36V High Efficiency Boost Converter with I2C Controlled 6-CH LED Driver


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The RT4537 is a high efficiency driver for white LEDs. It is suitable for single/two cell battery input to drive LED light bars which contains six strings in parallel and up to 10 WLEDs per string. The internal current sinks support a maximum of ±2% current mismatching for excellent brightness uniformity in each string of LEDs. To provide enough headroom for current sink operation, the boost controller monitors the minimum voltage of the feedback pins and regulates an optimized output voltage for power efficiency.

The RT4537 contains I2C interface for controlling the dimming mode, operating frequency and the LED current. The internal 250mΩ, 36V power switch with current-mode control provides over current protection.

The switching frequency of the RT4537 is also adjustable from 100 kHz to 1.6MHz, which allows flexibility between efficiency and component size.

The RT4537 is available in the WQFN-24L 3x3 with pitch 0.4mm package.


  • Tablet and Notebook LED Backlight
Key Spec.
Status Active
Vin (min) (V) 2.7
Vin (max) (V) 24
SW Freq (typ) (kHz) 300
Number of LEDs (max) (pcs) 11
Iout (max)/channel (mA) 25
Iq (typ) (mA) 2
Dimming Control I2C
Topology Boost + Current Source
Features Adjustable Frequency;Cycle-by-Cycle Current Limit;OCP;OVP;SCP
Package Type WQFN3x3-24
  • Wide Operating Input Voltage : 2.7V to 24V
  • High Output Voltage : Up to 36V
  • Channel Current Programmable : 3mA to 12.5mA
  • Channel Current Regulation with Accuracy ±3% and Matching ±2%
  • Dimming Controls
    ► Direct PWM up to 25kHz with Minimum 1% Duty
    ► PWM to Analog up to 2kHz with 12-Bit Resolution, Up to 4kHz with 11-Bit Resolution, Up to 8kHz with 10-Bit Resolution
    ► PWM to Mixed Up to 2kHz with 12-Bit Resolution, Up to 4kHz with 11-Bit Resolution, Up to 8kHz with 10-Bit Resolution
    ► PWM to Mixed-26KHZ up to 2kHz with 12-Bit Resolution, 4kHz with 11-Bit Resolution, Up to 8kHz with10-Bit Resolution
  • I2C Programs LED Current, Switching Frequency, Dimming Mode
  • Switching Frequency : 100kHz to 1.6 MHz
  • Embedded Memory with MTP.
  • Protections
    ► LED Strings Open Protection
    ► Current Limit Protection
    ► Programmable Over Voltage Protection
    ► Over Temperature Protection
    ► Strings Short Detection
Technical Documents
TitleLast UpdateShareDownload
Richtek Selection Guide (Oct., 2021)2021/11/23