LT1105IN8 Linear Technology, LT1105IN8 Datasheet

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... The LT1103/LT1105 current mode switching techniques are well suited to transformer isolated flyback and forward topologies while providing ease of frequency compensa- tion with a minimum of external components. Low exter- nal part count for a typical application combines with a , LTC and LT are registered trademarks of Linear Technology Corporation. MBR2045 1.5KE300A 5W + MUR150 *OUTPUT CAPACITOR IS THREE 1200µ ...

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LT1103/LT1105 U DESCRIPTION 200kHz maximum switching frequency to achieve high power density. Performance at switching frequencies above 100kHz may be degraded due to internal timing constraints associated with fully isolated flyback mode. Included are the oscillator, control, and protection cir- ...

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... I = 30mA 4V Open, Measured OVLO = 5V SF/C 40kHz < f OSC OSC, OSC LT1103/LT1105 TOP VIEW ORDER PART NUMBER 15V LT1105CN8 LT1105IN8 4 5 OSC N8 PACKAGE 8-LEAD PDIP = 100 C, = 130 C/W JMAX JA FRONT VIEW ORDER PART NUMBER 7 15V OSC 4 GND LT1103CT7 PACKAGE 7-LEAD TO-220 ...

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LT1103/LT1105 ELECTRICAL CHARACTERISTICS V = 20V 0.85V, OVLO = 0V, V Open SYMBOL PARAMETER DC Preset Max Switch Duty Cycle (LT1103) Preset Max Switch Duty Cycle (LT1105) OVLO Threshold OVLO Input Bias Current V ...

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ELECTRICAL CHARACTERISTICS V = 20V 0.85V, OVLO = 0V, V Open SYMBOL PARAMETER Switch Output Low Level (LT1105) Rise Time (LT1105) Fall Time (LT1105) I Threshold Voltage (LT1105) LIM Low Switch Drive Lockout Threshold ...

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LT1103/LT1105 W U TYPICAL PERFORMANCE CHARACTERISTICS Quiescent Supply Current vs Temperature 22 21 30V –50 – 100 125 150 175 –75 TEMPERATURE (°C) LT1103 G04 V ...

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W U TYPICAL PERFORMANCE CHARACTERISTICS OVLO Input Bias Current vs Temperature 0 OVLO = 2V –0.5 –1.0 –1.5 –2.0 –2.5 –3.0 –75 –50 – 100 125 150 175 TEMPERATURE (°C) LT1103 G13 5V Reference Voltage vs ...

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LT1103/LT1105 W U TYPICAL PERFORMANCE CHARACTERISTICS 15V Gate Bias Short-Circuit Current vs Temperature 130 110 –75 – 100 125 – 150 TEMPERATURE ( C) LT1103 G22 Feedback Threshold vs Temperature 4.60 4.56 ...

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W U TYPICAL PERFOR A Error Amplifier Source Current vs Temperature 350 325 300 275 250 225 200 175 150 100 –75 –50 – 125 150 175 TEMPERATURE (°C) LT1103 G31 Error Amplifier Low Clamp Voltage ...

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LT1103/LT1105 W U TYPICAL PERFOR A LT1103 Driver Current vs Temperature –75 – 100 125 175 –50 0 150 TEMPERATURE (°C) LT1103 G41 LT1105 Current Limit Threshold Voltage vs Temperature 450 ...

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PIN FUNCTIONS LT1103 FB: The Feedback pin is the inverting input to the sampling error amplifier. The noninverting input is tied to a 4.5V reference. The FB pin is used for output voltage sensing. The input bias ...

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LT1103/LT1105 W BLOCK DIAGRA S 15V GATE 15V BIAS START-UP 16V REF FB 0VLO 2.5V 12 LT1103 OSC GATE BIAS DETECT OSCILLATOR LOGIC COMP 4.5V + – SAMPLING ERROR AMP g = 0.012 m ...

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W BLOCK DIAGRA S 15V GATE 15V BIAS START-UP 16V REF FB 0VLO 2.5V LT1105 OSC GATE BIAS DETECT OSCILLATOR LOGIC COMP 4.5V + – SAMPLING ERROR AMP g = 0.012 m SHUT DOWN ...

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LT1103/LT1105 U OPER ATIO LT1103 The LT1103 is a current mode switcher. Switch duty cycle is controlled by switch current rather than directly by the output voltage. Referring to the block diagram, the switch is turned on at the start ...

