by Steve Taranovich @ edn.com:
A circuit or system designer’s job is a difficult one. Fraught with design compromises to be made and challenges to overcome that are sometimes seemingly insurmountable. That’s why our personalities are programmed to solve problems and “Think outside the box”. The best designers don’t even know there is a box!
I see so many new product offerings every day that “fill a hole in our line” or are simply another op amp or regulator for the portfolio among a sea of analog and power devices out there. I turn away the great majority of these so-called “new” products because my readers need innovative solutions with options that can meet their many and varied design needs. Time to market is the mantra in the industry.
Power management for wearables: Designer options - [Link]
by Steven Keeping @ digikey.com
Switching DC-to-DC voltage converters (“regulators”) comprise two elements: A controller and a power stage. The power stage incorporates the switching elements and converts the input voltage to the desired output. The controller supervises the switching operation to regulate the output voltage. The two are linked by a feedback loop that compares the actual output voltage with the desired output to derive the error voltage.
The controller is key to the stability and precision of the power supply, and virtually every design uses a pulse-width modulation (PWM) technique for regulation. There are two main methods of generating the PWM signal: Voltage-mode control and current-mode control. Voltage-mode control came first, but its disadvantages––such as slow response to load variations and loop gain that varied with input voltage––encouraged engineers to develop the alternative current-based method.
Today, engineers can select from a wide range of power modules using either control technique. These products incorporate technology to overcome the major deficiencies of the previous generation.
This article describes voltage- and current-mode control technique for PWM-signal generation in switching-voltage regulators and explains where each application is best suited.
Voltage- and Current-Mode Control for PWM Signal Generation in DC-to-DC Switching Regulators - [Link]
Adding to their ever growing family of power supply regulators Linear Technology have introduced the LTC3807 step-down switching regulator DC/DC controller driving an all N-channel external synchronous power MOSFET stage. The chip uses a constant frequency current mode architecture allowing a phase-lockable frequency of up to 750 kHz.
The chip draws just 50 μA no-load quiescent current and an OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3807 features a precision 0.8 V reference and power-good output indicator.
Low-loss Step-down Regulator - [Link]
Ken Shirriff has a great post on his blog about reverse engineering how a 7805 voltage regulator works:
Under a microscope, a silicon chip is a mysterious world with puzzling shapes and meandering lines zigzagging around, as in the magnified image of a 7805 voltage regulator below. But if you study the chip closely, you can identify the transistors, resistors, diodes, and capacitors that make it work and even understand how these components function together. This article explains how the 7805 voltage regulator works, all the way down to how the transistors on the silicon operate. And while exploring the chip, I discovered that it is probably counterfeit.
Reverse Engineering A Counterfeit 7805 Voltage Regulator - [Link]
This project has been designed around Texas Instruments LM2623 IC, The LM2623 is a high efficiency, general purpose step-up DC-DC switching regulator for battery powered and low input voltage systems. It accepts an input voltage between 2.4V to 12V volts and coverts it into 5V DC. Efficiencies up to 90% are achievable with the LM2623.
2.4V to 5V Step Up DC-DC Converter - [Link]
To add to its growing family of voltage regulator solutions Linear Technology Corporation have announced the LT3061, a high-voltage, low-noise, low-dropout voltage linear regulator with active output discharge. The device can deliver up to 100 mA of continuous output current with a 250 mV dropout voltage at full load. The LT3061 features an NMOS pull-down that discharges the output when SHDN or IN is driven low. This rapid output discharge is useful for applications requiring power conditioning on both start-up and shutdown (e.g. high-end imaging sensors).
A single external capacitor provides programmable low noise reference performance and output soft-start functionality. The LT3061 has a quiescent current of 45μA and provides fast transient response with a minimum 3.3μF output capacitor. In shutdown the quiescent current is less than 3μA and the reference soft-start capacitor is reset.
A High Voltage LDO regulator - [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]
Just when you thought all new voltage regulator chips were using switched-mode technology along comes X-REL semiconductor with a linear design. The company specializes in manufacturing high-reliability, high-temperature devices; its XTRM prefixed components have an operational temperature range from −60 to +230ºC.
The recently announced XTR70010 Ultra Low Drop Out linear regulator has a dropout voltage of just 0.9 V per Amp of output current at 230ºC. It operates with an input voltage between 2.8 and 5.5 V and can supply more than 1.5 A with no requirement on the minimum dropout at lower current. The output voltage can be defined with a resolution of 100 mV between 0.5 to 3.6 V (a total of 32 levels) using internal settings or by using a conventional external voltage divider network.
Novel ULDO Linear Regulator - [Link]
By Ashok Bindra:
The use of low-dropout regulators, popularly known as LDOs, is common in many applications today because they provide a simple and inexpensive way to regulate an output voltage that is stepped-down from a higher input voltage. In addition, linear LDO voltage regulators contribute very-low noise as compared to switching regulators.
Nonetheless, to keep system power consumption low, such regulators must also feature ultra-low quiescent current (IQ) while providing excellent dynamic performance to ensure a stable, noise-free voltage rail, suitable for driving IC loads such as microprocessors, FPGAs, and other devices on the system board.
Selecting the Right Ultra-Low Quiescent-Current LDO Regulator - [Link]