ...

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