SC2447 Semtech Corporation, SC2447 Datasheet
SC2447
Related parts for SC2447
SC2447 Summary of contents
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... Inductor DC resis- tance sensing has the advantage of being lossless. Each phase has individual closed-loop soft-start and over- load shutdown timer. The SC2447 powers up neatly with pre-biased output. It has tri-state shutdown and hiccup overload protection. In two-phase single-output configu- ration, the master timer controls the soft-start and over- load shutdown functions ...
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... GDL2 GDH2 AVCC SS2/EN2 SC2447 www.DataSheet4U.com ...
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... ° SC2447 www.DataSheet4U.com ...
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... SC2447 www.DataSheet4U.com ...
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... < I < < < SC2447 www.DataSheet4U.com ° ...
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... POWER MANAGEMENT Typical Performance Characteristics © 2006 Semtech Corp SC2447 www.DataSheet4U.com www.semtech.com ...
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... OUT1 5A/div I =15A to 20A 200µs/div OUT1 Pre-biased Start OUT2 V OUT2 0.5V/div V SS2/EN2 2V/div I OUT2 20A/div I =0A 10ms/div OUT2 7 SC2447 www.DataSheet4U.com = 25°C. A Shutdown (V ) OUT1 V OUT1 1V/div I OUT1 2A/div V SS1/EN1 5V/div V GDL1 5V/div R =1Ω 200µs/div OUT1 Overload Hiccup (V ...
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... OUT2 V OUT2 0.1V/div I OUT2 5A/div I =20A to 25A 200µs/div OUT2 =0.4uH for V = 1.2V, L =1uH for V = 2.5V, 3.3V, and 5.0V, R OUT OUT OUT OUT 8 SC2447 www.DataSheet4U.com = 51.1kΩ, SYNC = 0, and T = 25°C. OSC A Overload Hiccup (V ) OUT2 V OUT2 0.5V/div V SS2/EN2 2V/div I OUT2 20A/div 50ms/div = 51.1kΩ, and T = 25° ...
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... SS1/EN1 2V/div I OUT 20A/div I =0A 10ms/div OUT Load Transient Response (V ) OUT V OUT 0.1V/div I OUT 10A/div I =40A to 50A 200µs/div OUT2 9 SC2447 www.DataSheet4U.com = 25°C. A Shutdown (V ) OUT V OUT 0.5V/div I OUT 1A/div V SS1/EN1 5V/div V GDL1 5V/div R =1Ω 200µs/div OUT2 Overload Hiccup (V ...
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... SC2447 www.DataSheet4U.com ...
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... CONTROL 1 SEL CLK2 ANALOG SWITCH PWM2 S + TGON2 UV CLK2 PRE-BIAS SOFT-START OL2 OC2 & DSBL2 OVERLOAD SSL2 HICCUP SS2/EN2 CONTROL 2 Figure 3. SC2447 Block Diagram 11 SC2447 www.DataSheet4U.com REFERENCE 0.5V TRI-STATE1 SS1/EN1 1.25V 2R R UVLO 4.3/4. MUX Y TRI-STATE2 1.25V R 2R REFSS2 www.semtech.com AVCC 16 GDH1 ...
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... POWER MANAGEMENT Block Diagram 2.85V - + 9.5uA SS/EN 17.0uA UV Figure 4. Soft-Start and Overload Hiccup Control Circuit 2006 Semtech Corp. S 0.5V/3. 0.8V (0.6V min 46.5uA S 12 SC2447 www.DataSheet4U.com OL COMP SSL S DSBL Q R TGON CLK OC www.semtech.com ...
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... Normal Start VCC VCC V V SS/EN SS/ COMP COMP V V REFSS REFSS V V IN- IN- GDH GDH GDL GDL Figure 6. SC2447 UVLO Shutdown Timing Diagram 2006 Semtech Corp. V SS/EN 3.2V Enable Hiccup V COMP 0 V REFSS V IN- 0 GDH 0 GDL Figure 5. SC2447 Start-up Timing Diagram 4.3V 4.3V 0.5V (V 0.5V (V ...
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... POWER MANAGEMENT Timing Chart 3.2V Enable Hiccup 2.85V 1.50V 1.25V 0.8V 0.5V 0V 0.5V 0V GDH i n high impedance state Figure 7. SC2447 Overload Hiccup Operation Timing Diagram 2006 Semtech Corp. Reference Voltage Min.( REF REFSS t10 t11 t12 t13 14 SC2447 www.DataSheet4U.com V SS/EN Enable Hiccup V COMP ...
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... EM interference. Minimum Switch On Time Consideration In the SC2447, the falling edge of the clock turns on the top MOSFET. The inductor current and the sensed voltage ramp up. After the sensed voltage crosses a threshold determined by the error amplifier output, the top MOSFET ...
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... Rosc (k Ohm) Figure 8. Free Running Frequency vs. R Inductor (L) and Ripple Current Both step-down controllers in the SC2447 operate in synchronous continuous-conduction mode (CCM) regardless of the output load. The output inductor selection/design is based on the output DC and transient requirements. Both output current and voltage ripples are reduced with larger inductors but it takes longer to change the inductor current during load transients ...
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... Remark 2: The total equivalent capacitance of the filter }. bank is not simply the sum of all the paralleled capacitors. The total equivalent ESR is not simply the parallel combination of all the individual ESRs either. Instead 17 SC2447 www.DataSheet4U.com . The RMS current ripple rating should also o δ ...
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... It is also important to place the input capacitor close to the MOSFETs on the PC board to reduce trace inductance around the pulse current loop. The RMS value of the capacitor current is approximately has an ESR of in The power dissipated in the input capacitor is then 18 SC2447 www.DataSheet4U.com δ − ...
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... In a multi-phase converter, interleaved switching reduces ripple. The two step-down channels of the SC2447 operate at 180 degrees from each other. If both step-down channels in the SC2447 are connected in parallel, both the input and the output RMS currents will be reduced. ...
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... leads to lower signal- and Note that R of the bias current of the current amplifier in SC2447. b) When the required current limit I remove R and the time constant = 33nF then calculated from s2 ...
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... Setting the Output Voltage The non-inverting inputs of channel 1 and channel 2 error amplifiers are brought out as device pins (Pin 10 and Pin 8). These pins can be tied to the precision 0.5V reference output (Pin 9) of the SC2447. A simple voltage divider (R at top and R o1 voltage. The voltage feedback gain h=0.5/V ...
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... The inner current-loop is unstable (sub-harmonic oscillation) unless the inductor current up-slope is steeper than the inductor current down-slope. For stable operation above 50% duty-cycle, a compensation ramp is added to the sensed-current. In the SC2447 the compensation ramp is approximately V =D*0.4V. ramp 2006 Semtech Corp. ...
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... The followings are suggested for proper layout. Power Stage 1) Separate the power ground from the signal ground. In the SC2447, the power ground PGND should be tied to the source terminal of lower MOSFETs. The signal ground AGND should be tied to the negative terminal of the output capacitor ...
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... POWER MANAGEMENT Typical Application Schematic 2006 Semtech Corp. 24 SC2447 www.DataSheet4U.com www.semtech.com ...
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... POWER MANAGEMENT Typical Application Schematic 2006 Semtech Corp. 25 SC2447 www.DataSheet4U.com www.semtech.com ...
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... SEE DETAIL SIDE VIEW AND - DETERMINED AT DATUM PLANE -H- DIM Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804 26 SC2447 www.DataSheet4U.com DIMENSIONS INCHES MILLIMETERS NOM MAX MIN NOM MAX - - - .047 1. .006 0.05 0.15 - ...