MV1002SC

Application Note


Overview/Features

The MV1002SC is an LED driver IC that uses an external power supply and can consist solely of low-voltage pins. Omitting the auxiliary winding enables a single power supply configuration, and quasi-resonant operation in critical conduction mode raises efficiency and lowers noise.
In general critical conduction mode, the switching frequency increases when the dimming ratio decreases. This increases switching losses and imposes limitations on the lowest dimming ratios, disadvantageously. When the dimming ratio decreases, the MV1002SC automatically switches from critical conduction mode to discontinuous conduction mode. This prevents the switching frequency increasing, reduces switching losses, and achieves smooth and deep dimming free of flickering.

1. Allows quasi-resonant operation without auxiliary winding.
2. Quasi-resonant operation in critical conduction mode helps achieve low input change, raises efficiency, and lowers noise.
3. Off-time modulation enables deep dimming (1% or less).
4. Allows PWM dimming input and linear dimming input.
5. Allows LED open-circuit protection using auxiliary winding.
6. Features built-in thermal shutdown, UVLO, and LED short-circuit protection.
7. Allows configuration solely of low voltage pins using an external start-up circuit.


Application Note Contents

1. Overview
    1.1 Features
    1.2 Block diagram
    1.3 Pin assignment
    1.4 Pin functions
2. Explanation of basic operations
    2.1 Starting sequence
3. Component selection procedure and calculation method
    3.1 Basic circuit configuration
    3.2 Component selection
        3.2.1 MOSFET (Q1)
        3.2.2 Fly-wheel diode (D1)
        3.2.3 Current detection resistor (R1 and R2)
        3.2.4 Inductor (L1)
        3.2.5 Gate drive circuit (R4, R9, and D2)
        3.2.6 Resistors for Svin and Svout pins(R5, R6, R7 and R8)
        3.2.7 CS pin filter (R3 and C4)
        3.2.8 Vcc pin smoothing capacitor (C3)
        3.2.9 REF pin capacitor (C5)
        3.2.10 Svin pin capacitor (C9)
        3.2.11 Resonant capacitor (Cr)
        3.2.12 Input capacitor (C1) and Output capacitor (C2)
        3.2.13 Svout pin capacitor (C8)
    3.3 Winding voltage supply
        3.3.1 Configuration of a winding voltage supply
        3.3.2 Selecting the auxiliary winding (Nc)
        3.3.3 Selecting the auxiliary winding rectifier diode (D3)
        3.3.4 LED open-circuit protection using auxiliary winding
4. Cautions on pattern designing
    4.1 Cautions
    4.2 PCB pattern example
5. Dimming characteristics
    5.1 Operation in each mode
        5.1.1 [A] Frequency modulation region
        5.1.2 [B] Off-time modulation region
        5.1.3 [C] Minimum dimming region
    5.2 PWM dimming
        5.2.1 PWM dimming in 100% and minimum dimming ratio regions
        5.2.2 Combination of linear dimming and PWM dimming
        5.3 Dimming circuit
        5.3.1 Example of dimming circuit smoothing PWM signal
6. Operations in abnormal situations
    6.1 LED open-circuit
    6.2 LED short-circuit
    6.3 Abnormal heat buildup
    6.4 CS pin open-circuit
    6.5 CS-GND short-circuit
    6.6 Current detection resistor open-circuit
    6.7 Current detection resistor short-circuit
7. Standard circuit example
    7.1 Power supply specification and circuit diagram
    7.2 Power supply characteristics
    7.3 Example of operation waveform

Example Circuits


Terms and Conditions for Licensing of Application Note

Upon downloading Application Note, you will be considered as having given your consent to the content of this Agreement.
Before downloading Application Note from our website, please read thoroughly the content of the sections below, including the disclaimer, and only download Application Note by clicking the "I AGREE" button upon your agreement with the content of this Agreement. 

  1. Only those individual Customers who have agreed to this Agreement and downloaded Application Note may use Application Note under non-exclusive and non-assignable licensing terms.
    With respect to the Application Note which you downloaded, you may not sell it or lend it, or lease it out to someone else, or otherwise use it for profit, and you may not distribute, transmit (including public transmission), or otherwise provide it to someone else.
  2. The reference power supplies described in the Application Note which you downloaded (hereinafter referred to as "Licensed Application Note") are for understanding the performance of our products, and do not guarantee output, temperature, and any other characteristics, nor do they guarantee characteristics or safety specified by public agencies.
  3. Company has the copyright for the Licensed Application Note.
  4. You may not alter or adapt the entirety or any part of the Licensed Application Note, or take any other action which fails to maintain the identity of the Licensed Application Note.
  5. Use of the Licensed Application Note does not provide guarantee for, or grant license for, intellectual property rights and other rights of Company or any third party.
  6. Company does not provide any guarantee (including with regard to functional operation, merchantability, fitness for a particular purpose, accuracy of information, and guarantee of non-infringement of a third party's rights), expressly or impliedly, for the Licensed Application Note.
  7. Company is not responsible for any damage arising from the Licensed Application Note (including indirect damages, consequential damages, special damages, incidental damages, lost profits, opportunity loss, and damages due to taking leave of absence from work).
  8. The Licensed Application Note is subject to change without notice due to product improvement and the like.
  9. You shall strictly abide by applicable export control laws including the foreign exchange and foreign trade laws of each country.
  10. This Agreement takes effect upon your downloading of the Licensed Application Note.
    Company may, irrespective of the reason, terminate this Agreement at any time by posting a notice to that effect on our website.
  11. This Agreement shall be governed by the laws of Japan.

Back to Top