Power Electronics / Power Management


Voltage conversion at low energy levels

24 November 2021 Power Electronics / Power Management

Conversion efficiency is a key characteristic of power converters. Common switching regulators for step-down conversion (buck converters) typically have conversion efficiencies of between 85% and 95%. The efficiency to be reached strongly depends on the available supply voltage and the respective output voltage to be generated, as well as the required load current. However, numerous applications require a special type of conversion efficiency for which there are special switching regulator solutions. These deployments require optimised converters for low output power.

Battery-operated systems that are always on often need to consume a very low amount of current in standby mode. Examples include sensors that measure vibrations in bridges or that detect forest fires. In these cases, it is important to have a low battery discharge over long periods of time. This property is particularly important in systems that depend on energy harvesters as energy sources.

Such sensors are frequently also connected via radio to other devices. Individual node points that are usually supplied through energy harvesting or with batteries are linked to transmit signals across several node points and over long distances. These individual radio nodes must always listen for signals in a type of ‘sleep mode’ and then, when a corresponding signal occurs, switch to an operating mode with a higher energy consumption and propagate the corresponding signals.

A new class of DC-to-DC converters has been introduced with the LTC3336. While the output voltage is generated and there is a low load at the output, it only consumes about 65 nA of current in standby mode. Figure 2 shows a compact example circuit that generates an output voltage of 2,5 V from a VIN of approximately 7 V.

As is usual with such voltage converters, the output voltage is not set via a resistor voltage divider. This would waste too much energy. To allow different output voltages to be set, the pins OUT0 to OUT3 are used. Depending on the wiring of these pins, the output voltage can be set in steps between 1,2 V and 5 V.

In many energy harvesting applications, the energy source must be protected from excessive current loads. Some batteries or harvesters can only deliver a limited amount of current. If this specific current limit is exceeded, the voltage sags or, in some cases, damage can even occur. Therefore, it makes sense to limit the current draw of the power converter. The LTC3336 can limit the input current in adjustable steps between 10 mA and 300 mA. This input current limitation is similar to the output voltage in that it can be set through appropriate wiring of the IPK0 and IPK1 pins.

The efficiency plot in Figure 3 shows the efficiencies that can be reached with very low output currents such as 1 µA. A lot of energy is saved, especially in applications with long operating times and low loads.

Conclusion

The LTC3336 is the perfect choice for battery-powered systems since it draws only 65&nbs;nA of current when in standby mode. This means that circuits with fixed battery sizes can be operated for a much longer time, or energy harvesters can be designed to be smaller and therefore lower-cost.


Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Microchip expands its mSiC solutions
EBV Electrolink Power Electronics / Power Management
The highly integrated 3,3 kV XIFM plug-and-play digital gate driver is designed to work out-of-the-box with high-voltage SiC-based power modules to simplify and speed system integration.

Read more...
LoRaWAN-certified sub-GHz module
Altron Arrow Telecoms, Datacoms, Wireless, IoT
The STM32WL5M from ST Microelectronics is the company’s first LoRaWAN-certified module which incorporates two cores, one of them being a wireless stack to optimise the creation of sub-GHz applications.

Read more...
Dual-port USB-C power delivery solution
Altron Arrow Power Electronics / Power Management
Infineon’s CYPD7272-68LQXQ is the tray packing option of the company’s dual-port USB-C power delivery solution and features an integrated dual-port USB-C PD + DC-DC controller.

Read more...
Ryzen V3000 computer on module
Altron Arrow Computer/Embedded Technology
SolidRun has recently announced the launch of its new Ryzen V3000 CX7 Com module, configurable with the eight-core/16-thread Ryzen Embedded V3C48 processor.

Read more...
Parallel redundancy power module
Conical Technologies Power Electronics / Power Management
The LIR40-40 is a wide input range DC-DC module, with a constant output of 48 V at a nominal output current of up to 40 A.

Read more...
Motor protection relay front-end
NewElec Pretoria Power Electronics / Power Management
Newelec’s Motor Protection Relay front-end software isn’t just another tool, it’s a game changer that puts control firmly in your hands.

Read more...
High-power three-phase supplies
Current Automation Power Electronics / Power Management
The units from Meanwell can either be supplied with a three-phase three-wire delta input of 196 to 305 V AC, or they can use a three-phase four-wire star connection of 340 to 530 V AC.

Read more...
Collab between Arrow and Infineon
Altron Arrow News
Arrow Electronics, represented by Altron Arrow in South Africa, and its engineering services company, eInfochips, are working with Infineon Technologies to help eInfochip’s customers accelerate the development of EV chargers.

Read more...
Make your small asset tracker last longer
Altron Arrow Editor's Choice Power Electronics / Power Management
This design solution reviews a typical asset tracking solution, and shows how the MAX3864x nanopower buck converter family, with its high efficiency and small size, enables longer battery life in small portables.

Read more...
Multiprotocol wireless SoC
Altron Arrow DSP, Micros & Memory
The EFR32MG24 Wireless SoCs are ideal for mesh IoT wireless connectivity using Matter, OpenThread, and Zigbee protocols for smart home, lighting, and building automation products.

Read more...