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Automotive 6-Channel Backlight Driver with Boost/SEPIC Controller and I2C Interface

6-Channel 120mA LED Driver Provides Full Diagnostics and Hybrid Dimming thru I2C

Product Details

The MAX20446 is a 6-channel backlight driver with boost controller for automotive displays. The integrated current outputs can sink up to 130mA LED current each. The device accepts a wide 4.5V to 36V input voltage range and withstands direct automotive load-dump events.

The internal current-mode switching DC-DC controller supports boost or SEPIC topologies and operates in the frequency range 400kHz to 2.2MHz. Integrated spread spectrum helps reduce EMI. An adaptive output-voltage control scheme minimizes power dissipation in the LED current-sink paths.

The device features I2C-controlled pulse-width modulation (PWM) dimming and hybrid dimming. In either case the minimum pulse width is 500ns. Phase-shifted dimming of the strings is incorporated for lower EMI.

Comprehensive diagnostic information is also available via the I2C interface.

The MAX20446 is available in a TQFN package and operates in the -40°C to 125°C temperature range.

Design Solution: Overcome the Design Challenges of New Automotive Display Backlights ›

Key Features

  • Wide-Voltage-Range Operation
    • Operates Down to 4V Supply After Startup
    • Survives Load Dump Up to 52V
  • High Integration
    • Complete 6-Channel Solution Including Boost Controller
    • I2C Control for Minimum Parts Count
  • Robust and Low EMI
    • Spread-Spectrum Oscillator
    • Phase Shifting
    • 400kHz to 2.2MHz Switching-Frequency Range
    • Fail-Safe Operation Mode Using the FSEN Pin
  • Versatile Dimming Scheme Allows Hybrid or PWM-Only Dimming Using DIM Input or I2C
    • Dimming Ratio > 10000:1 Using Hybrid Dimming
    • 10000:1 Dimming Ratio at 200Hz using PWM Dimming
  • Complete Diagnostics
    • LED Open/Short Detection and Protection
    • Boost Output Undervoltage and Overvoltage
    • Boost Voltage
    • Individual String LED Current
    • Thermal Shutdown
  • Compact (4mm x 4mm) 24-Pin TQFN Package

Applications/Uses

  • Central Information Displays
  • Infotainment Displays
  • Instrument Clusters
Parametric specs for LED Drivers
VIN (V) (min) 4.5
VIN (V) (max) 36
Max. No. of LEDs 44
# LED Channels 6
Regulation Topology Inductor Based
LED Configuration Series-Parallel
ILED per Channel (A) (max) 0.13
PWM Dimming Freq. (kHz) (max) 200
Dimming Ratio (max) 20000
Dimming Control Analog
I2C Serial
PWM
POUT (W) 32
ICC (mA) (max) 10
LED String Volt. (V) (max) 52
Switching Frequency (kHz) 500
700
750
1000
1200
1500
2000
2100
2200
Package/Pins TQFN-CU/24
Budgetary
Price (See Notes)
$2.82 @1k
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Simplified Block Diagram

MAX20446: Typical Application Circuit MAX20446: Typical Application Circuit Zoom icon

Technical Docs

Design & Development

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Description

The MAX20446 evaluation kit (EV kit) demonstrates the MAX20446 integrated 6-channel high-brightness (HB) LED backlight driver with boost/SEPIC controller and I2C interface for automotive displays.

The EV kit operates from a DC supply voltage between 4.5V and 36V and the switching frequency can be set either at 2.2MHz or at 400kHz. The EV kit operates in I2C mode only. Spread-spectrum mode (SSM) is enabled by default for EMI improvement, but can be disabled by acting on a register bit. The EV kit demonstrates phase-shifted pulse-width modulation (PWM) dimming. Dimming can be performed externally using a PWM signal applied to the DIM PCB pad, or internally by programming the desired dimming frequency and individual duty cycle through I2C. The hybrid dimming feature can be enabled through a register bit to reduce EMI. The EV kit also demonstrates short-LED, open-LED, boost output undervoltage, as well as overvoltage- and overtemperature-fault protection.

