Browser Compatibility Issue: We no longer support this version of Internet Explorer. For optimal site performance we recommend you update your browser to the latest version. However, engineers often unknowingly refer to these topologies by the wrong name, adding confusion to an pump it up application pdf that already is a bit confusing.
Why choose one topology over the other? The Ćuk topology can typically be obtained from a device that also provides a boost, SEPIC or flyback topology. The high voltage, low quiescent current LT8331 is an example of a device that can be configured as a Ćuk converter. 5V to 100V input voltage range and includes a 140V, 0. The coupling or blocking capacitor receives energy from the input side of the circuit and transfers it to the output side of the circuit. A variation of the Ćuk converter circuit is the inverting charge pump circuit where inductor L2 is replaced by Schottky diode D3 shown below. The LT3581 is a multitpology switching regulator with a 3.
In figure 3 and figure 4, the Ćuk converter and the inverting charge pump converter topologies are shown side-by-side for comparison. Cuk’s second inductor has been replaced by a Schottky diode. The lowside switch is also used in boost, SEPIC and flyback topologies, so these devices are quite versatile. The switch node always has a positive voltage applied to it. The Cuk can be used when the magnitude of VOUT is greater than or less than VIN. Figure 5a shows the Ćuk current flow with the power switch closed and figure 5b show the Ćuk current flow with the power switch open. The current in both inductors decreases when the switch opens.
Continuous current flow combined with the LC filters results in a smoother input and output current, which in turn gives low output voltage ripple noise. For a Ćuk, this voltage is always positive. One cannot simply take a Ćuk converter and configure it as a single inductor inverter to reduce circuit components. The inverting charge pump is closely related to a step-up converter because it combines an inductor-based step-up regulator with an inverting charge pump. Note in the figure 5a Ćuk circuit that the circuitry and current flow in the left most portion of the figure is identical to a boost converter.
To this circuitry we add diodes and capacitors to obtain the inverting charge pump converter. Though it uses a charge pump, fairly high load currents can be obtained because the inductor is the main energy storage element rather than a flying capacitor. Output disconnect is inherently built into this single inductor topology. C2 when the switch turns on. An example of the single inductor inverting topology is shown in figure 9 below using the LTC3863 inverting controller with external power switch. Let’s look at the current flow during switching cycles for each topology.