Buck-Boost Converter
Calculate the output voltage of a buck-boost DC-DC converter in continuous conduction, V_out = V_in × D ÷ (1 − D), from the input voltage V_in and the duty cycle D (0 to 1). The result, in volts, can be lower (D < 0.5) or higher (D > 0.5) than the input — the buck-boost converter steps voltage down or up depending on the duty cycle, with inverted output polarity in the classic topology. It is used when the input voltage can vary above and below the desired output (discharging batteries, universal supplies). Enter the input voltage and the duty cycle.
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Conversor buck-boost
O conversor buck-boost combina as duas capacidades: pode abaixar ou elevar a tensão, conforme o ciclo de trabalho. Sua relação é V_out = V_in × D ÷ (1 − D). O ponto de virada é D = 0,5: abaixo dele (D < 0,5), a saída é menor que a entrada (modo abaixador); acima (D > 0,5), é maior (modo elevador); em D = 0,5, saída igual à entrada. Na topologia clássica (inversora), a saída tem polaridade invertida em relação à entrada (uma fonte de +12 V produz −V na saída) — daí também ser chamado de conversor inversor; há variantes não inversoras (como o SEPIC e o Ćuk) que mantêm a polaridade. A grande utilidade do buck-boost aparece quando a tensão de entrada varia em torno da tensão de saída desejada — o caso típico de uma bateria: uma bateria de Li-ion vai de ~4,2 V (carregada) a ~3,0 V (descarregada), e se o circuito precisa de 3,3 V estáveis, ora é necessário abaixar (4,2 → 3,3), ora elevar (3,0 → 3,3). Só um conversor que faz as duas coisas resolve, mantendo a saída regulada por toda a descarga da bateria. Por isso o buck-boost (e suas variantes) é comum em dispositivos portáteis alimentados por bateria e em fontes de 'entrada universal'. Informe a tensão de entrada e o ciclo de trabalho.
Related Tools
Buck Converter (Step-Down)
Calculate the output voltage of a buck (step-down) DC-DC converter in continuous conduction, V_out = D × V_in, from the duty cycle D (0 to 1) and the input voltage V_in. The result, in volts, is always less than or equal to the input — the buck converter lowers voltage efficiently (without dissipating the excess, unlike a linear regulator), by switching rapidly and filtering with an inductor and capacitor. Varying the duty cycle adjusts the output from 0 to V_in. It is the most common topology in switching power supplies and point-of-load regulators. Enter the duty cycle and the input voltage.
Boost Converter (Step-Up)
Calculate the output voltage of a boost (step-up) DC-DC converter in continuous conduction, V_out = V_in ÷ (1 − D), from the input voltage V_in and the duty cycle D (0 to 1). The result, in volts, is always greater than the input — the boost converter raises voltage by storing energy in an inductor and releasing it in series with the source. As D approaches 1, the output tends to infinity (limited by real losses). It is used in supplies that must step up voltage (LEDs, batteries, power factor correction) and in photovoltaic systems. Enter the input voltage and the duty cycle.
Output Voltage Ripple
Calculate the output voltage ripple of a switching converter, ΔV = I ÷ (f × C), from the output current I, the switching frequency f and the output capacitance C. The result, in volts, is the residual oscillation superimposed on the DC output voltage, caused by the filter capacitor charging and discharging each switching cycle. Higher frequency and capacitance reduce the ripple. Keeping the ripple within limits (typically <1% of the output) is essential to supply sensitive circuits. Enter the current, the switching frequency and the capacitance.
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