LINEAR Manuals

The LT1737 is a monolithic switching regulator controller specifically designed for the isolated flyback topology. It drives the gate of an external MOSFET and is generally powered from a DC supply voltage. Output voltage feedback information may be supplied by a variety of methods including a third transformer winding, the primary winding or even direct DC feedback (see Applications Information). Its gate drive capability, coupled with a suitable external MOSFET and other power path components, can deliver load power up to tens of Watts. The LT1737 has a number of features not found on other isolated flyback controller ICs. By utilizing current mode switching techniques, it provides excellent AC and DC line regulation. Its unique control circuitry can maintain regulation well into discontinuous mode in most applications. Optional load compensation circuitry allows for improved load regulation. An optional undervoltage lockout pin halts operation when the application input voltage is too low. An optional external capacitor implements a soft-start function.

The LTC3704 is a wide input range, current mode, positive-to-negative DC/DC controller that drives an N-channel power MOSFET and requires very few external components. Intended for low to high power applications, it eliminates the need for a current sense resistor by utilizing the power MOSFET’s on-resistance, thereby maxi- mizing efficiency.

The LTC6800 is a precision instrumentation amplifier with high CMRR and low input offset voltage. It uses charge balanced sampled data techniques to convert a differential input voltage into a single ended signal, which is then amplified by a zero-drift operational amplifier. The inputs and outputs are both rail-to-rail, making it suitable for applications such as thermocouple amplifiers, electronic scales, medical instrumentation, strain gauge amplifiers, and high resolution data acquisition.

This document introduces the features and characteristics of the LT1086 series products, including 3-terminal adjustable or fixed voltage, 1.5A output current, 1V input-output differential, multiple current levels guaranteed dropout voltage, 0.015% line regulation, 0.1% load regulation, 100% thermal limit functional test,> 75dB ripple rejection, etc.

The LT3750 is a flyback converter designed to rapidly charge large capacitors to a user-adjustable target voltage.

The LT3014 is a high voltage, micropower low dropout linear regulator from National Semiconductor. The device is capable of supplying 20mA of output current with a dropout voltage of 350mV. Designed for use in battery-powered or high voltage systems, the low quiescent current (7µA operating and 1µA in shutdown) makes the LT3014 an ideal choice. Quiescent current is also well controlled in dropout. Other features of the LT3014 include the ability to operate with very small output capacitors. The regulators are stable with only 0.47µF on the output while most older devices require between 10µF and 100µF for stability. Small ceramic capacitors can be used without the necessary addition of ESR as is common with other regulators. Internal protec- tion circuitry includes reverse-battery protection, current limiting, thermal limiting and reverse current protection. The device is available as an adjustable device with a 1.22V reference voltage. The LT3014 regulator is available in the 5-lead ThinSOT and 8-lead DFN packages.

The LTC1873 is a dual switching regulator controller optimized for high efficiency with low input voltages

The LT ®3724 is a DC/DC controller used for medium power, low part count, low cost, high efficiency supplies. It offers a wide 4V-60V input range (7.5V minimum startup voltage) and can implement step-down, step-up, inverting and SEPIC topologies. The LT3724 includes Burst Mode operation, which reduces quiescent current below 100µA.

LTC3901 is an N-channel synchronous MOSFET driver with features such as programmable timeout, reverse inductor current sense, gate drive transformer synchronization sequence monitor, etc. It is designed for use in isolated push-pull and full-bridge converter power supplies. It provides a full range of protection features, including timeout function, inductor current reversal detection, undervoltage lockout, etc.

