sc4524a Semtech Corporation, sc4524a Datasheet
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sc4524a
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sc4524a Summary of contents
Page 1
... SC4524A 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 SC4524A is available in SOIC-8 EDP package. SS270 REV 1N4148 ...
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... Pin SOIC - EDP) Marking Information yyww=Date code (Example: 0752) xxxxx=Semtech Lot No. (Example: E900) Ordering Information Device SC4524ASETRT BST SC4524AEVB FB Notes: COMP () 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. Package ...
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... 0.8V 0.8V FB COMP V = .2V 0.8V FB COMP (Note ) I = -2.6A SW SC4524A ……………………………… 36°C/W () ………………………………… 5.5°C/W () Min Typ Max Units 3 28 2.70 2.82 2.95 ...
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Electrical Characteristics (Cont.) Unless otherwise noted 2V 5V 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 SC4524A 5 ...
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... PWM PWM - - R R CLK CLK OSCILLATOR OSCILLATOR 1.23V 1.23V + + - - R R SOFT-START SOFT-START AND AND 1.9V 1.9V OVERLOAD OVERLOAD HICCUP HICCUP FAULT FAULT CONTROL CONTROL Figure 2. SC4524A Block Diagram - - 1.9V 1. 1V/2.15V 1V/2.15V 3.5mA 3.5mA SC4524A ISEN ISEN - - 6.1mW 6.1mW + + ...
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... IN 100 10 ( 0.5 1 1.5 Frequency (MHz) Switch Saturation Voltage vs Switch Current 300 250 200 o - 125 150 100 50 0.0 0.5 1.0 1.5 Switch Current (A) (3) SC4524A Efficiency (6) 1MHz =20BQ030 1 0.5 Load Current (A) SS270 REV 6-7 Frequency vs Temperature 1.2 R =93.1k OSC 1.1 1.0 R =12.1k OSC 0 ...
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... Soft-Start Voltage 2.5 o 125 C 2.0 o -40 C 1.5 1.0 0.5 (15) 0.0 0 0.5 1 1 Shutdown Threshold vs Temperature IN 0.40 0.35 0.30 0.25 0.20 -50 - Temperature ( C) SC4524A SS270 REV 6-7 V Shutdown Current 100 - (V) IN SS270 REV 6-7 Soft-Start Charging Current vs Soft-Start Voltage 0.0 -0.5 -1.0 o 125 C -1.5 -2.0 -2.5 -3.0 ...
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... When the SS/EN pin is released, the soft-start capacitor is charged with an internal .6µA current source (not shown in Figure 3). As the SS/EN voltage exceeds 0.4V, the internal bias circuit of the SC4524A turns on and the SC4524A draws 2mA from V turns off and the 2µA current source I charges the soft-start capacitor. ...
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... V Setting the Switching Frequency = = − − CESAT CESAT The switching frequency of the SC4524A is set with an external resistor from the ROSC pin to ground ⋅ ⋅ − − ...
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... ⋅ D ⋅ ⋅ ⋅ CESAT CESAT The peak current limit of SC4524A power transistor least 2.6A. The maximum deliverable load current for the ⋅ ...
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... Inc.), SS3, SS23 (Vishay), CMSH-40M, CMSH- 40ML and CMSH2-40M (Central-Semi.) are all suitable. The freewheeling diode should be placed close to the SW pin of the SC4524A on the PCB to minimize ringing due to trace inductance. Bootstrapping the Power Transistor The typical minimum BST-SW voltage required to fully saturate the power transistor is shown in Figure 5, which is about ...
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... buck converter with the SC4524A. The inner loop (current loop) consists of a current sensing resistor ( and a current amplifier (CA) with gain ( − − ...
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... operation, the size of the loop formed by these components . C should be minimized. Since the power switch is already , to cancel the ESR zero, integrated within the SC4524A, connecting the anode ≈ ≈ ω ω the freewheeling diode close to the negative terminal of ...
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... SC4524A , for common input and output The compensator Recommended Parameters R7(k) C5(nF) C8(pF) 4.32 2.2 12.4 1.0 15 0.82 20 0.68 43.2 0.47 20 0.68 10 43.2 0.47 35.7 0.68 63.4 0.47 35.7 0.68 63.4 0.47 43.2 ...
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... C4 C1 4.7mF 0.1mF BST IN SW SC4524A SS/EN FB COMP ROSC GND 10nF C8 13.0k 23.7k 22pF C5 2.2nF L1: Coiltronics DR73-8R2 C2: Murata GRM31CR60J226M C4: Murata GRM32ER71H475K 800kHz 10V-26V to 3.3V/2A Step-Down Converter L1 OUT 8.2mH 1.5V/2A R4 33. 20BQ030 66.5k 22mF D1 1N4148 L1 OUT 8.2mH 3.3V/2A R4 3.65k SS23 1.58k 22mF SC4524A 6 ...
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Typical Performance Characteristics (For A 24V to 5V/2A Step-down Converter with 1MHz Switching Frequency) SS270 REV 6-7 Load Characteristic 0.5 1 1.5 Load Current (A) Figure 12(a). Load Characteristic 5V Output Response ...
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... SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE. Semtech Corporation Power Mangement Products Division 200 Flynn Road, Camarillo, CA 9302 Phone: (805) 498-2 Fax: (805) 498-3804 SC4524A DIMENSIONS INCHES MILLIMETERS DIM MIN MAX ...