SC4808B Semtech Corporation, SC4808B Datasheet
SC4808B
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SC4808B Summary of contents
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... Push-Pull, Half Bridge and Full Bridge format with programmable dead time between two outputs depending on the size of the timing components. The SC4808 also features a turn on threshold of 12V for SC4808A and 4.4V for SC4808B. They are available in MSOP-10 packages. Typical Application Circuit Vin RSENSE ...
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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 specified: VCC = 12V 100pF ...
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POWER MANAGEMENT Pin Configuration Top View (MSOP-10) 2005 Semtech Corp. Ordering Information ...
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... This pin can also function as an Enable/Disable. SYNC: SYNC is a positive edge triggered input with a thresh- old set to 1.6V (SC4808A), and 1.0V (SC4808B single controller operation, SYNC could be grounded or connected to an external synchronization clock within the SYNC frequency range (see page 3) ...
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... Datecode (Example: 9912) xxxx = Semtech Lot # (Example: E901 xxxx 2005 Semtech Corp. CS Slope Comp. OVER CURRENT Peak Current Enable OSC 500mv SOFT START R SYNC SYNC SC4808BIMSTR, SC4808BIMSTRT 6 SC4808A/B Disable LUVLO R Top Mark ABOB yyww Bottom Mark xxxx xxxx 01-1) www.semtech.com ...
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POWER MANAGEMENT SC4808A Typical Characteristics (SC4808A) 100 -40 -25 - (°C) Iq (start up) vs. Temperature 4.40 4.30 4.20 4.10 4.00 3.90 3.80 -40 -25 - ...
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POWER MANAGEMENT SC4808A Typical Characteristics (Cont.) 5.00 4.80 4.60 4.40 4.20 4.00 3.80 3.60 3.40 3.20 3.00 -40 -25 - (°C) Vcc UVLO Hysteresis vs. Temperature 5.030 5.025 5.020 5.015 5.010 5.005 5.000 4.995 4.990 ...
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POWER MANAGEMENT SC4808A Typical Characteristics (Cont.) 220 200 180 160 140 120 100 80 -40 -25 - (°C) Soft Start Delay time vs. Temperature 2005 Semtech Corp. Soft Start Delay Time 110 ...
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... POWER MANAGEMENT SC4808B Typical Characteristics (SC4808A) 100.0 95.0 90.0 85.0 80.0 75.0 70.0 -40 -25 - (°C) Iq (start up) vs. Temperature 3.90 3.85 3.80 3.75 3.70 3.65 3.60 -40 -25 - (°C) Iq (operating) vs. Temperature 3.22 3.21 3.2 3.19 3.18 3.17 3.16 -40 -25 - (°C) Reference vs. Temperature 2005 Semtech Corp. 1.69 Start up Iq, Vcc = 4V 1.68 1.67 1.66 1.65 1.64 1.63 1.62 1.61 1. 110 125 -40 - Offset vs. Temperature ...
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... POWER MANAGEMENT SC4808B Typical Characteristics (Cont.) 100 -40 -25 - (°C) Vcc UVLO Hysteresis vs. Temperature 3.170 3.165 3.160 3.155 3.150 3.145 3.140 3.135 3.130 3.125 3.120 -40 -25 - (°C) Line UVLO vs. Temperature 140 135 ...
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... POWER MANAGEMENT SC4808B Typical Characteristics (Cont.) 180 170 160 150 140 130 120 110 100 90 80 -40 -25 - (°C) Soft Start Delay time vs. Temperature 2005 Semtech Corp. Soft Start Delay Time 110 125 12 SC4808A/B www.semtech.com ...
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... Two voltage options are available for the SC4808. The SC4808A ver- sion has a typical VCC under voltage of 12.0V and a 5V reference. The SC4808B version provides a 4.4V VCC UVLO, and a 3.125V reference. The oscillator frequency is pro- grammed by a resistor and a capacitor network connected to an external reference provided by the SC4808 ...
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... Application Information (Cont.) VCC UNDER VOLTAGE LOCK OUT Depending on the application and the voltages available, the SC4808A (UVLO = 12.0V), or the SC4808B (UVLO = 4.4V) can be used to provide the VCC undervoltage lock out function to ensure the converters controlled start up. Before the VCC UVLO has been reached, the internal refer- ence, oscillator, OUTA/OUTB drivers, and logic are disabled ...
