lm5035bsqx National Semiconductor Corporation, lm5035bsqx Datasheet
lm5035bsqx
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lm5035bsqx Summary of contents
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... The oscillator can also be synchronized to an external clock. A current sense input and a pro- grammable timer provide cycle-by-cycle current limit and ad- justable hiccup mode overload protection. Simplified Application Diagram © 2009 National Semiconductor Corporation LM5035B Features ■ 105V / 2A Half-Bridge Gate Drivers ■ ...
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Connection Diagrams www.national.com Top View 20-Lead TSSOP EP Top View 30091303 LLP-24 Package 2 30091302 ...
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... Ordering Information Order Number Package Type LM5035BMH TSSOP-20EP LM5035BMHX TSSOP-20EP LM5035BSQ LLP-24 LM5035BSQX LLP-24 Pin Descriptions TSSOP LLP PIN Name PIN 1 23 RAMP Modulator ramp signal 2 24 UVLO Line Under-Voltage Lockout 3 2 OVP Line Over-Voltage Protection 4 3 COMP Input to the Pulse Width Modulator An external opto-coupler connected to the COMP pin sources ...
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TSSOP LLP PIN Name PIN Boost voltage for the HO driver Switch node High side gate drive output Low side gate drive output PGND Power Ground ...
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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 to GND HS to GND HB to GND VCC to GND RT, DLY to GND ...
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Symbol Parameter Soft-Start (SS Pin) I Charging current in normal SS operation Charging current during a hiccup mode restart Soft-stop Current Sink Oscillator (RT Pin) F Frequency 1 (at HO, half oscillator SW1 frequency) F Frequency 2 (at HO, half ...
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Symbol Parameter Thermal Shutdown T Shutdown temperature SD Hysteresis Thermal Resistance θ Junction to ambient, 0 LFPM Air JA Flow θ Junction to Case (EP) Thermal JC resistance θ Junction to ambient, 0 LFM Air Flow LLP- ...
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Typical Performance Characteristics V and V VCC REF REF REF Oscillator Frequency vs Temperature www.national.com vs V VIN 30091305 30091307 Soft-Start & Stop Current vs Temperature 30091309 VCC VCC 30091306 Frequency vs RT ...
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Effective Comp Input Impedance 30091311 SR "T1" Parameter vs Temperature 30091313 R vs Deadtime DLY SR "T2" Parameter vs Temperature 9 30091312 30091314 www.national.com ...
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Block Diagram www.national.com FIGURE 1. 10 30091304 ...
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Functional Description The LM5035B PWM controller contains all of the features necessary to implement half-bridge voltage-mode controlled power converters. The LM5035B provides two gate driver outputs to directly drive the primary side power MOSFETs and two signal level outputs to ...
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Cycle-by-Cycle Current Limit The CS pin is driven by a signal representative of the trans- former primary current. If the voltage sensed at CS pin ex- ceeds 0.25V, the current sense comparator terminates the output driver pulse. ...
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FIGURE 2. Current Limit Restart Circuit FIGURE 3. Current Limit Restart Timing 13 30091315 30091316 www.national.com ...
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Soft-Start The soft-start circuit allows the regulator to gradually reach a steady state operating point, thereby reducing start-up stress- es and current surges. When bias is supplied to the LM5035B, the SS pin capacitor is discharged by an internal MOSFET. ...
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VIN while the threshold of the clamp fixed voltage (2.5V). An example will illustrate the use of the Volt • Second Clamp comparator to achieve a 50% duty cycle limit at 200kHz ...
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Synchronous Rectifier Control Outputs (SR1 & SR2) Synchronous rectification (SR) of the transformer secondary provides higher efficiency, especially for low output voltage converters. The reduction of rectifier forward voltage drop (0.5V - 1.5V) to 10mV - 200mV V DS significantly ...
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Applications Information The following information is intended to provide guidelines for the power supply designer using the LM5035B. VIN The voltage applied to the VIN pin, which may be the same as the system voltage applied to the power transformer’s ...
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FIGURE 8. Current Sense Using Current Sense Transformer FIGURE 9. Current Sense Using Current Sense Resistor (R1) If the current sense resistor method is used, the over-current condition will only be sensed while LO is driving the low-side MOSFET. Over-current ...
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MOSFET. The capacitor should be large enough to supply the MOSFET gate charge (Qg) without dis- charging to the point where the drop in gate voltage affects the MOSFET value ten to twenty ...
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FIGURE 10. Basic UVLO Configuration FIGURE 11. Basic Over-Voltage Protection FIGURE 12. UVLO/OVP Divider 20 30091329 30091330 30091331 ...
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The impedance seen looking into the resistor divider from the UVLO and OVP pins determines the hysteresis level. UVLO and OVP enable and disable thresholds are calculated using Outputs disabled due to VIN falling below UVLO threshold Outputs enabled due ...
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R1 and Q1 are added reduce the sensitivity to low level currents in the opto-coupler. Using the values of Figure 14, the opto-coupler collector ...
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0.01 µ 363 µs. SS The time t2 provides a periodic cool-down time for the power converter in the event of a sustained overload or short circuit. This off time results in lower average ...
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Printed Circuit Board Layout The LM5035B Current Sense and PWM comparators are very fast, and respond to short duration noise pulses. The compo- nents at the CS, COMP, SS, OVP, UVLO, DLY and the RT pins should be as physically ...
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25 www.national.com ...
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Physical Dimensions www.national.com inches (millimeters) unless otherwise noted Molded TSSOP-20 NS Package Number MXA20A 24-Lead LLP Package NS Package Number SQA24B 26 ...
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Notes 27 www.national.com ...
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