LTC3725EMSE#PBF Linear Technology, LTC3725EMSE#PBF Datasheet

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... Voltage feedforward pro- vides excellent line regulation and transient response. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. PolyPhase is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Patent Pending T1 • ...

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LTC3725 ABSOLUTE AXI U RATI GS (Note 1) Power Supply (V ) ...................................– 0.3V to 15V CC External NMOS Drive (NDRV) ....................– 0.3V to 20V NDRV ........................................................... Soft-Start Fault, Feedback, Frequency Set, Transformer + ...

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ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER I Hysteresis Current HUVLO V Voltage Feedforward Operating Range UVLOOP Gate Driver (GATE) R Output Pull-Down Resistance OS V High Output Voltage OH I Peak Pull-Up Current PU t ...

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LTC3725 W U TYPICAL PERFOR A CE CHARACTERISTICS Supply Current 2.0 TRICKLE CHARGER 1.5 LINEAR REGULATOR 1.0 0 (V) CC 3725 G01 Oscillator Frequency OSC FSET 800 700 ...

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W U TYPICAL PERFOR A CE CHARACTERISTICS Gate Drive Pull-Down Resistance vs Temperature 2.50 2.25 2.00 1.75 1.50 –60 –40 – TEMPERATURE (°C) Linear Regulator Start- 5V/DIV NDRV V CC 3725 G12 25µs/DIV Gate Drive Peak ...

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LTC3725 CTIO S UVLO (Pin 1): Undervoltage Lockout. Connect to a resis- tive voltage divider to monitor input voltage V converter operation for V > 1.242V. Hysteresis is a UVLO fixed 16mV hysteresis voltage with ...

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W BLOCK DIAGRA + 8V NDRV 3 – 0.6V + – I NDRV 0.27mA + – SSFLT 1.242V + 1.226V UVLO 1 – 0.66 4.9µA GND 11 (PAD – CONDITION IN PRIMARY SIDE CONTROL ...

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LTC3725 U OPERATIO Mode Setting The LTC3725 is a controller and gate driver designed for use in a single-switch forward converter. When used in conjunction with the LTC3706 PolyPhase secondary- side synchronous forward controller, it forms a complete forward converter ...

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U OPERATIO Self-Starting Architecture The LTC3725 is combined with the LTC3706 to form a complete self-starting DC isolated power supply. When power is first applied, and when V above the appropriate threshold, the LTC3725 begins open-loop operation using its own ...

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LTC3725 U OPERATIO exceeds 1.26V the gate drive is immediately turned “off.” Note that this is not considered a fault condition and the LTC3725 can run indefinitely with the switch duty cycle being determined by the volt-second limit circuit. The ...

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U U APPLICATIO S I FOR ATIO UVLO The UVLO pin is connected to a resistive voltage divider connected shown in Figure 2. The voltage IN threshold on the UVLO pin for V IN introduce hysteresis, the ...

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LTC3725 U U APPLICATIO S I FOR ATIO However, care should be taken to ensure that soft-start transfer from primary-side to secondary-side is com- pleted well before the output voltage reaches its target value. A good design goal is to ...

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U U APPLICATIO S I FOR ATIO Since the power dissipation of the linear regulator is proportional to the input voltage, this strategy of making the timeout inversely proportional to the input voltage produces an approximately constant temperature excur- sion ...

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LTC3725 U U APPLICATIO S I FOR ATIO Auxiliary Supply When used with the LTC3706, the LTC3725 does not require an auxiliary supply to provide primary-side gate- drive bias current. After start-up, primary-side gate drive current is provided by the ...

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U U APPLICATIO S I FOR ATIO + V IN – Standalone Primary-Side Operation The LTC3725 can be used to implement a standalone forward converter using optoisolator feedback and a secondary-side voltage reference. Alternately the LTC3725 can be ...

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LTC3725 U U APPLICATIO S I FOR ATIO Effective grounding can be achieved by considering the return current paths from the sense resistor to each respective bypass capacitor. Don’t be tempted to run small traces to separate the grounds. A ...

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U TYPICAL APPLICATIO S LTC3725 3725fa 17 ...

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LTC3725 U TYPICAL APPLICATIO 10µF 25V 12V 10µF 10µF 25V 25V – MMBD914 MMBD914 NDRV GATE 115k 1 UVLO LTC3725 15k 2 SSFLT VSLMT PGND 1µ ...

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... LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 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. ...

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... Operation, Synchronous Switch Output Regulates Two Secondary Outputs, Optocoupler Feedback Driver and Second Output Synchronous Driver Controller Similar Function to LTC3900, Used in Full-Bridge and Push-Pull Converter www.linear.com ● Range: 4.5V to 12V CC 3725fa LT 1006 REV A • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2005 ...