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LM3409 / LM3409HV PFET Buck Controller for High Power LED Drives
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LM3409 LM3409HV
June 12, 2009
PFET Buck Controller for High Power LED Drives
General Description
The LM3409/09HV are P-channel MosFET (PFET) controllers for step-down (buck) current regulators. They offer wide input voltage range, high-side differential current sense with low adjustable threshold voltage, fast output enable/disable function and a thermally enhanced eMSOP-10 package. These features combine to make the LM3409/09HV ideal for use as constant current sources for driving LEDs where forward currents up to 5A are easily achievable. The LM3409/09HV uses Constant Off-Time (COFT) control to regulate an accurate constant current without the need for external control loop compensation. Analog and PWM dimming are easy to implement and result in a highly linear dimming range with excellent achievable contrast ratios. Programmable UVLO, low-power shutdown, and thermal shutdown complete the feature set.
Features
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2Ω, 1A Peak MosFET Gate Drive VIN Range: 6V to 42V (LM3409) VIN Range: 6V to 75V (LM3409HV) Differential, High-side Current Sense Cycle-by-Cycle Current Limit No Control Loop Compensation Required 10,000:1 PWM Dimming Range 250:1 Analog Dimming Range Supports All-Ceramic Output Capacitors and Capacitorless Outputs ■ Low Power Shutdown ■ Thermal Shutdown Protection ■ Thermally Enhanced eMSOP-10 Package
Applications
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LED Driver Constant Current Source Automotive Lighting General Illumination Industrial Lighting
Typical Application
30085601
© 2009 National Semiconductor Corporation
300856
www.national.com
LM3409/LM3409HV
www.DataSheet4U.com
Connection Diagram
LM3409/09HV
30085602
10-Lead Exposed Pad eMSOP Package
Ordering Information
Order Number LM3409MY LM3409MYX LM3409HVMY LM3409HVMYX NSC Package Drawing MUC10A MUC10A MUC10A MUC10A Top Marking SXFB SXFB SYHB SYHB Supplied As 1000 Units on tape and reel 3500 Units on tape and reel 1000 Units on tape and reel 3500 Units on tape and reel
Pin Descriptions
Pin(s) 1 2 3 4 5 6 7 8 9 10 DAP Name UVLO IADJ EN COFF GND PGATE CSN CSP VCC VIN DAP Description Input under-voltage lockout Analog LED current adjust Logic level enable / PWM dimming Off-time programming Ground Gate drive Negative current sense Positive current sense VIN- referenced linear regulator output Input voltage Thermal pad on bottom of IC Application Information Connect to a resistor divider from VIN and GND. Turn-on threshold is 1.24V and hysteresis for turn-off is provided by a 22µA current source. Apply a voltage between 0 - 1.24V, connect a resistor to GND, or leave open to set the current sense threshold voltage. Apply a voltage >1.74V to enable device, a PWM signal to dim, or a voltage <0.5V for low power shutdown. Connect a resistor from VO, and a capacitor from GND to set the offtime. Connect to the system ground. Connect to the gate of the external PFET. Connect to the negative side of the sense.