SC4508AMLTRT Semtech, SC4508AMLTRT Datasheet
SC4508AMLTRT
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SC4508AMLTRT Summary of contents
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... WEEE and RoHS compliant Applications Low power point of use converters Single or multiple output low power converters Positive and/or negative output voltage DSL cards Graphic cards I/O cards Negative bias supplies Vin V+ VREF FB+ SC4508A FB- COMP Vout SS/EN GND OSC 1 SC4508A CS OUT Vout www.semtech.com ...
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... Note: (1) Voltage from internal circuitry could be higher than 3.2V. See Application Information, Soft-Start section. Electrical Characteristics Unless specified 12V FB+ REF 2007 Semtech Corp OUT = open 1uF, C FB- VDD SS/ SC4508A 0.1uF 330pF -40°C to 125°C OSC www.semtech.com ° ° ° C ° C ° ...
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... POWER MANAGEMENT Electrical Characteristics (Cont.) Unless specified 12V FB+ REF FB 2007 Semtech Corp OUT = open 1uF 0.1uF, C VDD SS/ ° > < SC4508A = 330pF -40°C to 125°C OSC www.semtech.com µ ...
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... TOP VIEW VDD OSC COMP OUT SS/ VREF NC AGND (MLPQ - 12, 4mm x 4mm) Pin Descriptions 2007 Semtech Corp. Ordering Information Notes: 9 FB+ (1) Only available in tape and reel packaging. A reel contains 3000 devices. 8 FB- (2) Lead free product. This product is fully WEEE and RoHS compliant. 7 PGND ...
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... POWER MANAGEMENT Block Diagram Marking Information Top View yyww = Date Code (Example: 0012) 2007 Semtech Corp. 5 SC4508A www.semtech.com ...
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... The free-running frequency of the internal oscillator can be programmed with an external capacitor from the OSC pin to the ground. The SC4508A controller is capable of 2007 Semtech Corp. operating up to 1.5 MHz necessary to consider the operating duty-ratio before deciding the switching frequency. Minimum Switch On Time Consideration In the SC4508A the falling edge of the clock turns on the MOSFET ...
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... The overload latch is reset when the SS/EN capacitor is discharged below 0.5V. The SS/EN capacitor is then recharged with the 10µA current source and the converter 2007 Semtech Corp. undergoes soft-start. If overload persists, the SC4508A will undergo repetitive auto-shutdown-restart hiccup mode. ...
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... The output capacitor can be modeled as an ideal capacitor in series with its parasitic ESR (R ESL (L ) (Figure 1). esl 2007 Semtech Corp. = *Idc, the the current through the branch is i across the terminals will then be: ...
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... ESR and improve high frequency decoupling. Because the values of capacitance and ESR are usually different in ceramic and aluminum capacitors, 2007 Semtech Corp. the following remarks are made to clarify some practical issues. Remark 1: High frequency ceramic capacitors may not carry most of the ripple current ...
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... Figure 4. Figure 4. Typical waveforms at converter input. 2007 Semtech Corp. It can be seen that the current in the input capacitor pulses with high di/dt. Capacitors with low ESL should be used also important to place the input capacitor close to the MOSFETs on the PC board to reduce trace inductances around the pulse current loop ...
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... R varies with temperature and gate-source voltage. ds(on) Curves showing R variations can be found in ds(on) 2007 Semtech Corp. manufacturers’ data sheet. From the FDS6675 datasheet, R than 10V. However R junction temperature increases from 25 The switching losses can be estimated using the simple formula: ...
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... MOSFET and loss freewheeling diode are known, thermal and package design at component and system level should be done to verify that the maximum die junction temperature 2007 Semtech Corp usually 125 j,max case condition. The equivalent thermal impedance from junction to ambient ( ...
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... As a result, there will be a set error in the converter output voltage. This non-random error is caused by the feedback voltage divider ratio. It cannot be corrected by the feedback loop. The following table lists a few standard resistor combinations for realizing some commonly used output voltages. 2007 Semtech Corp ...
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... Voltage Setting” section with: 2007 Semtech Corp. For the rated output current fixed as: From Figure 7, the transfer function from the voltage error amplifier output (v ...
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... further calculated that oesr o 134 use C = 120pF. The Bode plot of the loop transfer 3 function (magnitude and phase) is shown in Figure 8. 2007 Semtech Corp. ( ⋅ 20 log =300kHz, C =100uF 180 arg π 57 Figure 8. The loop transfer function Bode plot of the buck example. ...
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... and 2007 Semtech Corp. The loop transfer function is then To simplify design, we assume that C With these assumptions, the controller zero is placed at the converter dominant pole, the controller second pole is placed at the converter ESR zero or RHP zero depending on whichever is lower. The DC gain is finally adjusted for desired phase margin ...
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... In some initial prototypes, if the circuit noise makes the control loop jitter suggested to use a bigger C than the calculated one here. Effectively, the converter 2007 Semtech Corp. bandwidth is reduced in order to reject some high frequency noises. In the final working circuit, the loop k transfer function should be measured using network analyzer and compared with the design to ensure circuit stability under different line and load conditions ...
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... VDD SS/EN OUT OSC VREF 0.1uF FB+ 330pF 6 8 AGND FB- f s=470KHz 7 10 PGND COMP Bill of Materials 2007 Semtech Corp 47uF/16V 47uF/16V 10K C3 0. TP1 U2 FDFS2P102A TP3 TP2 0.1uF 1 8 TP4 R4 20K C10 2nF C11 2.7nF TP5 TP6 SC4508A L1 10uH 5V/ 470uF/6.3V 470uF/6. ...
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... SC4508A C4 1uF 12 VDD 3 SS/ OSC 0.1uF 680pF 6 AGND f s=250KHz 7 PGND Bill of Materials 2007 Semtech Corp. TP9 10K C3 0.06 1nF R2 100 TP1 TP10 Si4831DY 1 4 OUT 4 3 VREF FB+ 0.1uF 8 1 FB- TP4 10 COMP R4 20K C10 100pF C8 C11 47uF/16V 2.7nF TP5 TP6 TP7 TP8 ...
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... Buck Overcurrent Protection Buck Overcurrent Protection Buck Overcurrent Protection 10mS/DIV a: OUT PIN VOLTAGE, 10V/DIV b: SS/EN PIN VOLTAGE, 1V/DIV c: INDUCTOR CURRENT, 2A/DIV 2007 Semtech Corp. Buck-Boost Converter Startup Buck-Boost Converter Startup Buck-Boost Converter Startup Buck-Boost Converter Startup Buck-Boost Converter Startup 5mS/DIV a: OUTPUT VOLTAGE, 5V/DIV ...
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... PIN 1 INDICATOR (LASER MARK) A aaa C E1 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS. Land Pattern - MLPQ-12 (C) NOTES: 1. Contact Information Phone: (805)498-2111 FAX (805)498-3804 2007 Semtech Corp. DIM MIN .031 A1 .000 - A2 b .010 D .153 E D1 ...