LT1425CS Linear Technology, LT1425CS Datasheet
LT1425CS
Specifications of LT1425CS
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LT1425CS Summary of contents
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... Operating Frequency: 285kHz Easily Synchronized to External Clock Available in 16-Pin Narrow SO Package U APPLICATIONS Isolated Flyback Switching Regulators Ethernet Isolated 5V to – 9V Converters Medical Instruments Isolated Telecom Supplies , LTC and LT are registered trademarks of Linear Technology Corporation. U TYPICAL APPLICATION 5V to Isolated – 9V 500V ISOLATION BARRIER 5V T1* ...
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... Duty Cycle = 50 100 C J Duty Cycle = 50%, – Duty Cycle = 80% Duty Cycle = Minimum U W INFORMATION ORDER PART TOP VIEW NUMBER 16 GND 15 SHDN 14 R OCOMP LT1425CS 13 R CCOMP LT1425IS PGND 9 GND S PACKAGE = open 1.4V, unless otherwise specified. C MIN TYP MAX = 3.000k 402 ...
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ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER Load Compensation RCCOMP SW SYNC Function Minimum SYNC Amplitude Synchronization Range SYNC Pin Input Resistance Power Supply V Minimum Input Voltage IN(MIN) I Supply Current CC Shutdown Mode Supply Current Shutdown Mode Threshold ...
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LT1425 W U TYPICAL PERFORMANCE CHARACTERISTICS Feedback Amplifier Output Current vs R Pin Voltage REF 125 C 40 – –20 –40 –60 –80 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40 R NODE VOLTAGE ...
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PIN FUNCTIONS GND (Pins 16): Ground. These pins connect to the substrate of the die and are separate from the power ground and signal ground. They should connect directly to a good quality ground ...
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LT1425 W BLOCK DIAGRAM V IN 2.6V SHDN REGULATOR 285kHz SYNC OSCILLATOR W FLYBACK ERROR A PLIFIER DIAGRA FLYBACK ERROR AMPLIFIER LOGIC LOAD COMP COMPENSATION SGND V C GND IS OMITTED FOR CLARITY ...
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DIAGRA V SW VOLTAGE V IN GND SWITCH OFF STATE MINIMUM t ON FLYBACK AMP STATE U OPERATION The LT1425 is a current mode switching regulator IC that has been designed specifically for the ...
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LT1425 U OPERATION Within the dashed lines in the Block Diagram can be found the and R resistors. They are external REF FB OCOMP resistors on the user-programmable LT1425. The capaci- tor connected to the R pin ...
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U OPERATION regulation. See Applications Information section for fur- ther details. Enable Delay When the output switch shuts off, the flyback pulse appears. However, it takes a finite time until the trans- former primary side voltage waveform approximately rep- resents ...
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LT1425 U OPERATION may be minimized by the use of the load compensation function. To implement the load compensation function, a voltage is developed that is proportional to average output switch current. This voltage is then impressed across the external ...
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U U APPLICATIONS INFORMATION SELECTING R AND R RESISTOR VALUES FB REF The expression for V developed in the Operation OUT section can be rearranged to yield the following expres- sion for ...
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LT1425 U U APPLICATIONS INFORMATION amount when output switch current is zero. Please refer to Figure 1 which shows nominal reference current shift at zero load for a range of R OCOMP a load compensation resistor of 12k, the graph ...
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U U APPLICATIONS INFORMATION signal! It then reverts to a potentially stable state whereby the top of the leakage spike is the control point, and the trailing edge of the leakage spike triggers the collapse detect circuitry. This will typically ...
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LT1425 APPLICATIONS INFORMATION V of this diode should therefore be included calculations. Lot-to-lot and ambient temperature varia- tions will show up as output voltage shift/drift. Secondary Leakage Inductance Leakage inductance on the transformer secondary ...
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U U APPLICATIONS INFORMATION f OUT OUT(MIN SEC where Switching frequency (nominally 285kHz Transformer secondary side inductance SEC V = Output voltage OUT t = Enable delay time ...
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LT1425 U U APPLICATIONS INFORMATION Average supply current (including driver current) is 7mA + where Switch current switch duty cycle Switch power dissipation is given by: 2 ...
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U TYPICAL APPLICATIONS The following are several application examples of the LT1425. The first shows an isolated LAN supply which provides – 9V with 1% load regulation for output cur- rents of 0mA to 250mA. An alternate transformer, the Coiltronics ...
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LT1425 U TYPICAL APPLICATIONS 5V TO 15V + 22 F 35V 1 18.4k 2 0.1% 0 1000pF 7 3.01k 8 1% INPUT COM INPUT COM R1 3.3 F 24k ...
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... FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 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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... Isolated Flyback Mode for Higher Currents Uses Ultrasmall Magnetics 8-Pin Fixed Voltage Version of LT1425 330pF 100 MBRS340T3 220 F 220 F 10V 10V MMFT1N10E COILTRONICS VP1-0190 TURNS RATIO PER WINDING 407-241-7876 1425 TA05 1425fa LT/TP 1198 2K REV A • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1997 5V 1A 200 OUT COM ...