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]
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]
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]
App note(PDF) from NXP on DC-DC medium power small-signal MOSFETs.
This application note explores different methods of DC-to-DC conversion. It includes some examples of DC-to-DC down-converters using small-signal MOSFETs.
App note: Medium power small-signal MOSFETs in DC-to-DC conversion – [Link]
by SparkFun Electronics @ youtube.com:
In today’s episode of “According to Pete,” SparkFun Director of Engineering Pete Dokter is taking a look at homelighting solutions and the SparkFun FemtoBuck LED Driver
SparkFun According to Pete #40: LED Home Lighting and the FemtoBuck Driver – [Link]
Susan Nordyk @ edn.com:
Encapsulated in a tiny 9.0×6.5×1.83-mm QFN package, the ISL8203M step-down DC/DC power module from Intersil furnishes an adjustable output voltage between 0.8 V to 5 V to allow designers to use one device to build a single 6-A or dual 3-A output power supply. The ISL8203M simplifies power-supply design for FPGAs, ASICs, microprocessors, DSPs, and other point-of-load conversions in communications, test and measurement, and industrial systems.
Intersil shrinks step-down DC/DC power module – [Link]
The LTM4625 from Linear Technology is a switching mode μModule (micromodule) regulator in a tiny 6.25 mm × 6.25 mm × 5.01 mm BGA package. Like many of the newer regulator designs, the package includes the switching controller; power FETs, inductor and support components. Operating over an input voltage range of 4 V to 20 V (or 2.375 V to 20 V with an external bias supply) the LTM4625 supports an output voltage range of 0.6 V to 5.5 V, set by a single external resistor. Its high efficiency design delivers up to 5A continuous output current. Only bulk input and output capacitors are needed.
Complete 5A step-down Regulator – [Link]
by Susan Nordyk @ edn.com:
Leveraging Linear Technology’s Silent Switcher architecture and spread- spectrum frequency modulation, the LT8640 synchronous step-down switching regulator reduces EMI/EMC emissions by more than 25 dB—even with switching frequencies in excess of 2 MHz—enabling the part to easily pass automotive CISPR25, Class 5 peak limits. Synchronous rectification achieves efficiency as high as 95% with a switching frequency of 2 MHz, while the part’s 3.4-V to 42-V input range makes it useful for both automotive and industrial applications.
Step-down switching regulator minimizes EMI/EMC – [Link]
The LT®8613 is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator that consumes only 3μA of quiescent current. Top and bottom power switches are included with all necessary circuitry to minimize the need for external components. The built-in current sense amplifier with monitor and control pins allows accurate input or output current regulation and limiting. Low ripple Burst Mode operation enables high efficiency down to very low output currents while keeping the output ripple below 10mVP-P. A SYNC pin allows synchronization to an external clock.
LT8613 – 42V, 6A Synchronous Step-Down Regulator with Current Sense – [Link]