AP880x LED Drivers with Internal Switch

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To introduce AP880X series buck DC/DC converters for driving high power LEDs

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  • Welcome to the training module on the Diodes Inc. AP880x LED Drivers with Internal Switch.
  • This training module will introduce the AP880X series buck DC/DC converters for driving high power LEDs.
  • High power LEDs are becoming more and more popular in lighting applications. They offer benefits in energy efficiency, long life and ruggedness. LEDs are low voltage devices and both safe and easy to use. However, LEDs are ‘current driven’ devices and simply applying a voltage to drive them is not a good method of control. Current control schemes are essential to maintain constant brightness. Low cost, small simple and low power multi-LED drive solutions are important for those applications to achieve maximum working life. In particular, switching regulators maximize electrical and thermal efficiency.
  • The AP880x is a step-down DC/DC converter designed to drive LEDs with a constant current. The AP880X step-down DC-DC converters require the support of only four components and operate at switching frequencies up to 600kHz, which enables the use of smaller, lower cost inductors and capacitors.  Designed to drive series-connected LEDs with a constant current, the AP880X family supports up to 13 LEDs from voltage sources between 8V and 48V. The drivers are suitable for a broad range of high-brightness, general illumination applications, including signage, architectural, emergency lighting and MR16 lamp replacement, ensuring uniform LED brightness as well as eliminate the need for ballast resistors.
  • This table shows all members in AP880x family. For an operating voltage range of 8V to 28V, the AP8800 will furnish a string of seven LEDs with a current up to 350mA, providing a cost effective match for 1W LED systems. For higher output power, the AP8801 will produce a drive current of 500mA from an operating voltage of 8V to 48V, to support up to 13 series connected LEDs. The third family member, the AP8802, will meet the requirements of higher power 3W LED systems. For an operating voltage of 8V to 48V, the driver will provide up to 13 LEDs with a constant LED current of up to 1A. All devices deliver efficiencies up to 92%, except AP8802H which provides 95% efficiency.
  • Here shows the block diagram for AP8802 LED driver. To reduce the stress on LEDs, the AP880X drivers feature an integrated soft-start function, which helps to extend LED lifetime. To increase design flexibility, the drivers also offer the choice of PWM and DC input dimming control.
  • As seen from the typical application circuit, the AP8802H only needs four components to drive series connected LEDs. The LED current is controlled by the resistor R SET , which is connected between V IN and SET pin. The inductor will determine the switching frequency, LED current accuracy and temperature. The inductor influences the LED current accuracy that the system is able to provide. Due to their low forward voltage drop and fast reverse recovery, schottky diodes provide protection for the LED drivers.
  • The LED current is controlled by the resistor R SET in typical application circuit. The LED current is decreased with the increase of the R SET value.
  • Low frequency dimming is preferred for LED dimming since the LED instantaneous driving current is constant. The color temperature of the LED is preserved at all dimming levels. However, to avoid visible flicker the PWM signal must be greater than 100Hz. High frequency dimming is preferred if the system requires low radiated emission and in/output ripple. Note that if An input voltage of 0.2V or lower at CTRL pin, the device will shut down the output at SW and put itself into a low-current standby state.
  • Thank you for taking the time to view this presentation on “ AP880x LED Drivers with Internal Switch” . If you would like to learn more or go on to purchase some of these devices, you may either click on the part list link right beside the play button on the TechCast portal, or simply call our sales hotline. For more technical information you may either visit the Diode Incorporated site, or if you would prefer to speak to someone live, please call our hotline number, or even use our ‘live chat’ online facility. You may visit element14 e-community to post your questions.
  • AP880x LED Drivers with Internal Switch

    1. 1. AP880x LED Drivers with Internal Switch <ul><li>Source: DIODES INC. </li></ul>
    2. 2. Introduction <ul><li>Purpose </li></ul><ul><ul><li>To introduce AP880X series buck DC/DC converters for driving high power LEDs </li></ul></ul><ul><li>Outline </li></ul><ul><ul><li>High power LEDs applications </li></ul></ul><ul><ul><li>AP880X LED drivers overview </li></ul></ul><ul><ul><li>Functional block diagram & Typical application circuit </li></ul></ul><ul><ul><li>LED current control & PWM dimming </li></ul></ul><ul><li>Content </li></ul><ul><ul><li>10 pages </li></ul></ul>
    3. 3. More and More High Power LEDs... <ul><li>High power LEDs are increasingly being used in lighting applications </li></ul><ul><ul><li>General illumination </li></ul></ul><ul><ul><li>Portable devices </li></ul></ul><ul><ul><li>Signage/security </li></ul></ul><ul><ul><li>Traffic </li></ul></ul><ul><ul><li>Automotive </li></ul></ul><ul><ul><li>Architectural </li></ul></ul><ul><li>They offer benefits including </li></ul><ul><ul><li>High energy efficiency </li></ul></ul><ul><ul><li>Long life </li></ul></ul><ul><ul><li>Ruggedness </li></ul></ul>
    4. 4. AP880x Step-down DC/DC Converters <ul><li>Operating voltage range from 8 to 48V </li></ul><ul><li>LED current can be up to 1A </li></ul><ul><li>Soft-start function </li></ul><ul><li>PWM and DC dimming </li></ul><ul><li>Up to 600KHz high switching frequency </li></ul><ul><li>Applications </li></ul><ul><ul><li>Commercial & Industrial lighting </li></ul></ul><ul><ul><li>Small LCD panel backlight </li></ul></ul><ul><ul><li>Architecture Detail lighting </li></ul></ul><ul><ul><li>Appliances interior lighting </li></ul></ul>
    5. 5. AP880x Offerings Part Number Input Voltage (V) Output Voltage (V) Max Output Current (A) LED Current Accuracy Max Frequency (KHz) Efficiency AP8800 8 ~ 28 28 0.35 8% 600 92% AP8801 8 ~ 48 48 0.5 8% 500 92% AP8802 8 ~ 48 48 1 8% 500 92% AP8802H 8 ~ 60 60 1 5% 500 95% AP8803 8 ~ 30 30 1 8% 700 92%
    6. 6. Functional Block Diagram
    7. 7. Typical Application Circuit
    8. 8. LED Current Control
    9. 9. PWM Dimming <ul><li>A PWM signal with a max resolution of 8-bit, can be applied to the CTRL pin to change the output current. </li></ul><ul><li>The output current can be set to above or below the nominal average value by resistor R SET . </li></ul><ul><li>Note: An input voltage of 0.2V or lower at CTRL shuts down the output at SW and puts the device into a low-current standby state. </li></ul>
    10. 10. Additional Resource <ul><li>For ordering AP880x LED Drivers, please click the part list or </li></ul><ul><li>Call our sales hotline </li></ul><ul><li>For more product information go to </li></ul><ul><ul><li>http://www.diodes.com/products/catalog/list.php?parent-id=91 </li></ul></ul><ul><li>Visit element14 to post your question </li></ul><ul><ul><li> www.element-14.com </li></ul></ul><ul><li>For additional inquires contact our technical service hotline or even use our “Live Technical Chat” online facility </li></ul>Newark Farnell

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