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U OPER ATIO Control of output voltage is obtained by using the output of a voltage sensing error amplifier to set current trip level. This technique has several advantages. First, it has imme- diate response to input voltage variations, unlike ...

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LT1103/LT1105 U U APPLICATIONS INFORMATION Bootstrap Start It is inefficient as well as impractical to power a switching regulator control IC from the rectified DC input as this voltage is several hundred volts. Self-biased switching regulator topologies take advantage of ...

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U U APPLICATIONS INFORMATION SS is reset to 0V whenever V is less than 7V (prestart IN mode) or when shutdown is activated by pulling V 0.15V. The SS pin has a guaranteed reset sink current of 1mA when either ...

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LT1103/LT1105 U U APPLICATIONS INFORMATION low resistance for best performance. This will help minimize voltage spikes associated with the high dI/dt switch current. Avoiding long wire runs to the ground pin minimizes load regulation effects and inductive voltages created by ...

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U U APPLICATIONS INFORMATION A special circuit in the LT1103 senses the voltage at V prior to turning on the switch the FET and should represent the bias voltage on the gate when the switch is off. When ...

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LT1103/LT1105 U U APPLICATIONS INFORMATION The LT1105 provides a 15V regulated output intended for driving the totem-pole output stage. It will source 30mA into a capacitive load with no stability problems. The output voltage temperature coefficient is 3mV ...

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U U APPLICATIONS INFORMATION voltage, the secondary voltage, the bias voltage and the winding currents are indicated in the figures found on the following page for both continuous and discontinuous modes of operation. Simplified Flyback Converter V IN L(Ik ) ...

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LT1103/LT1105 U U APPLICATIONS INFORMATION Flyback Waveform for Continuous Mode Operation )[L(lk )]/V PRI PRI SNUB Flyback Waveform for Discontinuous Mode Operation V ZENER PRIMARY SWITCH ...

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U U APPLICATIONS INFORMATION time is the most accurate representation of the output voltage, the answer given by the bias winding voltage is still off from the “true” answer by the amount I•R The sampling error amplifier of the LT1103/LT1105 ...

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... LT1103/LT1105 is to use transient response techniques and an “RC” box to quickly iterate toward the final compensation network. Additional information on this technique of frequency compensation can be found in Linear Technology’s Application Note 19. In general, frequency compensation is accomplished with an RC series network on the V pin. The error amplifier has ...

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U U APPLICATIONS INFORMATION where N is the transformer turns ratio of secondary to primary and DC is the duty cycle. This formula can be rewritten in terms of duty cycle as: V OUT • V ...

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LT1103/LT1105 U U APPLICATIONS INFORMATION V in continuous mode is defined as: OUT • N • DC OUT IN The secondary voltage charges up L1 through D1 when S1 is on. When S1 is off, energy in ...

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U TYPICAL APPLICATIONS Setting Oscillator Frequency LT1103/LT1105 OSC C OSC LT1103 TA05 CHOOSE 20kHz f 200kHz OSC OSC OSC OSC DC 0.66 66% Decreasing Oscillator Maximum Duty Cycle 5V LT1105 OSC R ...

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LT1103/LT1105 U TYPICAL APPLICATIONS LT1103 TA11a 28 LT1103 Ground Connections 15V SWITCH CURRENT PATH V IN KEEP RESISTANCE LOW OSC GND BIAS WINDING OUTPUT SEPARATE GROUND PATH SWITCH CURRENT PATH KEEP RESISTANCE LOW 15V ...

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PACKAGE DESCRIPTION 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) +0.035 0.325 –0.015 +0.889 8.255 –0.381 *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) U ...

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LT1103/LT1105 PACKAGE DESCRIPTION 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) +0.035 0.325 –0.015 +0.889 8.255 –0.381 *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) ...

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... Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U Dimensions in inches (millimeters) unless otherwise noted ...

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... CAPACITORS IN PARALLEL TO ACHIEVE REQUIRED RIPPLE CURRENT RATING AND LOW ESR. WINDINGS FOR OPTIONAL 12V OUTPUTS DC TRANSFORMER DATA: COILTRONICS - CTX110228 1.6mH (PRI 1:0.05 PRI SEC 1:0.27 BIAS SEC LT1103 TA01 11035fd LT/TP 0998 REV D 2K • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1992 ...