You may have already had an application, where it would have been suitable to use a switched power supply, but when you saw a datasheet, you rather used a classic proven linear stabilizer. With the integrated circuit L5973D it is possible to design in a short time a reliable and powerful power source, at a low cost.
Switch-mode power supplies (SMPS) are being more and more used because of their undoubted advantage – much higher efficiency than classic linear stabilisers. In contrast to linear power supplies, SMPS-es have almost the same efficiency at various input/otput voltage ratios, which uses to be 80-95%. That´s why, if we need a much lower output voltage, than input voltage (e.g. 5V from 24V), an SMPS still has a very good efficiency, unlike almost catastrophic 20% at linear stabiliser. For many applications, the best solution is to use a ready-made DC/DC module or to use switch-mode stabilisers which directly replace stabilisers of 78xx series. However, for many applications a solution from discrete components is more suitable. From our offer of switch-mode regulators, we would like to introduce you a perspective circuit L5973D from ST Microelectronics.
L5973D is a switch-mode buck regulator (step down) with the integrated 2.5A output transistor P-FET D-MOS, working at 250kHz frequency, in a HSOP-8 package. Input voltage can be 4-36V and an output voltage can be from 1,235 to 35V. For a construction of power source, only minimum of external components are necessary. Thanks to the integrated output transistor, it is easy to reach an optimal components layout and short power tracks on PCB. That´s why it is much easier to reach a minimum interference (EMI) in comparison to a solution with external switching transistor. L5973D contains a thermal protection, as well as an overcurrent protection, which limits a maximum current in every cycle. Cooling is provided by a thermal pad on the bottom side of the circuit. A big advantage is, thet the circuit is able to work even with the low drop-out (LDO) and the duty cycle 100%, i.e. if the inpout voltage is getting closer to the output voltage (for example a discharging accumulator), L5973D can carry over to the output practically the same voltage as it has on the input (voltage feedforward). This is especially useful at battery applications, when we need to ensure functionality of the device even in critical conditions. Continue reading Switch-mode power supply within few minutes, with the L5973D switched regulator