For operation at switching frequencies other than 2.2MHz or 400kHz, the external components should be chosen according to the calculations in the MAX20446 IC data sheet.

The EV kit provides an I2C interface that can operate in conjunction with the Maxim command module (MINIQUSB+) or a third-party I2C master. The EV kit also includes, Windows®-compatible software that provides a simple graphical user interface (GUI) for exercising the features of the IC.

View Details

Features

  • Demonstrates Robustness of the MAX20446
  • Wide 4.5V to 36V Input Operating Range (Up to 52V Load Dump)
  • Powers HB LEDs (Up to Six Strings) for Medium-to- Large-Sized LCD Displays in Automotive and Display Backlight Applications
  • 400kHz to 2.2MHz Resistor-Programmable Switching Frequency with Spread-Spectrum Option
  • Phase-Shift Dimming Option
  • Demonstrates Cycle-by-Cycle Current Limit and Thermal-Shutdown Features
  • Demonstrates Wide Dimming Ratio
  • Demonstrates Fail-Safe Operation
  • I2C Programmability
  • Dedicated GUI
  • Proven PCB Layout and Thermal Design
  • Fully Assembled and Tested

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Parameters

Parametric specs for LED Drivers
VIN (V) (min) 4.5
VIN (V) (max) 36
Max. No. of LEDs 44
# LED Channels 6
Regulation Topology Inductor Based
LED Configuration Series-Parallel
ILED per Channel (A) (max) 0.13
PWM Dimming Freq. (kHz) (max) 200
Dimming Ratio (max) 20000
Dimming Control Analog
I2C Serial
PWM
POUT (W) 32
ICC (mA) (max) 10
LED String Volt. (V) (max) 52
Switching Frequency (kHz) 500
700
750
1000
1200
1500
2000
2100
2200
Package/Pins TQFN-CU/24
Budgetary
Price (See Notes)
$2.82 @1k

Key Features

  • Wide-Voltage-Range Operation
    • Operates Down to 4V Supply After Startup
    • Survives Load Dump Up to 52V
  • High Integration
    • Complete 6-Channel Solution Including Boost Controller
    • I2C Control for Minimum Parts Count
  • Robust and Low EMI
    • Spread-Spectrum Oscillator
    • Phase Shifting
    • 400kHz to 2.2MHz Switching-Frequency Range
    • Fail-Safe Operation Mode Using the FSEN Pin
  • Versatile Dimming Scheme Allows Hybrid or PWM-Only Dimming Using DIM Input or I2C
    • Dimming Ratio > 10000:1 Using Hybrid Dimming
    • 10000:1 Dimming Ratio at 200Hz using PWM Dimming
  • Complete Diagnostics
    • LED Open/Short Detection and Protection
    • Boost Output Undervoltage and Overvoltage
    • Boost Voltage
    • Individual String LED Current
    • Thermal Shutdown
  • Compact (4mm x 4mm) 24-Pin TQFN Package

Applications/Uses

  • Central Information Displays
  • Infotainment Displays
  • Instrument Clusters

Description

The MAX20446 is a 6-channel backlight driver with boost controller for automotive displays. The integrated current outputs can sink up to 130mA LED current each. The device accepts a wide 4.5V to 36V input voltage range and withstands direct automotive load-dump events.

The internal current-mode switching DC-DC controller supports boost or SEPIC topologies and operates in the frequency range 400kHz to 2.2MHz. Integrated spread spectrum helps reduce EMI. An adaptive output-voltage control scheme minimizes power dissipation in the LED current-sink paths.

The device features I2C-controlled pulse-width modulation (PWM) dimming and hybrid dimming. In either case the minimum pulse width is 500ns. Phase-shifted dimming of the strings is incorporated for lower EMI.

Comprehensive diagnostic information is also available via the I2C interface.

The MAX20446 is available in a TQFN package and operates in the -40°C to 125°C temperature range.

Design Solution: Overcome the Design Challenges of New Automotive Display Backlights ›

Simplified Block Diagram

MAX20446: Typical Application Circuit MAX20446: Typical Application Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal