MAX1895, MAX1995 High-Efficiency, Wide Brightness Range, CCFL Backlight Controllers

Status

Active: In Production.

Description

FULL DATA SHEET (PDF, 1.2MB)
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The MAX1895/MAX1995 integrated controllers are optimized to drive cold-cathode fluorescent lamps (CCFL) using a synchronized full-bridge inverter architecture. Synchronized drive provides near sinusoidal waveforms over the entire input range to maximize the life of CCFLs. The controllers also operate over a wide input voltage range with high efficiency and broad dimming range.

The MAX1895/MAX1995 include safety features that limit the transformer secondary voltage and protect against single-point fault conditions including lamp-out and short-circuit faults.

The MAX1895/MAX1995 regulate the CCFL brightness in three ways: linearly controlling the lamp current, digital pulse-width modulating (DPWM) the lamp current, or using both methods simultaneously to achieve the widest dimming range (>30:1). CCFL brightness can be controlled with either an analog voltage (both MAX1895 and MAX1995) or a two-wire SMBus™ compatible interface (MAX1895 only).

The MAX1895/MAX1995 directly drive the four external N-channel power MOSFETs of the full-bridge inverter. An internal 5.3V linear regulator powers the MOSFET drivers, the synchronizable DPWM oscillator, and most of the internal circuitry. The MAX1895/MAX1995 are available in the space-saving 28-pin thin QFN package and operate over the -40��C to +85��C temperature range.

An evaluation kit is available: MAX1895EVSYS, MAX1995EVSYS

Key Features		Applications/Uses
Synchronized-to-Resonant Frequency Good Crest Factor for Longer Lamp Life Ensures Maximum Strike Capability High Power to Light Efficiency Wide Dimming Range (3 Methods) Lamp Current Adjust: >3 to 1 Digital PWM (DPWM): >10 to 1 Combined: >30 to 1 Feed-Forward for Fast Response to Step Change of Input Voltage Wide Input Voltage Range (4.6V to 28V) Transformer Secondary Voltage Limiting to Reduce Transformer Stress Lamp-Out Protection with 2s Timeout Short-Circuit and Other Single-Point Fault Protections Synchronizable DPWM Frequency Dual-Mode Brightness Control Interface SMBus Serial Interface (MAX1895 Only) Analog Interface (Both Devices) High-Accuracy Analog Interface Separate 100% Brightness Voltage Reference Pin (CRFSDA) Separate Minimum Lamp-Current Set-Point Pin (MINDAC) Small Footprint 28-Pin Thin QFN (5mm x 5mm) Package		Car-Navigation Displays LCD Monitors Notebook Computers Point-of-Sale Terminals Portable Display Electronics

Key Specifications: CCFL Controllers

Part Number

Features

V_IN
(V)

Topology

Channels

Dimming Interface

Freq.

EV Kit

Package/Pins

Smallest Available Pckg.
(mm²)

Oper. Temp.
(��C)

Price

min

max

max w/pins

See Notes

MAX1895

All N-FET Drive

Lamp Fault Output

Status Registers

Synchonizable

4.6

Full-Bridge

Analog

DPWM

I2C

SMBus

Fixed PWM

Yes

See Data Sheet/

-40 to +85

MAX1995

All N-FET Drive

Synchonizable

Analog

DPWM

QFN/28

See All CCFL Controllers (17)

Diagram

Functional Diagram

source��ShenZhen henlito electronic co.,ltd.

web:www.henlito.com