sc4508a Semtech Corporation, sc4508a Datasheet
sc4508a
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sc4508a Summary of contents
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... POWER MANAGEMENT Description The SC4508A is a low voltage current mode switching regulator controller that drives a P-channel power MOSFET with programmable switching frequency. It can be configured in either buck or buck boost (inverting) con- verters. The converters can be operated from 2.7V to 15V input voltage range. The typical operating supply ...
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... SC4508A 0.1uF 330pF ...
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... SC4508A = 330pF -40°C to 125°C OSC ...
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... SC4508A ...
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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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... MOSFET is turned off. The propagation delay time from the turn-on of the controlling MOSFET to its turn-off is the minimum switch on time. The SC4508A has a minimum on time of about 180ns at room temperature. This is the shortest on interval of the controlling PFET. The controller either does not turn on the MOSFET at all or turns it on for at least 80ns ...
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... If the CS pin senses 32 consective switching cycles of over current, the SC4508A will shut down and hold off the MOSFET while discharging the soft-start capacitor. The SS/EN capacitor is discharged with an internal 12mA current sink ...
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... Aluminum capacitors (e.g. electrolytic, solid OS-CON, POSCAP, tantalum) have high capacitances and low ESL’s. The ESR has the dominant effect on the output ripple voltage therefore very important to minimize the ESR. ) and esr 8 SC4508A Co Lesl Resr Figure 1. An equivalent circuit of C (t), the voltage b t ...
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... ESRs either. Instead they should be calculated using the following formulae where R electrolytic capacitors, and R capacitance of the ceramic capacitors respectively. (Figure SC4508A ceramic capacitor ...
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... MOSFETs are directly related to the total gate charge ( order to judge the performance of MOSFETs, ds(on) the product of the total gate charge and on-resistance is used as a figure of merit (FOM). Transistors with the same FOM follow the same curve in Figure 5. 10 SC4508A ...
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... R gt rail to the gate of the MOSFET. It includes the gate driver internal impedance R gate resistance the Miller plateau voltage shown in Figure 11. gsp Similarly an approximate expression for t 11 SC4508A is less than 14m when V ds(on) increases by 30% as the ds(on 110 ...
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... The time taken to charge the capacitor from 0. The time to charge the capacitor from 0.9V to 1.4V (driver is enabled but output duty cycle SC4508A C) is not exceeded under the worst should satisfy max , a ...
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... R Loop Compensation SC4508A is a current-mode controller. Current-mode . Since the control is a dual-loop control system in which the inductor o peak current is loosely controlled by the inner current- loop ...
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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 SC4508A the compensation ramp is made switching frequency dependent. The slope of the compensation ramp is: S ...
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... For buck-boost converter, a simplified equivalent circuit model of the buck converter with current mode control is shown in Figure 9 and the transfer function from the voltage error amplifier output ( is SC4508A 100 100 76.67 53. 6.67 16.67 − 100 ...
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... For example D=0.51, C calculate that is: c ω Set = 500, the controller parameters then can calculated as where, g (100 µ use C 16 SC4508A T(s)=G (s)G (s <<C 3 ω ...
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... Maximize the trace width of the loop connecting the inductor, PFET and the output capacitors. 9. Connect the ground of the feedback divider and the compensation components directly to the AGND pin of the SC4508A by using a separate ground trace. Then connect this pin to the ground of the output capacitor as close as possible. value ...
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... SC4508A L1 10uH 5V/ 470uF/6.3V 470uF/6.3V R5 18.0K R6 2.0K TP7 TP8 ...
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... SC4508A C1 C2 47uF/16V 47uF/16V 5 TP3 33uH -5V/0.5A C9 100uF/6.3V R5 4.99K GND R6 499 ...
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... Buck-Boost DCM Operation 500nS/DIV a: OUT PIN VOLTAGE, 10V/DIV b: PHASE NODE VOLTAGE, 10V/DIV c: INDUCTOR CURRENT, 1A/DIV Buck-Boost Overcurrent Protection Buck-Boost Overcurrent Protection Buck-Boost Overcurrent Protection Buck-Boost Overcurrent Protection Buck-Boost Overcurrent Protection 10mS/DIV a: OUT PIN VOLTAGE, 10V/DIV b: SS/EN PIN VOLTAGE, 1V/DIV c: INDUCTOR CURRENT, 2A/DIV 20 SC4508A www.semtech.com ...
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... THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 21 SC4508A DIMENSIONS INCHES MILLIMETERS NOM MAX MIN NOM MAX - - .040 ...