lm5574q0 National Semiconductor Corporation, lm5574q0 Datasheet
lm5574q0
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lm5574q0 Summary of contents
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... SIMPLE SWITCHER® 75V, 0.5A Step-Down Switching Regulator General Description The LM5574Q0 is an easy to use SIMPLE SWITCHER® buck regulator which allows design engineers to design and opti- mize a robust power supply using a minimum set of compo- nents. Operating with an input voltage range 75V, the LM5574Q0 delivers 0.5A of continuous output current with an integrated 750mΩ ...
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... Package Type LM5574Q0MT TSSOP-16 LM5574Q0MTX TSSOP-16 * Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including defect detection methodologies. Reliability qualification is compliant with the requirements and temperature grades defined in the AECQ100 standard. Automotive Grade products are identified with letter Q ...
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... This open drain output can be connected to SW pin to aid charging the bootstrap capacitor during very light load conditions or in applications where the output may be pre- charged before the LM5574Q0 is enabled. An internal pre- charge MOSFET is turned on for 250ns each cycle just prior to the on-time interval of the buck switch. ...
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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 GND IN BST to GND PRE to GND SW to GND (Steady State) BST ...
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Symbol Parameter RAMP GENERATOR Ramp Current 1 Ramp Current 2 PWM COMPARATOR Forced Off-time Min On-time COMP to PWM Comparator Offset ERROR AMPLIFIER Feedback Voltage FB Bias Current DC Gain COMP Sink / Source Current Unity Gain Bandwidth DIODE SENSE ...
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Soft Start Current vs Temperature 7kΩ L Demoboard Efficiency vs I www.national.com 30070747 IN 30070724 and V OUT IN 30070726 12V IN 30070723 Error Amplifier Gain/Phase ...
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Typical Application Circuit and Block Diagram 7 www.national.com ...
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... The device is available in the TSSOP-16 package. The functional block diagram and typical application of the LM5574Q0 are shown in Figure 1. The LM5574Q0 can be applied in numerous applications to efficiently step-down a high, unregulated input voltage. The device is well suited for telecom, industrial and automotive power bus voltage ranges. ...
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... Thus, if the SYNC pins of several LM5574Q0 IC’s are connected together, the IC with the highest internal clock fre- quency will pull the connected SYNC pins low first and termi- nate the oscillator ramp cycles of the other IC’ ...
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... In applications where the input voltage may be relatively large in comparison to the output voltage, controlling small pulsewidths and duty cycles is necessary for regulation. The LM5574Q0 utilizes a unique ramp generator, which does not actually measure the buck switch current but rather recon- structs the signal. Reconstructing or emulating the inductor ...
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FIGURE 6. Composition of Current Sense Signal The sample & hold DC level illustrated in Figure 6 is derived from a measurement of the re-circulating Schottky diode an- ode current. The re-circulating diode anode should be con- nected to the ...
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... Boost Pin The LM5574Q0 integrates an N-Channel buck switch and as- sociated floating high voltage level shift / gate driver. This gate driver circuit works in conjunction with an internal diode and an external bootstrap capacitor. A 0.022µF ceramic capacitor, connected with short traces between the BST pin and SW pin, is recommended ...
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... The worst case is to assume a short circuit load condition. In this case the diode will carry the output cur- rent almost continuously. For the LM5574Q0 this current can be as high as 0.7A. Assuming a worst case 1V drop across the diode, the maximum diode power dissipation can be as high as 0 ...
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... R4 and C5. The overall loop gain is the product of the modulator gain and the error ampli- fier gain. The DC modulator gain of the LM5574Q0 is as follows: DC Gain The dominant low frequency pole of the modulator is deter- ...
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These values configure the compensation network zero at 290Hz. The error amp gain at frequencies greater than f is R5, which is approximately 5 (14dB). Z FIGURE 10. Error Amplifier Gain and Phase The overall loop can ...
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FIGURE 12. VCC Bias from VOUT for 8V < VOUT < 14V FIGURE 13. VCC Bias with Additional Winding on the Output Inductor www.national.com 30070718 30070719 16 ...
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... LFM (Linear Feet per Minute). With a 25°C ambient temperature and no airflow, the predicted junction temperature for the LM5574Q0 will ((90 x 0.6) = 79°C. If the evaluation board is operated at 0.5A output current, 70V input voltage and high ambient temperature for a prolonged period of time the thermal shutdown protection within the IC may activate ...
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Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 16-Lead TSSOP Package NS Package Number MTC16 18 ...
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Notes 19 www.national.com ...
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