LM5026MT National Semiconductor, LM5026MT Datasheet
LM5026MT
Specifications of LM5026MT
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LM5026MT Summary of contents
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... PWM slope compensation, soft-start, 1MHz capable oscillator with synchronization input / output capabil- ity, precision reference and thermal shutdown. Typical Application Circuit Simplified Forward Power Converter with Active Clamp Reset © 2010 National Semiconductor Corporation LM5026 Features ■ Current Mode Control ■ ...
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... Connection Diagrams 16-Lead TSSOP Ordering Information Order Number Package Type LM5026MT TSSOP-16 LM5026MTX TSSOP-16 LM5026SD LLP-16 LM5026SDX LLP-16 Pin Descriptions Pin Name Description 1 VIN Input Voltage Source 2 UVLO Line Under-Voltage Lockout An external voltage divider from the power source sets the shutdown and ...
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Pin Name Description 9 OUT_B Active Clamp Output Driver 10 PGND Power Ground 11 AGND Analog Return 12 SS Soft-start 13 COMP Input to the Pulse Width Modulator 14 RT Oscillator Frequency Control Normally biased at 2V. The total external ...
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Block Diagram www.national.com FIGURE 1. Simplified Block Diagram 4 20147912 ...
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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 GND GND COMP Input Current All other inputs to GND Electrical Characteristics Specifications with standard typeface are for T perature range 48V 10V 30.0kΩ ...
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Symbol Parameter Over Current Restart Restart Threshold Fault Charging Current Discharging Current Soft-Start Soft-start Current Source Soft-stop Current Sink Soft-start Current Source following a restart event Oscillator Frequency1 Frequency2 SYNC Source Current SYNC Sink Impedance Can sync ...
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Symbol Parameter Thermal Shutdown T Thermal Shutdown SD Temp. Thermal Shutdown Hysteresis Thermal Resistance θ Junction to Ambient MTC Package JA SDA Package Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings ...
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Oscillator Frequency vs RT Overlap Time vs R Deadtime vs R www.national.com Oscillator Frequency vs Temperature 20147906 SET 20147908 SET 20147910 8 20147907 Overlap Time vs Temperature 20147909 Deadtime vs Temperature 20147911 ...
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Max Duty Cycle vs UVLO COMP Current vs INV PWM Comparator Voltage Max Duty Cycle vs DCL 20147935 20147937 9 20147936 www.national.com ...
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Detailed Operating Description The LM5026 PWM controller contains all of the features nec- essary to implement power converters utilizing the active clamp reset technique with current mode control. With the active clamp reset, higher efficiencies and greater power den- sities ...
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The rising edge overlap or deadtime and the falling edge overlap or deadtime are identical and are independent of op- erating frequency or duty cycle. The magnitude of the overlap/ deadtime can be calculated as follows: Overlap Time = 2.8 ...
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For duty cycles greater than 50 percent, current mode control circuits are subject to sub-harmonic oscillation. By adding an additional fixed slope voltage ramp signal (slope compensa- tion) to the current sense signal, this oscillation can be avoid- ed. The ...
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FIGURE 6. Maximum Duty Cycle vs UVLO Voltage Soft-Start/Soft-Stop The soft-start circuit allows the regulator to gradually reach a steady state operating point, thereby reducing start-up stress- es and current surges. Upon turn-on, the SS pin capacitor is discharged by ...
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For example, the Oscillator and Sync Capability The LM5026 oscillator frequency is set by the external resis- tance connected between the RT ...
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FIGURE 10. Oscillator Sync I/O Block Diagram Thermal Protection Internal Thermal Shutdown circuitry is provided to protect the integrated circuit in the event the maximum junction temper- ature is exceeded. When activated, typically at 165°C, the controller is forced into ...
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OSCILLATOR (RT, SYNC) Oscillator (RT, SYNC) The oscillator frequency is generally selected in conjunction with the design of the system mag- netic components along with the volume and efficiency goals for a given power converter design. The total RT resistance ...
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FIGURE 15. Current Sense Using a Current Sense Transformer FIGURE 16. Current Sense Using a Source Sense Resistor (R1) HICCUP MODE CURRENT LIMIT RESTART (RES) The basic operation of the hiccup mode current limit restart is described in the functional ...
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If the application requires no delay from the first detection of a current limit condition to the onset of the hiccup mode (t1 = 0), the RES pin can be left open (no external capacitor). ...
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Layout considerations are critical for the current sense filter current sense transformer is used, both leads of the trans- former secondary should be routed to the sense filter com- ponents and to the IC pins. The ground side ...
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Physical Dimensions inches (millimeters) unless otherwise noted Note recommended that the exposed pad be connected to Pin 11 (AGND). Molded TSSOP-16 NS Package Number MTC16 16-Lead LLP Surface Mount Package NS Package Number SDA16A 21 www.national.com ...
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