LTC3866 Current Mode Synchronous Controller for Sub Milliohm DCR Sensing - Video Product Brief
with Bruce Haug, Product Marketing Engineer, Power Products

The LTC®3866 is a single phase current mode synchronous step-down switching regulator controller that drives all N-channel power MOSFET switches. It employs a unique architecture which enhances the signal-to-noise ratio of the current sense signal, allowing the use of a very low DC resistance power inductor to maximize the efficiency in high current applications. This feature also reduces the switching jitter commonly found in low DCR applications. The LTC3866 also includes a high speed remote sense differential amplifier, a programmable current sense limit that can be selected to 10mV, 15mV, 20mV, 25mV or 30mV, and DCR temperature compensation to limit the maximum output current precisely over temperature.

The LTC3866 also features a precise 0.6V reference with a guaranteed limit of ±0.5% that provides an accurate output voltage from 0.6V to 3.5V. A 4.5V to 38V input voltage range allows it to support a wide variety of bus voltages and various types of batteries.

The LTC3866 is offered in a low profile 24-lead 4mm × 4mm QFN and 24-lead exposed pad FE packages.

LTspice IV: Evaluating Electrical Quantities
with Gabino Alonso, Strategic Marketing

Utilizing LTspice IV waveform viewer to analyze a circuit and perform basic measurements is very useful. However there are times where you need to evaluate a circuit with a numerical analysis. For these circumstances .MEASURE statements can be very powerful in evaluating user-defined electrical quantities. .MEASURE statements enable measurements like:

• Rise, Fall and Time Delay
• Average, RMS, min, max, and peak-to-peak
• Find X when Y occurs
• Derivative and Integral Evaluations

60V, 98% Efficient, 4-Switch Synchronous Buck-Boost Controller IC Drives LEDs, Regulates Voltage and Charges Batteries
with Keith Szolusha Senior Applications Engineer, Power Products

LEDs are becoming both more popular and more powerful. Strings of 1A, 2A, 3A and higher current LEDs found in vehicles, billboards, industrial lighting, and many more applications need to be driven both accurately and efficiently from DC/DC converters. In many cases, a step-up and step-down topology is needed due to the voltage variation of both the LED string and the input source. In this case, a 4-switch synchronous buck-boost controller is the best solution for its efficiency and small circuit size.

Linear Technology’s LT®3791 is a buck-boost controller IC that drives LED strings from an input voltage up to 60V to an output voltage up to 60V. It can drive over 100W of LEDs at over 98% efficiency. It smoothly transitions from buck region to buck-boost region to boost region as the relationship between input and output voltage changes. LTCs high-end PWM dimming provides accurate and deep brightness control to the LEDs. Short-circuit and open LED string protection and diagnostics make this a robust and highly useful step-up/step-down LED driver.

The LT3791 can operate as both a constant current and constant voltage DC regulator, so it can also be used as an excellent high power buck-boost voltage regulator up to 60V and with short-circuit protection. Both constant current and constant voltage are needed for special sealed lead acid battery chargers and LT3791 has a special 1/10th charger current detection that can be used to switch from a charge voltage to a float voltage for a charged up high power SLA battery.

Matched Resistor Networks for Ultraprecision Applications
with Greg Zimmer Product Marketing Engineer, Signal Conditioning Products

Precision matched resistors are used in a wide range of precision instrumentation applications including measurement and data acquisition, wireless RF, networking, automated test, medical, industrial controls and military equipment.

The LT®5400 is a family of quad, precision matched resistors designed for high performance signal conditioning applications such as difference amplifiers, precision dividers, precision gain stages, and bridge circuits. These thin-film resistors offer outstanding resistor-to-resistor matching and outstanding long term drift, in a small package.

The LT5400 matching is taken one step further with “matching for CMRR,” a new metric that guarantees CMRR performance when configured in a differential circuit. The LT5400’s matching for CMRR is guaranteed to be better than 0.005%, over the full specified temperature range, offering a 2x improvement over resistors matched to within 0.01%.

Achieve 101dB SNR with the LTC2379-18
with Heemin Yang Design Section Leader, Mixed Signal Products

Successive Approximation Register Analog-to-Digital Converters (SAR ADCs) are key components in instrumentation, industrial control, and test equipment applications. The accuracy, noise and speed of the SAR ADC often determine the overall system performance.

Linear Technology’s LTC®2379-18 breaks new ground in SAR ADC technology, achieving 18-bit performance at 1.6Msps with 101dB SNR. In this video presentation, a designer of the LTC2379-18 demonstrates the outstanding performance of the device and shares his insights into the sophisticated design of this 18-bit ADC.

LT3798 Isolated No Opto-Coupler Flyback Controller with Active PFC - Video Product Brief
with Bruce Haug, Product Marketing Engineer, Power Products

The LT®3798 is a constant-voltage/constant-current isolated flyback controller that combines active power factor correction (PFC) with no opto-coupler required for output voltage feedback into a single-stage converter. A LT3798 based design can achieve a power factor of greater than 0.97 by actively modulating the input current, allowing compliance with most Harmonic Current Emission requirements.

The LT3798 is well suited for a wide variety of off-line applications. The input range can be scaled up or down, depending mainly on the choice of external components. Efficiencies higher than 86% can be achieved with output power levels up to 100W. In addition, the LT3798 can easily be designed into high DC input applications.

LTC3765/LTC3766 Isolated Forward Converter Chipset with Active Clamp Reset - Video Product Brief
with Bruce Haug, Product Marketing Engineer, Power Products

The LTC®3765 is a start-up controller and gate driver for use in a self-starting secondary-side control forward converter. When combined with the LTC3766 secondaryside synchronous forward controller, a complete isolated power supply is created using a minimum of discrete parts. A proprietary scheme is used to multiplex gate drive signals and bias power across the isolation barrier through a small pulse transformer. A precision undervoltage lockout circuit and linear regulator controller ensure a quick and well-controlled start-up.

The LTC3766 has been designed to simplify the design of active clamp forward converters. Working in concert with the LTC3765, the LTC3766 forms a robust, self-starting converter that eliminates the need for the separate bias regulator that is commonly used in secondary-side control applications. A precision current-limit coupled with clean start-up into a pre-biased load make the LTC3766 an excellent choice for high-power battery charger applications.

The LTC3766 provides extensive remote sensing and output protection features, while Direct Flux Limit guarantees no transformer saturation without compromising transient response.

LTspice IV: Stepping Parameters
with Gabino Alonso, Strategic Marketing

Plotting voltages or currents in a simulation is important but so is varying a parameter in a device or model so that you can compare performance and develop your circuit intuition. There are two ways to examine a circuit by changing the value of a parameter. You can either manually enter each value then re-simulate the circuit or you can use the .step command to sweep across a range of values in a single simulation run and have a side by side comparison.

This video provides an overview of the basics steps of how to use the .STEP command to perform repeated analysis of a circuit in LTspice IV.

Bob Dobkin Analog Interview
with Bob Dobkin, Vice President, Engineering & Chief Technical Officer

Linear Technology Chief Technical Officer Bob Dobkin discusses analog design challenges and circuit design approaches.

Switching Regulator Power Loss
with Bob Dobkin, Vice President, Engineering & Chief Technical Officer

Efficiency is a misleading number for comparison of switching regulators. The efficiency number can be manipulated by the input and output voltage, while power loss is more tightly tied to the actual circuit. This video explains why.