Publitek European Editors writes:
Many security and motion detector systems rely on small, semi-autonomous nodes that are easy and simple to install. This implies the use of a battery-based power source and low-power operation in order to minimize the number of battery changes during the lifetime of the product.
Over its lifetime, the output voltage of a battery falls, with the biggest decline when the charge is nearing full depletion. A converter type that can accommodate this change in voltage but can still provide relatively high voltages for sensors and RF transmitters is the buck-boost converter – it operates the buck part of the circuit when the battery is fresh, moving to boost operation when the voltage falls below the threshold of the electronic circuitry it powers. A number of vendors have developed integrated buck-boost converters optimized for battery systems
Buck-Boost Converters Help Extend Battery Life for Motion Detection - [Link]
Steve Taranovich writes:
Linear Technology Corporation announced the LT8705, a very high efficiency (up to 98%) synchronous buck-boost DC/DC controller that operates from input voltages above, below or equal to the regulated output voltage. This device has four feedback loops to regulate the input current/voltage, along with the output current/voltage.
Convert any input voltage from 2.8V to 80V into a fixed output voltage or output current - [Link]
Jason Frels wrote an excellent article on his experience working with LTC3731 based switchmode power supply. The article is focused on stability testing and performance tweak of the power supply. To test the stability of a control loop we have to measure the frequency where the gain is 0dB and the phase margin on that point. For a stable design the phase margin should be 45° or better. Also the frequency on 0dB point shouldn’t be to low (even with good phase margin) as this drives to slow response of output on load changes. To make such measurements specialized equipment is used. Check the great graphs on the link below.
Stability Testing a Switching Mode Power Supply - [Link]
Giorgos @ PCBheaven build a MCP1640 boost converter for the next LED light project. This converter can be used with almost dead batteries and will squeeze any remaining energy from them. [via]
What i want now, is something to spice up this hack. So here is what – I used the MCP1640 boost converter to drain the last electron from the batteries. This chip can work with a ridiculous low voltage and provide enough power to drive a couple LEDs. Which means the 2 AA batteries will operate even longer and the LEDs will be much brighter.
High efficiency battery boost regulator using the MCP1640 - [Link]
The LTM4641 is a 4.5V to 38V input, 0.6V to 6V output, 10A step-down μModule regulator with comprehensive input and load protection features. The part monitors input voltage, output voltage and temperature conditions. If any user-adjustable trip thresholds are exceeded, the LTM4641 responds quickly (within 500ns in the case of an output overvoltage fault), ceasing operation and if necessary activating external switches to protect both input source and load. As a μModule regulator, the LTM4641 includes power MOSFETs, DC/DC controller, inductor, compensation and the protection logic circuits in a compact surface mount BGA package.
- Wide Operating Input Voltage Range: 4.5V to 38V
- 10A DC Typical, 12A Peak Output Current
- Output Range: 0.6V to 6V
- ±1.5% Maximum Total Output DC Voltage Error
- Differential Remote Sense Amplifier for POL Regulation
- Internal Temperature, Analog Indicator Output
LTM4641 – 38V, 10A DC/DC µModule Regulator with Advanced Input and Load Protection - [Link]
by Publitek European Editors:
Small, flexible, low-cost but high-performance microcontrollers, and the off-the-shelf boards built around them, are revolutionizing the world of electronics design for small systems. Products such as the Microchip PIC16, the Atmel AVR and Texas Instruments MSP430, and ready-made modules based around these and similar microcontrollers such as the Arduino and Basic Stamp, provide a range of flexible, programmable I/Os that lend themselves to a wide variety of different applications.
Many of these systems are powered by batteries, which have a strongly variable output voltage as they discharge. For example, the voltage output by a rechargeable lithium-ion battery will typically fall as it discharges from 4.2 V to around 3 V, with a wide plateau in the 3.5 V region. This is where most of the stored power will be delivered.
Flexible Power for Versatile Micros - [Link]
The LT®3651-8.2/LT3651-8.4 are 2-cell, 4A Li-Ion/Polymer battery chargers that operate over a 9V to 32V input voltage range. An efficient monolithic average current mode synchronous switching regulator provides constant current, constant voltage charging with programmable maximum charge current. A charging cycle starts with battery insertion or when the battery voltage drops 2.5% below the float voltage. Charger termination is selectable as either charge current or internal safety timer timeout. Charge current termination occurs when the charge current falls to one-tenth the programmed maximum current (C/10). Timer based termination is typically set to three hours and is user programmable (charging continues below C/10 until timeout).
LT3651-8.2 and 8.4 – Monolithic 4A High Voltage 2-Cell Li-Ion Battery Charger – [Link]
SKL14 can be used in switch-mode power supplies or as protection diodes and thanks their really miniature dimensions, they are also suitable at the lack of PCB space.
SMT Technologies enable a substantial increase of current density thanks to a very good heat transfer from a component to a PCB. Almost a zero length of „leads“ of SMT components also features another positive aspects like a significant suppression of a parasitic inductancy and a possibility to construct circuits with a high components density and a minimal PCB tracks length, what significantly decreases an undesired radiation (EMI) for example in switch-mode power supplies.
A very small forward voltage drop <0.55V/1A and the speed of Schottky diodes make the SKL14 a universal diode suitable for example for rectifying, for SMPS or as a reverse polarity protection diode. A relatively high current is mainly enabled by a Power SOD-123 package with enhanced thermal properties.
SKL14 – 1A Schottky diode will fit everywhere - [Link]
The TPS92510 by Texas Instruments is a 1.5-A constant current DC/DC buck converter with a combo of frequency synchronization, pulse-width modulation (PWM) dimming and thermal foldback firsts. Used with the WEBENCH LED Architect, users rapidly design a power management circuit to drive a string of up to 17 high-brightness LEDs at up to 97% power efficiency in automotive, industrial, and general lighting applications.
The TPS92510 operates with fixed frequency by using its internally generated clock or via synchronization to an external PWM clock source. Thermal foldback ensures light output remains even in an LED over-temperature condition, adding safety. [via]
- 3.5-V to 60-V input voltage operating range supports a wide variety of DC LED lighting applications, including area and street lighting.
- Fixed switching frequency range from 100 kHz to 2.5 MHz can be synchronized to optimize for efficiency or solution size.
- LED thermal foldback with external negative temperature coefficient (NTC) protects LED array from over-temperature while maintaining reduced light output.
- Dedicated PWM dimming input from 100 Hz to 1 kHz adjusts LED brightness without color shift or perceivable flicker.
Buck converter drives high-brightness LEDs - [Link]
Carolyn Mathas writes:
The LT3763 by Linear Technology is a synchronous buck LED driver controller that delivers more than 300W of LED power. With an input voltage range of 6V to 60V, it targets such applications as automotive, industrial and architectural lighting. Output voltage from 0V to 55V enables it to driver LEDs in a single string. The driver features input and output current monitors and limiting and accurate input and output voltage regulation.
Buck LED driver delivers 300W of power - [Link]