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Richtek
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The RT4540A is a high-efficiency driver for white LEDs. It is suitable for single/two cell battery input to drive LED light bars which contain six strings in parallel. 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 RT4540A 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 overcurrent protection.The switching frequency of the RT4540A is also adjustable from 100kHz to 1.6MHz, which allows flexibility between efficiency and component size. The RT4540A is available in a WQFN3x3-24 with pitch 0.4mm package. The recommended junction temperature range is −40°C to 150°C, and the ambient temperature range is −40°C to 125°C.

應用

  • Tablet and Notebook LED Backlights
主要規格
RT4540A
Status Active
Vin (min) (V) 2.7
Vin (max) (V) 24
Vout (max) (V) 36
LED Channels 6
Topology Boost
SW Freq (typ) (kHz) 300
Vcs (typ) (mV) 500
Dimming Control PWM;PWM-to-Analog
Features Adjustable Frequency;Backlight;Current Mode Control;Cycle-by-Cycle Current Limit;Enable Input;Fast Transient Response;I2C;Internal Compensation;OCP;OVP;SCP;Stable with Ceramic Capacitor
Package Type WQFN3x3-24
Outline Dimension, Footprint, Drawing Download
關鍵特性
  • Wide Operating Input Voltage: 2.7V to 24V
  • High Output Voltage: up to 36V
  • Channel Current Programmable: 6mA to 25mA
  • 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 1.6MHz
  • Embedded Memory with MTP
  • Protections
    - LED Strings Open Protection
    - Overcurrent Protection
    - Programmable Overvoltage Protection
    - Over-Temperature Protection
    - Strings Short Detection
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