Maxim > Products > Power and Battery Management > MAX1848

MAX1848

White LED Step-Up Converter in SOT23

Current Regulated Step-Up Converter Powers White LEDs with Uniform Brightness

Overview

Technical Documents

Ordering Info

Status

Active: In Production.

Description

The MAX1848 drives white LEDs with a constant current to provide backlight in cell phones, PDAs, and other hand-held devices. The step-up converter topology allows series connection of the white LEDs so that the LED currents are identical for uniform brightness. This configuration eliminates the need for ballast resistors and expensive factory calibration. Other benefits include greater simplicity, lower cost, higher efficiency, and greater reliability.

This step-up PWM converter includes an internal, high-voltage, low R_DSON N-channel MOSFET switch for high efficiency and maximum battery life. A single analog voltage Dual Mode™ input provides a simple means of brightness adjustment and on/off control. Fast 1.2MHz current-mode PWM control allows for small input and output capacitors and a small inductor while minimizing ripple on the input supply/battery. Programmable soft-start eliminates inrush current during startup.

The MAX1848 is available in space-saving 8-pin thin QFN (3mm x 3mm) and 8-pin SOT23 packages.

Data Sheet

Download	Rev 2	(PDF, 284kB)
E-Mail

An evaluation kit is available: MAX1848EVKIT

Key Features

Constant Current Regulation for Uniform Illumination
High 87% Efficiency
Analog or Logic Control of LED Intensity
0.8W Output Power with Internal High-Voltage MOSFET Switch
Small, Low-Profile External Components
2.6V to 5.5V Input Range
13V Maximum Output with Overvoltage Protection
Optimized for Low Input Ripple
Programmable Soft-Start
0.3µA Shutdown Current
Small 8-pin Thin QFN (3mm x 3mm) and 8-Pin SOT23 Packages

Applications/Uses

Cell Phones/Smartphones
e-Books and Subnotebooks
PDAs, Palmtops, and Wireless Handhelds
White LED Display Backlighting

Key Specifications:

White LED Drivers

Part Number

Topology

LEDs

Config.

Dimming Control

V_{CURR_SENSE}
(mV)

P_OUT
(W)

I_LED
(mA)

V_IN
(V)

I_CC
(mA)

V_OUT
(V)

Oper. Freq.
(kHz)

Package/Pins

Budgetary Price

max num. of

max

min

max

See Notes

MAX1848

Inductor Based

Series

Analog

0.8

2.6

5.5

1200

SOT/8

TDFN-EP/8

$1.32 @1k

See All White LED Drivers (47)

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Diagram

Typical Application Circuit

Application Notes

Application Note 940		Feedback Circuit Enhances Efficiency of Boost-Converter Current Source
Application Note 1037		Charge-Pump and Step-Up DC-DC Converter Solutions for Powering White LEDs in Series or Parallel Connections
Application Note 1736		Powering Four White LEDs with High Efficiency Using the MAX1848
Application Note 1750		Powering Six White LEDs with High Efficiency Using the MAX1848
Reference Design 1804		Driving LEDs in Battery-Operated Applications: Controlling Brightness Power Efficiently
Application Note 3070		Standard and White LED Basics and Operation
Application Note 3256		Why Drive White LEDs with Constant Current?
Application Note 3444		Light Is On When Power Is Out
Application Note 3624		Driving White LEDs in Clamshell Phones
Tutorial 4686		Important Design Considerations for Heart-Rate and Fitness Monitors
Tutorial 4689		Blood Pressure Monitor Design Considerations
Tutorial 4690		Important Design Considerations for Digital Thermometers

Reliability Reports

Reliability Report:	MAX1848.pdf
Show FIT data for:

Software/Models

none

Ordering Information

Filters:

Part Number:

Package:

Temperature:

Tape and Reel

Sample

Part Number	Free Sample	Buy	Status	Package: TYPE PINS FOOTPRINT DRAWING CODE/VAR *	Temp	RoHS/Lead-Free? Materials Analysis
MAX1848EKA-T			Active	SOT;8 pin;9 mm² Outline Drawing:21-0078 (PDF) Land Pattern: 90-0176 (PDF) Use pkgcode/variation: K8F-4*	-40°C to +85°C	See data sheet
MAX1848ETA+			Active	TDFN-EP;8 pin;9.6 mm² Outline Drawing:21-0137 (PDF) Land Pattern: 90-0059 (PDF) Use pkgcode/variation: T833+2*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
MAX1848ETA+T			Active	TDFN-EP;8 pin;9.6 mm² Outline Drawing:21-0137 (PDF) Land Pattern: 90-0059 (PDF) Use pkgcode/variation: T833+2*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
MAX1848ETA-T			Active	TDFN-EP;8 pin;9.6 mm² Outline Drawing:21-0137 (PDF) Land Pattern: 90-0059 (PDF) Use pkgcode/variation: T833-2*	-40°C to +85°C	RoHS/Lead-Free: No Materials Analysis

Notes:

Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt; -D = drypack; -U/+U on DS parts = cut tape. More: See Full Data Sheet or Maxim Product Naming Conventions.
* Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.

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Evaluation Kits

MAX1848EVKIT

Evaluation Kit for the MAX1848

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