The LTC3125 is a high effi ciency, synchronous step-up DC/DC converter with an accurate programmable average input current limit. The ±5% accurate average input current is resistor programmable and suitable for a wide variety of applications. In mobile computing, GSM and GPRS cards demand high current pulses well beyond the capability of the PC Card and CompactFlash slots. The LTC3125 in concert with a reservoir capacitor, keeps the slot power safely within its capabilities providing a high performance and simple solution. Synchronous rectifi cation produces high effi ciency while the 1.6MHz switching frequency minimizes the solution footprint. The current mode PWM design is internally com- pensated. Output disconnect allows the load to discharge in shutdown, while also providing inrush current limiting. Other features include a <1μA shutdown current, short- circuit and thermal overload protection. The LTC3125 is of- fered in a low profi le 0.75mm × 2mm × 3mm package.

The LTC ®1960 is a highly integrated battery charger and selector intended for portable products using dual smart batteries. A serial SPI interface allows an external microcontroller to control and monitor status of both batteries. A proprietary PowerPath architecture supports simultaneous charging or discharging of both batteries. Typical battery run times are extended by 10%, while charging times are reduced by up to 50%. The LTC1960 automati cally switches between power sources in less than 10µs to prevent power interruption upon battery or wall adapter removal. The synchronous buck battery charger delivers 95% efficiency with only 0.5V dropout voltage, and prevents audible noise in all operating modes. Patented* input current limiting with 5% accuracy charges batteries in the shortest possible time without overloading the wall adapter. The LTC1960’s 5mm × 7mm 38-pin QFN and 36-pin narrow SSOP packages allow implementation of a complete SBS-compliant dual battery system while consum ing minimum PCB area.

LT1573 is a low cost, high current, low dropout, fast transient response regulator driver IC that can be used with an external PNP power transistor to provide up to 5A of current with a dropout voltage as low as 0.35V. The device is designed for extremely fast transient response. This greatly reduces bulk storage capacitance when the regulator is used in applications with fast, high current load transients. To keep cost and complexity low, the LT1573 uses a new time-delayed latching overcurrent protection technique that requires no external current sense resistor. Base drive is limited for instantaneous protection, and a time-delayed latch protects the regulator from continuous short circuits. The LT1573 is available in both adjustable and fixed versions with a operating voltage range of 2.8V to 10V.

LT6011/LT6012 is a low noise, high precision input performance, low power and wide power supply voltage range op amp, which can be applied to thermocouple amplifiers, precision photodiode amplifiers, instrumentation amplifiers, low voltage precision systems and battery powered precision systems.

The LTC3531/LTC3531-3.3/LTC3531-3 are synchronous buck-boost DC/DC converters that operate from input voltages above, below or equal to the output voltage. The topology incorporated in the ICs provides a continuous transfer through all operating modes, making the product ideal for single cell Li-Ion and multicell alkaline or nickel applications. The converters operate in Burst Mode, minimizing solution footprint and component count as well as providing high conversion efficiency over a wide range of load currents. The devices include two 0.5Ω N-channel MOSFET switches and two P-channel switches (0.5Ω, 0.8Ω). Quiescent current is typically 16μA, making the parts ideal for battery power applications. Other features include a <1μA shutdown current, current limiting, thermal shutdown and output disconnect. The parts are offered in a 6-pin ThinSOTTM package for fixed voltage versions or a 3mm × 3mm DFN package for fixed and adjustable versions.

The LT1934/LT1934-1 is a micropower step-down DC/DC converter with internal 400mA power switch, packaged in a low profile (1mm) ThinSOT. With its wide input range of 3.2V to 34V, the LT1934 can regulate a wide variety of power sources, from 4-cell alkaline batteries and 5V logic rails to unregulated wall transformers and lead-acid batteries. Quiescent current is just 12μA and a zero current shut- down mode disconnects the load from the input source, simplifying power management in battery-powered sys- tems. Burst Mode® operation and the low drop internal power switch result in high efficiency over a broad range of load current. The LT1934 provides up to 300mA of output current. The LT1934-1 has a lower current limit, allowing optimum choice of external components when the required output current is less than 60mA. Fast current limiting protects the LT1934 and external components against shorted outputs, even at 34V input.