I explain buck converters (a type of switch mode power supply) and how to build a 5V 5A power supply using an LM2678.
How to build a switch mode power supply! DC-DC buck converter tutorial! - [Link]
by BABU TA @ edn.com:
This flasher/beacon circuit can be employed as a distress signal on highways, a direction pointer for parking lots, hospitals, and hotels, etc. The circuit uses a power LED, and provides more light than a typical incandescent lamp flasher. Use of a 6V or 12V SLA lantern battery makes the circuit portable.
HB-LED flashing beacon repurposes switching regulator - [Link]
Linear Technology has recently announced an addition to its family of power regulator solutions. The LTC3622 is a dual step-down regulator in a small 3 x 4 mm package providing two independently configurable 1 A outputs operating from a 2.7 to 17 V input. External voltage divider networks define the two output voltages or alternatively a range of fixed output voltage versions result in a lower component count. The input voltage range makes it suitable for operation from single or multiple lithium cells or from a vehicular supply.
New Dual step-down Regulator - [Link]
TI’s TPS43061 is a low IQ current-mode synchronous boost controller with wide input voltage range from 4.5V to 38V, boosted output range up to 58V, operates over an extended junction temperature range of -40 to 150°C and includes an integrated boot diode and a 5.5V gate-drive optimized to reduce switching loss with lower Qg NexFET™ technology.
TPS43061 – Small-Size, High-Efficiency, Low-lQ Synchronous Boost Controller - [Link]
by sajjad Haidar @ edn.com:
Power supplies with adjustable DC output ranging from 0V to 30V or 60V are on the market. Above 60V, there are not many. This Design Idea offers a solution.
There are many fixed voltage switching mode power supplies (SMPS) available, and connecting several in series can give us a higher fixed voltage. To obtain an adjustable output either from a SMPS or conventional transformer based supply, one needs to use a linear regulator or a switched mode buck converter. For a buck converter, a MOSFET or an IGBT can be used as a switching element.
Usually, for a high side switch, an IC with bootsrap operation or a pulse transformer is used. There are few photovoltaic couplers available to drive MOSFETs. As they do not provide much current to charge the gate capacitance quickly, these photovoltaic couplers are mainly used to drive low frequency MOSFET switches, such as solid state relays.
Variable HV power supply employs photovoltaic optocoupler - [Link]
Linear Technology Corp have introduced the LTC3124 which is a two phase 3 MHz current-mode synchronous boost DC/DC converter featuring output disconnect and inrush current limiting. Dual phase operation has the benefit of reducing peak inductor and capacitor ripple currents allowing equivalent performance to be achieved in the power supply design with smaller valued inductors and capacitors.
The LTC3124 incorporates low resistance MOSFETs with an RDS(ON) of 130mΩ (N-channel) and 200mΩ (P-channel) to deliver efficiencies as high as 95%. The output disconnect feature allows the output to be completely discharged at shutdown and reduces switch-on inrush. An input pin can be used to configure the LTC3124 for continuous frequency mode to give low-noise operation. Additional features include external synchronization, output overvoltage protection, and robust short-circuit protection.
Dual-Phase Boosts Step-Up Efficiency - [Link]
Switch-mode regulator Traco TSR 0.5 will give you as much as you need. If you have an application, where 0.5A is sufficient, then the new series of DC/DC modules is ideal for you.
Maybe, it´s worth to ask a question, whether it makes sense to use a switch-mode regulator for such a low current? For sure yes, at least because of two reasons. If we need to create 3.3V from for example 12V, then at a current of 0.5A a power loss of 4.35W appears at a classic linear regulator. That´s already a quite considerable power, able to heat up a device – especially at smaller enclosures and a dense population on a PCB.
Another reason is energy saving – especially at battery powered devices. Switch mode power supplies (SMPS) have a “genial” feature, that thanks to their high efficiency we use practically whole power drawn from a source, i.e. if we need say 5V/0.5A from a 15V source – we won´t take from it 0.5A but only approx. 0,17-0,18A.
Novelty of company Traco Electronic – series TSR 0.5 is by its function very similar to well known, proven DC/DC regulators TSR1 or TSRN1. The main difference is in a smaller allowed current and a feelingly lower price . That ´s why this series is very suitable for any application, where a current of 0.5A will be sufficient. A big advantage can be a wide operating temperatures range from -40 to +90°C (power derating 5%/K at temperature above 80°C). Maximum input voltage of 32V enables a usage even at power supplying from various alternative energy sources with a big input voltage fluctuations.
This novelty is so far available in a version with 5V output voltage (TSR 0.5-2450) and soon there will be another.
Why to pay for the current, which you won’ t use? - [Link]
By Steven Keeping @ digikey.com:
Modular DC-DC switching voltage converters (or voltage regulators) are fully integrated devices that take away most of the complexity of power supply design — but not all. One of the key areas that are still left to the design engineer’s discretion is the choice of components for, and layout of, the energy storage and filtering circuits. In principle, these look like simple circuits comprising a few resistors, capacitors, and the energy-storage element, usually an inductor.
Capacitor Selection is Key to Good Voltage Regulator Design - [Link]
An SMPS application using PIC16F785 from Microchip. [via]
In this application note, we will examine a typical buck topology intelligent SMPS design using the PIC16F785.
The design presented here shows an alternative single-chip approach to adding intelligence to SMPS designs. The basic design is really unchanged. There are current and voltage feedback loops, a counter-based PWM is used to generate the reference voltage to the voltage loop, and the microcontroller uses the reference voltage to modify the operation of the system in response to conditions sensed through the ADC.
App note: Switching power supply design with the PIC16F785 - [Link]
TPS54361-Q1 4.5-V to 60-V Input, 3.5-A, Step Down DC-DC Converter with Soft-Start and Eco-mode™. by ti.com:
The TPS54361-Q1 device is a 60-V, 3.5-A, step down regulator with an integrated high side MOSFET. The device survives load dump pulses up to 65 V per ISO 7637. Current mode control provides simple external compensation and flexible component selection. A low ripple pulse skip mode and supply current of 152-µA enables high efficiency at light loads. Shutdown supply current is reduced to 2 μA when the enable pin is pulled low.
Undervoltage lockout is internally set at 4.3 V but can increase using an external resistor divider at the enable pin. The output voltage startup ramp is controlled by the soft start pin that can also be configured for sequencing/tracking. An open-drain power-good signal indicates the output is within 93% to 106% of the nominal voltage.
TPS54361-Q1 – 4.5-V to 60-V Input, 3.5-A, Step Down DC-DC Converter with Soft-Start - [Link]