LM3401MMX National Semiconductor Corporation, LM3401MMX Datasheet
LM3401MMX
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LM3401MMX Summary of contents
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... A cycle by cycle current limit provides pro- tection against over current and short circuit failures. Addi- tional features include adjustable hysteresis and a CMOS compatible input pin for PWM dimming. Typical Application Circuit © 2007 National Semiconductor Corporation Features ■ Hysteretic Control for Speed and Simplicity ■ ...
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... Connection Diagram Ordering Information Part Number Package Type LM3401MM MSOP-8 LM3401MMX Pin Descriptions Pin # Pin Name 1 CS Current sense pin. Connect to the PFET drain 2 DIM Dimming input pin. When DIM is low, the HG drive is off. Can be connected to a logic level PWM signal ...
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Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN CS SNS ILIM DIM HYS Storage Temperature Electrical Characteristics apply over the junction temperature (T limits are guaranteed ...
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Typical Performance Characteristics V vs Temperature REF HYS Multiplier vs Temperature ILIM Sink Current vs Temperature www.national.com Unless otherwise specified, V HYS Current vs V 30021403 Startup Waveforms 30021406 HYS Current vs Temperature 30021408 4 = 24V 25°C. ...
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UVLO Threshold vs Temperature 30021410 Line Transient Response 30021457 350 mA Efficiency 30021458 SNS to HG Propagation Delay vs V Initial HG Voltage vs Input Voltage 700 mA and 1A Efficiency 5 IN 30021455 30021414 30021459 www.national.com ...
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Block Diagram Operational Description HYSTERETIC CONTROL The LM3401 is a step-down DC-DC controller designed to provide a constant current source for driving a high power LED string. The LM3401 uses comparator-based voltage mode hysteretic control for a simple and stable ...
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RSNS SNS LED When selecting a sense resistor, thermal de-rating must also be taken into consideration. While R sets the DC LED current, the AC peak LED cur- SNS rent will be higher than the ...
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FIGURE 4. Frequency vs Input Voltage Maximum switching frequency will typically occur around the input voltage which corresponds to 25% duty cycle. If the input voltage falls below the forward voltage of the LED string, the LM3401 will operate at ...
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SNS or DIM pins. A small capacitor for noise reduction will have little to no effect on the LED ripple current or dimming but may help solve po- tential EMI problems. HG AND PFET ...
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CS pin. Current limit is activated and latched when the voltage at the CS pin drops below the voltage at the ILIM pin. The current limit setting resistor, R3, can be calculated from the ...
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PFET turns on. The important parameters for the input ca- pacitor are the voltage rating and the RMS current rating. Follow the manufacturer’s recommended voltage de-rating. RMS current can be ...
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The SNS and HYS resistors should be placed close to their respective pins and grounded close to the GND pin. An iso- lated ground area shown as SGND in Figure 10 is recom- mended for the SNS, HYS, and GND ...
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Design Example The following design example is intended to illustrate the step-by-step design process described in the previous sec- tions. The example refers to the circuit in Figure 11, and the results are summaized in Table 1. The resulting circuit ...
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This confirms that the component selections will keep LED peak current below the maximum LED rating. Notice if a ripple reduction capacitor is chosen, the peak inductor current is still 804mA, but the LED peak current is reduced. Therefore, the ...
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This is the estimated amount of LED current variation over the input voltage range. If the minimum input voltage was below Parameter Value R1 290 mΩ R2 5.6 kΩ µH, >804 ripple ...
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Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 8-Lead MSOP Package NS Package Number MUA08A 16 ...
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Notes 17 www.national.com ...
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