Maxim combines boost and buck converters in LED driver

Maxim MAX25601A MAX25601B MAX25601C MAX25601D

Automotive synchronous boost controller with buck LED controller optimizes 2 stage LED lighting designs

Maxim Integrated Products has released a new family of automotive ICs. The MAX25601A/B/C/D is a synchronous boost controller followed by a synchronous buck LED controller. The 4.5 V to 40 V input voltage range of the boost controller is ideal for automotive applications, and acts as a pre-boost power supply for the second-stage buck LED controller.

Maxim - MAX25601A/B/C/D

The synchronous boost is a current-mode controller that can be paralleled with another device to provide higher output power. A SYNCOUT pin provides the clock to drive the RT/SYNCIN pin of the other device, enabling two-phase 180-degree out-of-phase operation. The boost converter can be programmed with a switching frequency of 200 kHz to 2.2 MHz. Spread spectrum is included to reduce EMI. An internal digital soft-start feature is provided to enable a smooth power up of the boost output. Protection features like hiccup mode, overvoltage protection, and thermal shutdown are provided.

The synchronous buck LED controller uses Maxim's F3 Architecture, a proprietary average-current-mode control scheme to regulate the inductor current at a constant switching frequency without any control-loop compensation. Inductor current is sensed in the bottom synchronous n-channel MOSFET. The device operates over a wide 4.5 V to 65 V input range at switching frequencies as high as 1 MHz. Both analog and PWM dimming are included. LED current can be monitored on the IOUTV pin.

Both controllers have high- and low-side gate drivers with at least 1 A peak source and sink-current capability. Adaptive non-overlap control logic prevents shoot-through currents during transition. Both the boost and the buck faults are monitored on the active-low FLT pin.

Simplified Application Circuit
Simplified Application Circuit.

The MAX25601A/C is available in a 32-pin SWTQFN package and the MAX25601B/D is available in a 28-pin TSSOP package. The 32-pin package features an additional switch control that can be used in high-beam/low-beam and heads-up display applications.

Key Features

  • Integration Minimizes BOM for High-Brightness LED Driver, Saving Space and Cost
    • Wide Input-Voltage Range from 4.5 V to 40 V
    • Wide Boost-Output Range up to 65 V
    • Programmable Switching Frequency Optimizes Component Size
    • External MOSFETs Can be Sized for Appropriate Current
    • Synchronous Rectification Provides High Efficiency and Fast Transient Response
    • Average Current-Mode Control for Buck Eliminates Compensation Components
  • Wide Dimming Ratio Allows High Contrast Ratio
    • Analog Dimming and PWM Dimming
    • Analog Voltage-Controlled PWM Dimming
  • Protection Features and Wide Temperature Range Increase System Reliability
    • Short Circuit, Overvoltage, and Thermal Protection
    • –40 °C to +125 °C Operating Temperature Range


  • Automotive Exterior Lighting:
    • High-Beam/Low-Beam/ Signal/Position Lights,
    • Daytime Running Lights (DRLs),
    • Matrix Light,
    • Pixel Light,
    • Other Adaptive Front-Light Assemblies
  • Commercial, Industrial, and Architectural Lighting

JLCPCP: 2USD 2Layer 5PCBs, 5USD 4Layer 5PCBs

You may have to register before you can post comments and get full access to forum.
User Name
PCB Design Analysis Software-NextDFM One-click Design Analysis for Manufacturability Layout Engineer Free Forever