MAX1848: White LED Step-Up Converter in SOT23 Data Sheet (Rev. 2)9/15/2005277K
Features and Benefits
- 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
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 RDSON 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.
- Cell Phones/Smartphones
- e-Books and Subnotebooks
- PDAs, Palmtops, and Wireless Handhelds
- White LED Display Backlighting
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
The MAX1848 evaluation kit (EV kit) is a fully assembled and tested circuit board that contains a step-up switching-regulator current source powering three series-connected white LEDs. The circuit provides programmable LED current. The EV kit can be powered from a 2.6VDC to 5.5VDC source.
The MAX1848 features programmable soft-start and LED brightness control. The MAX1848 EV kit demonstrates matching LED brightness with high converter efficiency (87%) to maximize battery life. Operation at 1.2MHz allows the use of tiny surface-mount components.
- Cell Phones
- Consumer Audio
- Digital Still Cameras
- LCD Displays and Panels
- Palmtops, Handy Terminals
- Pen Entry Palmtops, PDAs and Organizers
- Point-of-Sale Terminals
Features & Benefits
Documentation & Resources
MAX1848 Reliability Data1/12/2023163K
Driving LEDs in Battery-Operated Applications: Controlling Brightness Power Efficiently3/3/2023
Important Design Considerations for Heart-Rate and Fitness Monitors5/10/2010
Blood Pressure Monitor Design Considerations5/10/2010
Important Design Considerations for Digital Thermometers5/10/2010
Light Is On When Power Is Out2/16/2005
Why Drive White LEDs with Constant Current?8/24/2004
Guide to LED Circuit Designs and LED Basics & Operation6/15/2004
Powering Six White LEDs with High Efficiency Using the MAX18489/30/2002
Charge-Pump and Step-Up DC-DC Converter Solutions for Powering White LEDs in Series or Parallel Connections4/23/2002
Feedback Circuit Enhances Efficiency of Boost-Converter Current Source1/18/2002
MAX1848 Companion Parts
Recommended Related Parts
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(*)The 1Ku list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
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