LM3478 MDC National Semiconductor, LM3478 MDC Datasheet
LM3478 MDC
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LM3478 MDC Summary of contents
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... Adjustable clock frequency ■ ±2.5% (over temperature) internal reference ■ 10µA shutdown current (over temperature) Typical Application Circuit © 2009 National Semiconductor Corporation LM3478/LM3478Q Features ■ LM3478Q is AEC-Q100 qualified and manufactured on an Automotive Grade Flow ■ 8-lead Mini-SO8 (MSOP-8) package ■ ...
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Connection Diagram Package Marking and Ordering Information Order Number Package Type LM3478MM MSOP-8 LM3478MMX LM3478QMM MSOP-8 LM3478QMMX * Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including defect detection methodologies. Reliability qualification is compliant ...
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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. Input Voltage FB Pin Voltage FA/SD Pin Voltage Peak Driver Output Current (<10µs) Power Dissipation Storage Temperature Range Junction Temperature ESD Susceptibilty Human Body Model (Note 2) ...
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Symbol Parameter V Internal Compensation Ramp SL Voltage V Output Over-voltage OVP Protection (with respect to feedback voltage) (Note 8) V Output Over-Voltage OVP(HYS) Protection Hysteresis(Note 8) Gm Error Ampifier Transconductance A Error Amplifier Voltage Gain VOL I Error Amplifier ...
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Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics. ...
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Typical Performance Characteristics I vs Input Voltage (Shutdown (Switching) Supply IN Frequency vs Temperature www.national.com Unless otherwise specified Input Voltage (Non-Switching) Supply 10135503 Switching Frequency vs R 10135535 Drive Voltage vs Input Voltage ...
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Current Sense Threshold vs Input Voltage Efficiency vs Load Current (3.3V In and 12V Out) Efficiency vs Load Current (9V In and 12V Out) COMP Pin Voltage vs Load Current 10135545 Efficiency vs Load Current (5V In and 12V Out) ...
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Error Amplifier Gain COMP Pin Source Current vs Temperature Compensation Ramp vs Compensation Resistor www.national.com Error Amplifier Phase 10135555 Short Circuit Sense Voltage vs Input Voltage 10135536 Shutdown Threshold Hysteresis vs Temperature 10135551 8 10135556 10135557 10135546 ...
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Duty Cycle vs Current Sense Voltage 10135594 9 www.national.com ...
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Functional Block Diagram Functional Description The LM3478 uses a fixed frequency, Pulse Width Modulated (PWM) current mode control architecture. The block diagram above shows the basic functionality typical application circuit, the peak current through the external MOSFET is ...
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Hence, the output voltage overshoot here can also trigger ...
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Sub-harmonic Oscillation can be easily understood as a ge- ometric problem. If the control signal does not have slope, the slope representing the inductor current ramps up until the control signal is reached and then slopes down again. If the ...
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FIGURE 6. Frequency Adjust FIGURE 7. Shutdown Operation in Frequency Adjust Mode SHORT-CIRCUIT PROTECTION When the voltage across the sense resistor measured on the Isen pin exceeds 343 mV, short circuit current limit protection gets activated. A comparator inside the ...
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A. First Cycle Operation B. Second Cycle of Operation POWER INDUCTOR SELECTION The inductor is one of the two energy storage elements in a boost converter. Figure 9 shows how the inductor current varies during a switching cycle. The current ...
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PROGRAMMING THE OUTPUT VOLTAGE AND OUTPUT CURRENT The output voltage can be programmed using a resistor di- vider between the output and the FB pin. The resistors are selected such that the voltage at the FB pin is 1.26V. Pick ...
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The off-state voltage of the MOSFET is approximately equal to the output voltage. Vds(max) must be greater than the out- put voltage. The power losses in the MOSFET can be cate- gorized into conduction losses and switching losses. Rds(on) is ...
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FIGURE 12. Current Flow In A Boost Application The PGND and AGND pins have to be connected to the same ground very close to the IC. To avoid ground loop currents, attach all the grounds of the system only at ...
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The peak switch current is given by: The rms current through the switch is given by: POWER DIODE SELECTION The Power diode must be selected to handle the peak current and the peak reverse voltage SEPIC, the diode ...
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L1. The energy bal- ance equation can be solved to provide a minimum value for Input Capacitor Selection Similar to a boost converter, the SEPIC has an inductor at the ...
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Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 20 ...
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Notes 21 www.national.com ...
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