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Driving LEDs with a Boost Regulator

Driving LEDs with a Boost Regulator



Introduction of the MCP1650/51/52/53 boost controllers and their applications for driving LEDs

Introduction of the MCP1650/51/52/53 boost controllers and their applications for driving LEDs



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    Driving LEDs with a Boost Regulator Driving LEDs with a Boost Regulator Presentation Transcript

    • Driving LEDs with a Boost Regulator
      • Source: Microchip Technology
    • Introduction
      • Purpose
        • This training module introduces the MCP1650/51/52/53 boost controllers and their applications for driving LEDs.
      • Outline
        • Boost regulator basics
        • Overview of MCP1650/51/52/53 devices
        • Key features
        • LED driver applications
      • Content
        • 15 pages
    • Boost Regulator Basics
      • The output voltage of the boost converter must be equal to or greater than the input voltage.
      • A boost regulator is useful for driving a chain of LEDs connected in series.
      Boost Reg
    • MCP165x Boost Controllers
      • Output Power Capability Over 5 Watts.
      • 560/440 Output Current (mA).
      • Output Voltage Capability From 3.3V to Over 100V.
      • 750 kHz Gated Oscillator Switching Frequency.
      • Adaptable Duty Cycle for Battery or Wide-Input, Voltage-Range Applications.
      • Input Voltage Range: 2.0V to 5.5V.
      • Capable of SEPIC® and Fly back Topologies.
      • Shutdown Control with IQ < 0.1 µA (Typical).
      • Low Operating Quiescent Current: IQ = 120 µA.
      • Voltage Feedback Tolerance (0.6%, Typical).
      • Popular MSOP-8 Package.
      • Peak Current Limit Feature.
      • Two Under voltage Lockout (UVLO) Options: 2.0V or 2.55V.
      • Operating Temperature Range: -40°C to +125°C.
    • Block Diagram
    • Pin Descriptions
      • External Gate Drive (EXT)
        • The output pin drives the external N-channel MOSFET on and off during boost operation.
      • Current Sense (CS)
        • Input peak current is sensed on CS through the external current sense resistor.
      • Feedback Input (FB)
        • Connect output voltage of boost converter through external resistor divider to the FB pin for voltage regulation.
      • Shutdown Input (SHDN)
        • The SHDN input is used to turn the boost converter on and off.
    • PIN Descriptions cont’d Low Battery Input (LBI) LBI is the input pin for the low battery comparator. Low Battery Output (LBO) LBO is an active-low, open-drain output capable of sinking 10 mA when the LBI pin is below the threshold voltage. Power Good (PG) PG is an active-high, open-drain output capable of sinking 10 mA when the FB input pin is 15% below its typical value or more than 15% above its typical value, indicating that the output voltage is out of regulation.
    • Low Power Detection (MCP1651 /53)
      • The Low-Battery Detect feature can be used to determine when the LBI input voltage has fallen below a predetermined threshold.
      • The low-battery detect feature compares the low battery input (LBI) pin to the internal 1.22V reference.
        • If the LBI input is below the LBI threshold voltage, the low battery output (LBO) pin will sink current up to 10 mA.
        • If the LBI input voltage is above the LBI threshold, the LBO output pin will be open or high impedance.
      Low Battery Detection (LBI)
    • Power Good Indication (MCP1652 / 53)
      • The Power Good Output feature monitors the divided-down voltage feedback into the FB pin.
      • The power good feature compares the voltage on FB pin to the internal reference (±15%).
        • If the FB pin is more than 15% above or below the power good threshold, the PG output will sink current.
        • If the output of the regulator is within ±15% of the output voltage, the PG pin will be open or high-impedance
      V REF VFB Power Good Indication
    • Other Functionalities
      • Soft-Start Operation
        • When power is first applied to the MCP1650/51/52/53, the internal reference initialization is controlled to slow down the start-up of the boost output voltage.
      • PWM Latch
        • The gated oscillator is self-latched to prevent double and sporadic pulsing.
      • Overcurrent Limit
        • The Current Sense (CS) input pin is used to sense the peak input current of the boost converter.
        • This can be used to limit how high the peak inductor current can reach.
    • Typical Non-Bootstrap Application Circuit (MCP1650/51/52/53)
      • Non-bootstrap applications are typically used when the output voltage is boosted to a voltage that is higher than the rated voltage of the Device.
      • In this application, output voltages of over 100V can be generated.
      3.3V to 12V 100mA Boost Converter
    • Battery Operated Boost LED Driver
      • The MCP1650 Boost Controller is capable of generating output voltages of over 100V.
      • The MCP1650 is configured in the conventional boost topology.
      R SENSE
    • High Efficiency LED Smart Driver
      • The MCP1702 directly connected to the 12 volt source creates a 5 volt bias supply.
      • The MCP1652 powered the LEDs, minimizing the current requirements for the 5V power system.
      • A PIC10F202 adds intelligence to the circuit.
    • Driving LEDs with a SEPIC Regulator
      • The SEPIC converter can buck or boost as the input voltage changes.
      • The circuit topology provides inherent short-circuit protection due to the use of a coupling capacitor.
    • Additional Resource
      • For ordering the MCP1650/51/52/53, please click the part list or
      • Call our sales hotline
      • For additional inquires contact our technical service hotline
      • For more product information go to http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en500061