lm27342sdx National Semiconductor Corporation, lm27342sdx Datasheet
lm27342sdx
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lm27342sdx Summary of contents
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... Additional features include internal soft-start circuitry to reduce inrush current, pulse-by-pulse current limit, thermal shutdown, and output over-voltage protection. Typical Application Circuit © 2008 National Semiconductor Corporation Features ■ Space saving LLP-10 & eMSOP-10 package ■ ...
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... LM27342MY eMSOP -10 LM27342MYX eMSOP -10 LM27341SD LLP - 10 LM27341SDX LLP - 10 LM27342SD LLP - 10 LM27342SDX LLP - 10 Pin Descriptions Pin Name 1,2 SW Output switch. Connects to the inductor, catch diode, and bootstrap capacitor. 3 BOOST Boost voltage that drives the internal NMOS control switch. A bootstrap capacitor is connected between the BOOST and SW pins ...
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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. AVIN, PVIN SW Voltage Boost Voltage Boost to SW Voltage FB Voltage SYNC Voltage EN Voltage Storage Temperature Range ...
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Symbol Parameter INTERNAL MOSFET R Switch ON Resistance DS(ON) I Switch Current Limit CL D Maximum Duty Cycle MAX t Minimum on time MIN I Switch Leakage Current SW BOOST LDO V Boost LDO Output Voltage LDO THERMAL T Thermal ...
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Typical Performance Characteristics T = 25°C, unless specified otherwise. A Efficiency vs Load Current MHz OUT SW Refer to Figure 10 Efficiency vs Load Current V = 3.3V MHz OUT SW ...
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Line Transient 15V OUT Refer to Figure 13 Short Circuit Soft Start www.national.com = 3.3V 300056109 300056110 30005653 6 Line Transient 15V 3.3V IN OUT ...
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V = 12V 2.2 µ OUT OUT Refer to Figure 5V 1.8V 1.0 µ OUT OUT Refer to Figure 15 Sync Functionality = ...
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Oscillator Frequency vs Temperature V = GND, f SYNC Temperature FB Current Limit vs Temperature V = 12V IN www.national.com = 2 MHz 30005628 30005630 30005632 8 Oscillator Frequency 30005629 ...
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I (Shutdown) vs Temperature AVIN PVIN 30005634 30005635 www.national.com ...
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Block Diagram Application Information THEORY OF OPERATION The LM27341/LM27342 is a constant-frequency, peak cur- rent-mode PWM buck regulator IC that delivers a 1 load current. The regulator has a preset switching frequency of 2 MHz. This high frequency ...
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BOOST FUNCTION Capacitor C in Figure 1, commonly referred used to store a voltage V . When the LM27341/LM27342 BOOST starts up, an internal LDO charges C BOOST diode voltage sufficient to turn the ...
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FREQUENCY SYNCHRONIZATION The LM27341/LM27342 switching frequency can be synchro- nized to an external clock, between 1.00 and 2.35 MHz, applied at the SYNC pin. At the first rising edge applied to the SYNC pin, the internal oscillator is overridden and ...
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Please see Application note AN-1197 for further considerations. FIGURE 6. Recommended Ripple Ratio Vs. Duty Cycle The Duty Cycle (D) can be approximated quickly using the ratio of output voltage ( input voltage (V OUT The ...
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Their physical sizes are usually smaller than the Ferrite core inductors. The downside is their fringing flux and higher power dissipation due to relatively high AC loss, ...
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Calculating Efficiency, and Junction Temperature The complete LM27341/LM27342 DC-DC converter efficien- cy can be calculated in the following manner. Or Calculations for determining the most significant power loss- es are shown below. Other losses totaling less than 2% are not ...
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DIODE D1 OUT = 0. 0.314 IND OUT DCR = mΩ ...
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R values for the eMSOP @ 1Watt dissipation: θJA Number Size of Size of Top of Board Bottom Layer Layer Copper Layers Copper Connected to Connected to Dap DAP 0.5625 in 2 ...
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R of the application. The LM27341/LM27342 has over- θJA temperature protection circuitry. When the silicon tempera- ture reaches 165 °C, the device stops switching. The protection circuitry has a hysteresis of 15 °C. Once the silicon temperature has decreased to ...
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The dark grey, inner loop represents the high current path during the MOSFET on-time. The light grey, outer loop rep- resents the high current path during the off-time. GROUND PLANE AND SHAPE ROUTING The diagram of Figure 9 is also ...
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LM27341/LM27342 Circuit Examples FIGURE 10. V LM27342 Efficiency vs. Load Current Part Name Part ID Part Value Buck Regulator U1 1 Buck Regulator µF PVIN C C2 0.1 µF BOOST µF OUT ...
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FIGURE 11. V LM27342 Efficiency vs. Load Current Part Name Part ID Part Value Buck Regulator U1 1 Buck Regulator µF PVIN C C2 0.1 µF BOOST µF OUT ...
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FIGURE 12. V LM27342 Efficiency vs. Load Current Part Name Part ID Part Value Buck Regulator U1 1 Buck Regulator µF PVIN C C2 0.1 µF BOOST µF OUT ...
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FIGURE 13. V LM27342 Efficiency vs. Load Current Part Name Part ID Part Value Buck Regulator U1 1 Buck Regulator µF PVIN C C2 0.1 µF BOOST µF OUT ...
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FIGURE 14. V LM27342 Efficiency vs. Load Current Part Name Part ID Part Value Buck Regulator U1 1 Buck Regulator µF PVIN C C2 0.1 µF BOOST µF OUT ...
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FIGURE 15. V LM27342 Efficiency vs. Load Current Part Name Part ID Part Value Buck Regulator U1 1 Buck Regulator µF PVIN C C2 0.1 µF BOOST µF OUT ...
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FIGURE 16. V LM27342 Efficiency vs. Load Current Part Name Part ID Part Value Buck Regulator U1 1 Buck Regulator µF PVIN C C2 0.1 µF BOOST OUT ...
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FIGURE 17. V LM27342 Efficiency vs. Load Current Part Name Part ID Part Value Buck Regulator U1 1 Buck Regulator µF PVIN C C2 0.1 µF BOOST µF OUT ...
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Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 10-Lead LLP Package NS Package Number SDA10A 10-Lead eMSOP Package NS Package Number MUC10A 28 ...
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Notes 29 www.national.com ...
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