sc4525c Semtech Corporation, sc4525c Datasheet
sc4525c
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sc4525c Summary of contents
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... SC4525C achieves fast transient response with simple loop compensation. Cycle-by-cycle current limiting and hiccup overload protection reduces power dissipation during output overload. Soft-start function reduces input start- up current and prevents the output from overshooting during power-up. The SC4525C is available in SOIC-8 EDP package. SC4525A D1 1N4148 C1 0.33mF ...
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... Pin SOIC - EDP) Marking Information yyww=Date code (Example: 0752) xxxxx=Semtech Lot No. (Example: E9010) Ordering Information Device SC4525CSETRT BST SC4525CEVB FB Notes: COMP (1) Available in tape and reel only. A reel contains 2,500 devices. (2) Available in lead-free package only. Device is fully WEEE and RoHS SS/EN compliant and halogen-free. ...
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... 0.8V 0.8V FB COMP V = 1.2V 0.8V FB COMP (Note -3.9A SW SC4525C ……………………………… 36°C/W (1) ………………………………… 5.5°C/W (1) Min Typ Max Units 3 28 2.70 2.82 2.95 225 2 2 ...
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Electrical Characteristics (Cont.) Unless otherwise noted 12V 15V BST Parameter Minimum Switch On-time Minimum Switch Off-time Switch Leakage Current Minimum Bootstrap Voltage BST Pin Current Oscillator Switching Frequency Foldback Frequency Soft Start and Overload ...
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... V The exposed pad serves as a thermal contact to the circuit board soldered to the ground plane of the 9 Exposed Pad PC board. falls below 0.8V, then the switching frequency will be reduced order to fully enhance the internal NPN power transistor. IN SC4525C 5 ...
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... SS/EN SS/EN FAULT FAULT Figure 3. Soft-start and Overload Hiccup Control Circuit SLOPE + COMP PWM CLK 1.2V R SOFT - START AND OVERLOAD HICCUP FAULT CONTROL Figure 2. SC4525C Block Diagram - - 1.9V 1. 2.4mA 2.4mA B1 B1 1V/2.15V 1V/2.15V 3.9mA 3.9mA ISEN - 3.53m W ...
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Eff Typical Characteristics Efficiency =3. =2. =1. 1MHz, V =12V Curve =B320A 0.5 ...
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... Temperature ( SS270 REV 6-7 V Shutdown Current 100 - 1.5 2 SS270 REV 6-7 Soft-Start Charging Current vs Soft-Start Voltage 0.0 -0.5 -1.0 125 -1.5 -2.0 -2.5 -3 100 125 0 0 SC4525C 125 ( - 1 ( ...
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... When the SS/EN pin is released, the soft-start capacitor is charged with an internal 1.9µA current source (not shown in Figure 3). As the SS/EN voltage exceeds 0.4V, the internal bias circuit of the SC4525C turns on and the SC4525C draws 2mA from V turns off and the 2.4µA current source I charges the soft-start capacitor. ...
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... CESAT CESAT The switching frequency of the SC4525C is set with an external resistor from the ROSC pin to ground. Table 3 lists the standard resistor values for typical frequency setting ⋅ ⋅ − − ...
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... SC4525C is 3.9A minus one half of the inductor ripple current Input Decoupling Capacitor L L The input capacitor should be chosen to handle the RMS ripple current of a buck converter. This value is given The input capacitance must also be high enough to keep input ripple voltage within specification ...
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... Rectifier), B320A, B330A (Diodes Inc.), SS33 (Vishay), CMSH3-20MA and CMSH3-40MA (Central-Semi.) are all suitable. The freewheeling diode should be placed close to the SW pin of the SC4525C on the PCB to minimize ringing due to trace inductance. Bootstrapping the Power Transistor The minimum BST-SW voltage required to fully saturate the power transistor is shown in Figure 5, which is about 2V at room temperature ...
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... COMP COMP Figure 7. Block diagram of control loops The block diagram in Figure 7 shows the control loops of a buck converter with the SC4525C. The inner loop (current C1 loop) consists of a current sensing resistor (R ...
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... C Thermal Considerations ⋅ ⋅ ( For the power transistor inside the SC4525C, the between 10% and conduction loss ω ω ...
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... TOTAL TOTAL BST BST The temperature rise of the SC4525C is the product of the = = ⋅ ⋅ ⋅ ⋅ CESAT CESAT O O total power dissipation (Equation (12)) and q which is the thermal impedance from junction to ambient ...
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... Fsw(kHz) C2(uF) L1(uH) 500 3.3 500 4.7 1000 2.2 500 6.8 1000 3.3 47 500 6.8 1000 3.3 500 6.8 1000 3.3 500 3.3 300 6.8 500 6.8 500 6.8 1000 3.3 500 47 8.2 1000 4.7 500 10 1000 4.7 500 15 SC4525C , for common input and output The compensator Recommended Parameters R7(k) C5(nF) C8(pF) Snubber 5.23 3.9 8.45 3.9 15.4 0.82 12.1 3.9 20.5 0.82 no 15.4 3.9 36.5 0.82 22.6 3.9 47.5 0.82 36.5 3.9 22 3.57 3.9 6.49 3.9 12.1 3.9 1 +220pF 22 ...
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Typical Application Schematics 24V 4.7mF Coiltronics DR74- 6R8 Figure 10. 300kHz 24V to 1.5V/3A Step-down Converter 10V – 26V 4.7m F Fig10 : 300 kHz 1.5V/3 ...
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... Inductor Current (1A/DIV) 40us/DIV Figure 12(c). Load Transient Response (I = 0. 3.5 4 4.5 OCP Figure 12(d). Output Short Circuit (Hiccup) 12V Input (5V/DIV) 5V Output (2V/DIV) SS Voltage (1V/DIV) 10ms/DIV Figure 12(b). V Start up Transient ( Output Short (5V/DIV) Retry Inductor Current (2A/DIV) SS Voltage (2V/DIV) 20ms/DIV SC4525C =3A ...
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... DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. REFERENCE JEDEC STD MS -012, VARIATION BA e bxN bbb C A SEE DETAIL SIDE VIEW - DETERMINED AT DATUM PLANE SC4525C DIMENSIONS INCHES MILLIMETERS DIM MIN NOM MAX MIN NOM - - .053 .069 1. .000 .005 0. ...
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... REFERENCE IPC-SM-782A, RLP NO. 300A. 3. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE. E SOLDER MASK D DIM SC4525C DIMENSIONS INCHES MILLIMETERS (.205) (5.20 .134 3.40 E .201 5.10 F ...
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... Semtech products for any such unauthorized application, the customer shall indemnify and hold Semtech and its officers, em- ployees, subsidiaries, affiliates, and distributors harmless against all claims, costs damages and attorney fees which could arise. Contact Information Semtech Corporation Power Mangement Products Division 200 Flynn Road, Camarillo, CA 93012 ...