Rainbow-electronics MAX8848Z Manual de usuario descargar pdf (Pagina 1)

_______________________________________________________________ Maxim Integrated Products 1

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.

High-Performance Negative Charge Pump

for 7 White LEDs in 3mm x 3mm Thin QFN

MAX8848Y/MAX8848Z

19-5233; Rev 0; 4/10

Typical Operating Circuit

General Description

The MAX8848Y/MAX8848Z negative charge pumps

drive up to 7 white LEDs with regulated constant current

for display backlight applications. By utilizing an invert-

ing charge pump and extremely low-dropout adaptive

current regulators, these ICs achieve very high efficiency

over the full 1-cell Li+ battery voltage range even with

large LED forward voltage mismatch. The 1MHz fixed-

frequency switching allows for tiny external components.

The regulation scheme is optimized to ensure low EMI

and low input ripple. The MAX8848Y/MAX8848Z include

thermal shutdown, open- and short-circuit protection.

The MAX8848Y/MAX8848Z support independent LED

on/off and dimming control. The MAX8848Y dimming

ranges are pseudo-logarithmic from 24mA to 0.1mA and

off in 32 steps. All devices include a temperature derat-

ing function to safely allow bright 24mA full-scale output

current while automatically reducing current gradually

to protect LEDs at high ambient temperatures above

+60NC.

The MAX8848Y/MAX8848Z are available in 16-pin,

3mm x 3mm thin QFN packages.

Applications

White LED Backlighting

Cellular Phones

PDAs, Digital Cameras, and Camcorders

Features

S Negative 1x/1.5x Charge Pump

S Adaptive Current Regulators

S Independent Voltage Supply for Each LED

S 24mA to 0.1mA Serial-Pulse Dimming (MAX8848Y)

S 24mA to 0mA PWM Dimming (MAX8848Z)

S 2% (max) LED Current Accuracy, 1% (typ) Matching

S Low 120µA Quiescent Current

S Low 0.4µA Shutdown Current

S Inrush Current Limit

S Temperature Derating Function

S 16-Pin, 3mm x 3mm Thin QFN Packages

Ordering Information

Note: All devices are specified over the -40°C to +85°C

extended temperature range.

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

*EP = Exposed pad.

EVALUATION KIT

AVAILABLE

1µF

INPUT

2.7V TO 5.5V

NEG

LED1

LED2

LED3

LED4

LED5

LED6

LED7

C1P C1N C2P C2N

GND

ENA

(ENB)

<CPWM>

LED ENABLE

AND

DIMMING

CONTROL

1µF

0.22µF

NOTE: ( ) FOR MAX8848Y, < > FOR MAX8848Z

1µF

MAX8848Y

MAX8848Z

PART DIMMING PIN-PACKAGE

TOP

MARK

MAX8848YETE+T

Serial pulse/

PWM

16 Thin QFN-EP* AHQ

MAX8848ZETE+T PWM 16 Thin QFN-EP* AHP

1 2 3 4 5 6 ... 13 14

MAX8848Y/MAX8848Z 1

Indice de contenidos

Pagina 1 - MAX8848Y/MAX8848Z

_______________________________________________________________ Maxim Integrated Products 1For pricing, delivery, and ordering information, pleas

Pagina 2

High-Performance Negative Charge Pump for 7 White LEDs in 3mm x 3mm Thin QFNMAX8848Y/MAX8848Z10 _________________________________________________

Pagina 3