UCC25710

ACTIVE

LED TV backlight controller

Product details

Vin (min) (V) 11 Vin (max) (V) 18 Operating temperature range (°C) -40 to 125 Control mode Voltage Topology Half bridge, LLC Rating Catalog Features PWM dimming input, Programmable soft start, Programmable switching frequency
Vin (min) (V) 11 Vin (max) (V) 18 Operating temperature range (°C) -40 to 125 Control mode Voltage Topology Half bridge, LLC Rating Catalog Features PWM dimming input, Programmable soft start, Programmable switching frequency
SOIC (DW) 20 131.84 mm² 12.8 x 10.3
  • Closed-Loop LED String Current Control
  • PWM Dimming Input
  • Adjustable FMIN (3% accuracy), and FMAX (7.5% Accuracy)
  • LLC and Series LED Switch Control for Dimming
  • Programmable Dimming LLC ON/OFF Ramp for Elimination of Audible Noise
  • Closed-Loop Current Control at Low Dimming Duty Cycles
  • Programmable Soft Start
  • Accurate VREF for Tight Output Regulation
  • Overvoltage, Undervoltage and Input Overcurrent Protection With Auto-Restart Response
  • Second Overcurrent Threshold With Latch-Off Response
  • 400-mA/-800-mA Gate Drive Current
  • Low Start-Up and Operating Currents
  • Lead (Pb)-Free, 20-Pin, SOIC Package
  • Closed-Loop LED String Current Control
  • PWM Dimming Input
  • Adjustable FMIN (3% accuracy), and FMAX (7.5% Accuracy)
  • LLC and Series LED Switch Control for Dimming
  • Programmable Dimming LLC ON/OFF Ramp for Elimination of Audible Noise
  • Closed-Loop Current Control at Low Dimming Duty Cycles
  • Programmable Soft Start
  • Accurate VREF for Tight Output Regulation
  • Overvoltage, Undervoltage and Input Overcurrent Protection With Auto-Restart Response
  • Second Overcurrent Threshold With Latch-Off Response
  • 400-mA/-800-mA Gate Drive Current
  • Low Start-Up and Operating Currents
  • Lead (Pb)-Free, 20-Pin, SOIC Package

The UCC25710 device is an LLC half-bridge controller for accurate control of multi-string LED backlight applications. It is optimized for multi-transformer, multi-string LED architectures. Superior LED current matching in multiple strings can be achieved with this controller and architecture. Compared to existing LED backlight solutions, the multi-transformer architecture provides the highest overall efficiency from AC input to LED load.

The LLC controller function includes a Voltage Controlled Oscillator (VCO) with programmable FMIN and FMAX, half-bridge gate drivers with a fixed dead time of 500 ns and a GM current amplifier. The LLC power delivery is modulated by the controller’s VCO frequency. The VCO has an accurate and programmable frequency range. At very low power levels the VCO frequency goes from FMAX to zero to maximize efficiency at low LED currents.

The LED current loop reference is set by a divider off the VREF 5-V output. The reference can be varied over a 0.5-V to 2.6-V range, allowing analog dimming to be combined with PWM dimming.

PWM dimming is used to control an external LED series switch and also to gate on and off the LLC power stage. The LEDSW output along with a simple drive circuit is used to switch on and off the LED string current. This output responds directly to the input signal at the dimming input, DIM. The LLC is also ramped on and off with the dimming PWM input. The on and off LLC dimming edges are ramped at programmable slew rates to control audible noise. The dimming function includes duty-cycle compensation to allow optimization of overall efficiency and dimming linearity over a maximum range.

The control voltage to the VCO is set by ICOMP (current amplifier output) during LED ON-times. During start-up the soft-start pin, SS, controls the VCO response until it exceeds ICOMP. During dimming the rise and fall rates of the VCO input are controlled by the voltage at the dimming slew rate, DSR, pin while the pedestal of VCO control level continues to be controlled by ICOMP. The current amplifier output is connected to ICOMP only during the commanded dimming LED ON-time. The LLC on-time is extended beyond the LED current ON-time at low dimming duty-cycles to maintain closed-loop control of the LED current.

Protection thresholds for LED string overvoltage and undervoltage conditions are set with external resistive dividers and accurate internal thresholds. Input current to the converter is monitored with both a restart and latchoff response depending on the overcurrent level. The controller also includes thermal shutdown protection.

The auto restart response to any fault includes a 10-ms reset period followed by a soft start. In the case of a severe input overcurrent, restart is disabled until the input supply is cycled through its UVLO threshold.

The UCC25710 device is an LLC half-bridge controller for accurate control of multi-string LED backlight applications. It is optimized for multi-transformer, multi-string LED architectures. Superior LED current matching in multiple strings can be achieved with this controller and architecture. Compared to existing LED backlight solutions, the multi-transformer architecture provides the highest overall efficiency from AC input to LED load.

The LLC controller function includes a Voltage Controlled Oscillator (VCO) with programmable FMIN and FMAX, half-bridge gate drivers with a fixed dead time of 500 ns and a GM current amplifier. The LLC power delivery is modulated by the controller’s VCO frequency. The VCO has an accurate and programmable frequency range. At very low power levels the VCO frequency goes from FMAX to zero to maximize efficiency at low LED currents.

The LED current loop reference is set by a divider off the VREF 5-V output. The reference can be varied over a 0.5-V to 2.6-V range, allowing analog dimming to be combined with PWM dimming.

PWM dimming is used to control an external LED series switch and also to gate on and off the LLC power stage. The LEDSW output along with a simple drive circuit is used to switch on and off the LED string current. This output responds directly to the input signal at the dimming input, DIM. The LLC is also ramped on and off with the dimming PWM input. The on and off LLC dimming edges are ramped at programmable slew rates to control audible noise. The dimming function includes duty-cycle compensation to allow optimization of overall efficiency and dimming linearity over a maximum range.

The control voltage to the VCO is set by ICOMP (current amplifier output) during LED ON-times. During start-up the soft-start pin, SS, controls the VCO response until it exceeds ICOMP. During dimming the rise and fall rates of the VCO input are controlled by the voltage at the dimming slew rate, DSR, pin while the pedestal of VCO control level continues to be controlled by ICOMP. The current amplifier output is connected to ICOMP only during the commanded dimming LED ON-time. The LLC on-time is extended beyond the LED current ON-time at low dimming duty-cycles to maintain closed-loop control of the LED current.

Protection thresholds for LED string overvoltage and undervoltage conditions are set with external resistive dividers and accurate internal thresholds. Input current to the converter is monitored with both a restart and latchoff response depending on the overcurrent level. The controller also includes thermal shutdown protection.

The auto restart response to any fault includes a 10-ms reset period followed by a soft start. In the case of a severe input overcurrent, restart is disabled until the input supply is cycled through its UVLO threshold.

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Technical documentation

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Type Title Date
* Data sheet UCC25710 LLC Half-Bridge Controller For Multi-String LED Lighting datasheet (Rev. B) PDF | HTML 15 Feb 2016
Selection guide Power Management Guide 2018 (Rev. R) 25 Jun 2018
Application note A New Off-line LED Lighting Driver Solution with multi-transformer LLC Control (Rev. A) 13 Sep 2011
Application note UCC25710 98-W LLC Resonant Half-Bridge 4-String LED Driver Design 17 May 2011
EVM User's guide Using the UCC25710EVM-654 (Rev. A) 22 Mar 2011

Design & development

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Supported products & hardware

Supported products & hardware

Products
AC/DC & DC/DC controllers (external FET)
UCC25710 LED TV backlight controller
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SOIC (DW) 20 Ultra Librarian

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