by Susan Nordyk @ edn.com:
A family of pin-compatible synchronous step-down switching regulators with integrated power switches, the MIC28511/12/13 from Micrel, supplies up to 4 A of output current (MIC28513) and accepts a wide input supply range of 4.6 V to 70 V (MIC28512). The devices have an operating junction temperature range of -40°C to +125°C and come in very small 24-pin, 3×4-mm FCQFN packages.
The MIC28511/12/13 regulators are offered in both Hyper Speed Control and HyperLight Load architectures, which allow for high VIN (low VOUT) operation and fast transient response, while reducing the required output capacitance and providing good light-load efficiency. They furnish an adjustable output voltage as low as 0.8 V with guaranteed accuracy to within ±1%.
High-voltage buck regulators stay cool in tiny packages - [Link]
The LT®3744 is a fixed frequency synchronous step-down DC/DC controller designed to drive a LED load at up to 20A continuous or 40A pulsed. The peak current mode controller will maintain ±3% LED current regulation over a wide output voltage range, from VEE to VIN. By allowing VEE to float to negative voltages, several LEDs in series can be driven from a single Li-Ion battery with a simple, single step-down output stage. PWM dimming is achieved with the PWM pins. The regulated LED current is set with analog voltages at the CTRL pins. Regulated voltage and overvoltage protection are set with a voltage divider from the output to the FB pin. The switching frequency is programmable from 100kHz to 1MHz through an external resistor on the RT pin.
Additional features include an accurate external reference voltage, a control input for thermally derating regulation current, an accurate EN/UVLO pin, an open-drain output fault flag, OVLO, frequency synchronization, and thermal shutdown.
LT3744 – High Current Synchronous Step-Down LED Driver - [Link]
An application note from TI, TPS6122x low input voltage, 0.7V boost converter with 5.5μA quiescent current (PDF!):
The TPS6122x family devices provide a power-supply solution for products powered by either a single-cell, two-cell, or three-cell alkaline, NiCd or NiMH, or one-cell Li-Ion or Li-polymer battery. Possible output currents depend on the input-to-output voltage ratio. The boost converter is based on a hysteretic controller topology using synchronous rectification to obtain maximum efficiency at minimal quiescent currents. The output voltage of the adjustable version can be programmed by an external resistor divider, or is set internally to a fixed output voltage. The converter can be switched off by a featured enable pin. While being switched off, battery drain is minimized. The device is offered in a 6-pin SC-70 package (DCK) measuring 2 mm x 2 mm to enable small circuit layout size.
TPS6122x low input voltage, 0.7V boost converter with 5.5μA quiescent current - [Link]
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]