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... SYNC is a positive edge trig- gered input with a threshold set to 1.6V (SC4808A), and 1.0V (SC4808B single controller operation, SYNC should be grounded or connected to an external synchronization clock within the SYNC frequency range (see page 3). ...
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POWER MANAGEMENT Application Information (Cont.) which might cause negative voltages at the output of the drivers. This negative voltage can be clamped to a reason- able level by placing a small Schottky diode directly at the output of the driver ...
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POWER MANAGEMENT Application Information (Cont.) SLOPE COMPENSATION (Current or Voltage mode of operation) In applications where a current mode control is used for regulation, the peak inductor current information is used to produce the average output current small ...
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POWER MANAGEMENT Application Information (Cont.) The instability can be corrected by modification of the peak current information slope. One of the methods to alter the peak current information is to add a positive going ramp to the output of the ...
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POWER MANAGEMENT Application Information (Cont all Inductor current perturbation Inductor current Sensed Mosfet current Sens Sum m ation of Isense and slope com pensation, at the CS pin ...
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POWER MANAGEMENT Application Information (Cont.) Below the benefits from the slope compensation become apparent. The top wave form shows the stable operation before the perturbation. The second wave form shows the perturbation and the instability caused from ...
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POWER MANAGEMENT Application Information (Cont.) SOFT START During start up of the converter, the discharged output ca- pacitor and the load current have large supply current re- quirements. To avoid this a soft start scheme is usually implemented where the ...
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POWER MANAGEMENT Application Information (Cont.) LAYOUT GUIDELINES Careful attention to layout requirements are necessary for successful implementation of the SC4808 PWM control- ler. High current switching is present in the application and their effect on ground plane voltage differentials must ...
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POWER MANAGEMENT Gain & Phase Margin 50 40 Phase -10 -20 -30 10 Typical SC4808 Push Pull Converter Gain/Phase plot at Vin = 36V, Vout = 3.3V, Iout = 10A, Fosc = 650kHz 2005 Semtech Corp. ...
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POWER MANAGEMENT Gain & Phase Margin (Cont Phase -10 -20 -30 10 Typical SC4808 Push Pull Converter Gain/Phase plot at Vin = 48V, Vout = 3.3V, Iout = 10A, Fosc = 650kHz 2005 Semtech ...
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POWER MANAGEMENT Gain & Phase Margin (Cont Phase -10 -20 -30 10 Typical SC4808 Push Pull Converter Gain/Phase plot at Vin = 72V, Vout = 3.3V, Iout = 10A, Fosc = 650kHz 2005 Semtech ...
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POWER MANAGEMENT Typical Step Load Vout 500mV/Div Iout 5A/Div Cout = 6X22uF (132uF) Ceramic Typical SC4808 Push Pull Converter Step Load plot at Vin = 48V, Vout = 3.3V, Step = 37% to 75% Iout, Fosc = 650kHz 2005 Semtech ...
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POWER MANAGEMENT Evaluation Board Schematics 2005 Semtech Corp. 27 SC4808A/B www.semtech.com ...
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POWER MANAGEMENT Evaluation Board Bill of Materials SC4808 Push Pull 3.3V 50W non Synchronous SC4808EVB__non_sync Revision: 1.1 Bill Of Materials October 7,2002 Item Quantity Reference 1 1 CON1 2 1 CON2 3 2 C3, C2,C10,C17,C24,C26,C32 5 6 C4,C5,C6,C7,C8,C9 ...
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POWER MANAGEMENT Evaluation Board Gerber Plots Board Layout Assembly Top Board Layout Top 2005 Semtech Corp. Board Layout Assembly Bottom Board Layout Bottom 29 SC4808A/B www.semtech.com ...
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POWER MANAGEMENT Evaluation Board Gerber Plots Board Layout INNER1 2005 Semtech Corp. Board Layout INNER2 30 SC4808A/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 Y Z .224 P Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 31 SC4808A/B DIMENSIONS INCHES MILLIMETERS NOM MAX - - - .043 1. .006 0.00 0. .037 0.75 0. ...