SC4905B Semtech Corporation, SC4905B Datasheet
SC4905B
Related parts for SC4905B
SC4905B Summary of contents
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... Feeding the oscillator of one device to the SYNC of another forces biphase operation (180 degrees apart) which reduces input ripple and filter size. The SC4905A has a typical turn-on threshold of 4.4V and the SC4905B has a typical turn-on threshold of about 11.6 volts. These devices are available in the 10 lead MSOP package. ...
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POWER MANAGEMENT Absolute Maximum Ratings Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied ...
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POWER MANAGEMENT Electrical Characteristics (Cont.) Unless otherwise specified 12V 48V ...
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POWER MANAGEMENT Pin Configuration (Top view) VDD FB VFF DMAX RC (MSOP-10) 2006 Semtech Corp. Ordering Information REF ...
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POWER MANAGEMENT Pin Descriptions VDD: The supply input for the device. Once VDD has ex- ceeded the UVLO limit, the internal reference, oscillator, drivers and logic are powered up. This pin should be by- passed with a low ESR capacitance ...
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... POWER MANAGEMENT Block Diagram Marking Information SC4905AIMSTR SC4905BIMSTR Top Mark Top Mark ALOA ALOB yyww Bottom Mark Bottom Mark xxxx xxxx xxxx xxxx 2006 Semtech Corp. yyww yyww = Date Code (Example: 0012) xxxx = Semtech Lot No. (Example: E901 xxxx 6 SC4905A/B 01-1) www.semtech.com ...
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... Two voltage options are available for the SC4905. The SC4905A version has a typical VDD under voltage of 4.4V, and a 4V reference, while the SC4905B version provides a 11.6V VDD UVLO, and a 5V reference. The Oscillator frequency is programmed by a resistor and a capacitor network connected to the line supply voltage . ...
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... POWER MANAGEMENT Application Information (Cont.) VDD UNDER VOLTAGE LOCK OUT According to the application, and the voltages available, the SC4905A (UVLO = 4.4V), or the SC4905B (UVLO = 11.6V) can be used to provide the VDD undervoltage lock out function to ensure the converters controlled start up. Before the VDD UVLO has been reached, the internal ref- erence, oscillator, OUT driver, and logic are disabled ...
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POWER MANAGEMENT Application Information (Cont.) FEED FORWARD & MAXIMUM DUTY CYCLE The feed forward function provided by the SC4905 will improve the dynamic performance of the converter in response to the changes in the input supply. In voltage mode controllers ...
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POWER MANAGEMENT Application Information (Cont.) FEED BACK The error signal from the output of an external Error am- plifier such as SC431 or SC4431 is applied to the invert- ing input of the PWM comparator at the FB pin either ...
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POWER MANAGEMENT Application Information (Cont.) START UP SEQUENCE Initially during the power up, the SC4905 is in the under voltage lock out condition. As the VDD supply exceeds the UVLO limit of the SC4905 and the VFF pin exceeds the ...
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POWER MANAGEMENT Application Information (Cont.) LAYOUT GUIDELINES Careful attention to layout requirements are necessary for successful implementation of the SC4905 PWM control- ler. High currents switching are present in the application and their effect on ground plane voltage differentials must ...
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POWER MANAGEMENT Typical Step Load Vout 20mV/Div Iout 0.5A/Div Cout = 6X100uF (600uF) Tantalum Typical SC4905 Forward converter Step Load plot at Vin = 48V, Vout = 12V, Step = 50% to 75% Iout, Fosc = 245kHz 2006 Semtech Corp. ...
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POWER MANAGEMENT SC4905A Typical Characteristics (SC4808A -40 -25 - (°C) Iq (start up) vs. Temperature 3.200 3.100 3.000 2.900 2.800 2.700 2.600 -40 -25 - ...
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POWER MANAGEMENT SC4905A Typical Characteristics (Cont.) 0.250 0.240 0.230 0.220 0.210 0.200 0.190 0.180 0.170 -40 -25 - (°C) Vdd UVLO Hysteresis vs. Temperature 1.240 1.220 1.200 1.180 1.160 1.140 1.120 1.100 1.080 -40 -25 ...
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POWER MANAGEMENT SC4905A Typical Characteristics (Cont.) 1.792 1.790 1.788 1.786 1.784 1.782 1.780 1.778 -40 -25 - (°C) Synchronization Threshold vs. Temperature 280 260 240 220 200 180 160 140 120 100 -40 -25 -10 ...
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... POWER MANAGEMENT SC4905B Typical Characteristics -40 -25 - (°C) Iq (start up) vs. Temperature 3.460 3.410 3.360 3.310 3.260 3.210 3.160 3.110 3.060 -40 -25 - (°C) Idd (operating) vs. Temperature 5.030 5.025 5.020 5.015 5.010 5.005 5 ...
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... POWER MANAGEMENT SC4905B Typical Characteristics (Cont.) 3.740 3.720 3.700 3.680 3.660 3.640 3.620 3.600 3.580 -40 -25 - (°C) Vdd UVLO Hysteresis vs. Temperature 1.240 1.220 1.200 1.180 1.160 1.140 1.120 1.100 1.080 -40 -25 - (°C) Line UVLO vs. Temperature 101 ...
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... POWER MANAGEMENT SC4905B Typical Characteristics (Cont.) 1.796 1.794 1.792 1.790 1.788 1.786 1.784 -40 -25 - (°C) Synchronization Threshold vs. Temperature 190 180 170 160 150 140 130 120 110 100 -40 -25 - (°C) FB pin leakage current vs. Temperature 2006 Semtech Corp. ...
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POWER MANAGEMENT Evaluation Board Schematics 2006 Semtech Corp. 20 SC4905A/B www.semtech.com ...
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POWER MANAGEMENT Evaluation Board Bill of Materials Revised: Monday, March 8, 2003 SC4905 Single Switch Forward (RCD Reset) non Synchronous 12V 50W Bill Of Materials Revised: January 28,2002 Item Quantity Reference 1 1 CON1 2 1 CON2 3 2 C11,C1 ...
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POWER MANAGEMENT Evaluation Board Gerber Plots Board Layout Assembly Top Board Layout Top 2006 Semtech Corp. Board Layout Assembly Bottom Board Layout Bottom 22 SC4905A/B www.semtech.com ...
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POWER MANAGEMENT Evaluation Board Gerber Plots Board Layout INNER1 Board Layout INNER2 2006 Semtech Corp. 23 SC4905A/B www.semtech.com ...
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... SEE DETAIL SIDE VIEW -A- AND - DETERMINED AT DATUM PLANE -H- X DIM INCHES (.161) C (C) G .098 .020 X .011 Y .063 Z .224 Y P Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 24 SC4905A/B DIMENSIONS INCHES MILLIMETERS NOM MAX - - - .043 1. .006 0.00 0. .037 0.75 0. ...