by Petre Petrov @ electronicdesign.com:
The bipolar NE555 timer IC is widely used in inductorless dc-dc converters, most frequently in doubling and inverting converters. However, another very popular IC, the LM386 audio amplifier, may be a better solution in this application. Note that the results also depend on the specific manufacturer of these multisourced ICs and on the quality of the related components. (We will use only Schottky diodes, to reduce the voltage losses to the minimum.)
Comparing the NE555 Timer and LM386 Amplifier as Inductorless DC-DC Converters - [Link]
by DAVID BURGOON @ edn.com:
There are several ways to produce a negative voltage from a positive voltage source, including using a transformer or two inductors and/or multiple switches. However, none are as easy as using the LTC3863, which is elegant in its simplicity, has superior efficiency at light loads and reduces parts count compared to alternative solutions.
The LTC3863 can produce a –0.4V to –150V negative output voltage from a positive input range of 3.5V to 60V. It uses a single-inductor topology with one active P-channel MOSFET switch and one diode. The high level of integration yields a simple, low parts-count solution.
AppNote: Inverting DC/DC controller converts a positive input to a negative output with a single inductor - [Link]
The LT3042 is an ultralow noise, ultrahigh power supply ripple rejection (PSRR) low dropout voltage linear regulator. Its unique design features ultralow spot noise of only 2nV/√Hz at 10kHz and 0.8μV integrated output noise across a wide 10Hz to 100kHz bandwidth. Low frequency PSRR exceeds 90dB out to 10kHz and high frequency PSRR exceeds 75dB out to 3MHz, quieting noisy or high ripple input supplies. The LT3042 delivers up to 200mA output current with a 350mV dropout voltage at full load, across a wide 1.8V to 20V input voltage range. The LT3042 utilizes LTC’s proprietary LDO architecture – a precision current source reference followed by a high performance unity gain buffer, resulting in virtually constant bandwidth, noise, PSRR and load regulation performance independent of output voltage. In addition, this architecture permits paralleling of multiple LT3042s to further decrease noise, increase output current and spread heat on a printed circuit board (PCB).
LTC3402 – 2A, 3MHz Micropower Synchronous Boost Converter - [Link]
PMP9194 uses the TPS54020 synchronous-buck SWIFT converter with integrated FETs to provide a 10A/1V solution in less than 22mmx12mm of total board space area. This reference design uses a small 1.1uH inductor, 2x100uF ceramic output capacitors, and small 0402 external components to save space. The device switches at 300kHz and acheives 87% peak efficiency from a 12V input to a 1V output. The TPS54020 is ideal for powering low-voltage, high-current DSPs and FPGAs, and can be synchronized 180 degrees out-of-phase with another TPS54020 to reduce input ripple.
4.5V to 17V Input, 10-A Synchronous Buck Converter Optimized for Small Size and Low Output Voltage - [Link]
MILPITAS, CA February 5, 2015 Linear Technology announces the LTC7138, a 140V inputcapable high efficiency buck converter that delivers up to 400mA of continuous output current. It operates from an input voltage range of 4V to 140V, making it ideal for a wide range of telecom, industrial, avionic and automotive applications. The LTC7138 utilizes a programmable hysteretic mode design to optimize efficiency over a broad range of output currents. It utilizes an internal 1.8 Ohm power MOSFET for robust, high efficiency operation. A user programmable output current limit can set output current from 100mA to 400mA as required by the particular application. The LTC7138 can be programmed with fixed output voltages of 1.8V, 3.3V or 5V, or a resistor divider can be used to program outputs from 0.8V to V . The LTC7138’s thermally enhanced MSOP offers additional pin spacing required for high voltage inputs. The combination of its MSOP and only four tiny externals provides a highly compact solution footprint for a wide array of applications.
LTC7138 – High Efficiency, 140V 400mA Step-Down Regulator - [Link]
By Chris Glaser @ ti.com:
Especially for switch-mode power supplies (SMPSs), the printed circuit board (PCB) layout is a critical but often under appreciated step in achieving proper performance and reliability. Errors in the PCB layout cause a variety of misbehaviors including poor output voltage regulation, switching jitter, and even device failure. Issues like these should be avoided at all costs, since fixing them usually requires a PCB design modification. However, these pitfalls are easily circumvented if time and thought are spent during the PCB layout process before the first PCBs are ever ordered. This article presents five simple steps to ensure that your next step-down converter’s PCB layout is robust and ready for prototyping.
Five steps to a great PCB layout for a step-down converter - [Link]
by Steve Taranovich @ edn.com:
Linear Technology Corporation just announced another in its series of power management ICs for automotive usage, the LT8640, a 5A, 42V input capable synchronous step-down switching regulator. A unique Silent Switcher™ architecture, combined with spread spectrum frequency modulation, reduces EMI/EMC emissions by more than 25dB even with switching frequencies in excess of 2MHz, enabling it to easily pass the automotive CISPR25, Class 5 peak limits. This feature varies the clock with a triangular frequency modulation of +20%.
Silent Switcher with high efficiency and low EMI/EMC - [Link]
by Susan Nordyk @ edn.com:
A synchronous PWM controller for negative-to-negative or negative-to-positive DC/DC conversion, the LT8709 from Linear Technology is easily configured for buck, boost, buck-boost, and inverting topologies to accommodate a wide range of power-supply designs. The device’s synchronous operation means that the output diode is replaced with a high-efficiency P-channel MOSFET, increasing efficiency and allowing for higher output currents of up to 20 A. It also eliminates the heat sink typically required in medium- to high-power applications.
The LT8709 operates over an input range of -4.5 V to -80 V and produces an output from -0.1 V to as high as 60 V or from -1.4 V to as low as -80 V. Its rail-to-rail output-current monitor and control enable the device to be configured as a current source. The controller has an EN/FBIN pin that accepts slowly varying input signals, as well as an adjustable undervoltage lockout function.
Buck/boost/inverting controller delivers up to 20 A - [Link]
Linear Technology announces the LT3790, a synchronous buck-boost DC/DC controller that delivers up to 250 W of power with a single IC. Its 4.7 V to 60 V input voltage range makes it ideal for a wide variety of automotive and industrial applications. Its output voltage can be set from 0 V to 60 V, making it well suited as a voltage regulator or battery/supercapacitor charger. The LT3790’s internal 4-switch buck-boost controller operates from input voltages above, below or equal to the output voltage, making it ideal for applications such as automotive, where the input voltage can vary dramatically during stop/start, cold crank and load dump scenarios. Transitions between buck, pass-through and boost operating modes are seamless, offering a well regulated output in spite of wide variations of supply voltage. The LT3790’s unique design utilizes three control loops to monitor input current, output current and output voltage to deliver optimal performance and reliability.
60V, Synchronous Buck-Boost Controller - [Link]
Intersil have introduced a single chip just 9 x 6.5 mm which contains just about all the control features (including the output stages) needed to build a dual 0.8 to 5 V power supply with 3 A per channel output capability. The ISL8203M can also supply 6 A in current sharing operation.
The ISL8203M is an integrated step-down power module optimized for generating low output voltages down to 0.8V. The input supply voltage range spans from 2.85 V to 6 V. The two channels are clocked 180° out-of-phase to help reduce input RMS current and EMI. While in current sharing mode this interleaving of the two channels is beneficial for reducing input and output voltage ripple.
Dual 3A PSU on a Chip - [Link]