LINEAR Manuals

The LTC ®1433/LTC1434 are monolithic pulse width modulated step-down DC/DC converters. By utilizing current mode switching techniques, they provide excellent AC and DC load and line regulation.

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The LT ®1683 is a switching regulator controller designed to lower conducted and radiated electromagnetic interference (EMI). Ultralow noise and EMI are achieved by controlling the voltage and current slew rates of external N-channel MOSFET switches. Current and voltage slew rates can be independently set to optimize harmonic content of the switching waveforms vs efficiency. The LT1683 can reduce high frequency harmonic power by as much as 40dB with only minor losses in efficiency. The LT1683 utilizes a dual output (push-pull) current mode architecture optimized for low noise topologies. The IC includes gate drivers and all necessary oscillator, control and protection circuitry. Unique error amp cir- cuitry can regulate both positive and negative voltages. The oscillator may be synchronized to an external clock for more accurate placement of switching harmonics. Protection features include gate drive lockout for low VIN, opposite gate lockout, soft-start, output current limit, short-circuit current limiting, gate drive overvoltage clamp and input supply undervoltage lockout.

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The document introduces the features and characteristics of the LTC4244/LTC4244-1 product. The product can control -12V, 3.3V, 5V and 12V power supplies, with a ±14.4V absolute maximum rating, 12VIN and -12VIN input pins have transient voltage tolerance, adjustable foldback current limiting with circuit breaker, local PCI_RST# logic and PRECHARGE output for biasing I/O pins, LTC4244-1 designed for applications without -12V and with 20-lead narrow SSOP package.

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The LTC3455 is a complete power management solution for a variety of portable applications. The device contains two synchronous step-down DC/DC converters, a USB power controller, a full-featured Li-Ion battery charger, a Hot Swap output, a low-battery indicator, and numerous internal protection features.

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LT1302/LT1302-5 Micropower High Output Current Step-Up Adjustable and Fixed 5V DC/DC Converters

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The LT1425 is a monolithic high power switching regulator specifically designed for the isolated flyback topology. No “third winding” or optoisolator is required; the integrated circuit senses the isolated output voltage directly from the primary side flyback waveform. A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. The LT1425 operates with input supply voltages from 3V to 20V and draws only 7mA quiescent current. It can deliver output power up to 6W with no external power devices. By utilizing current mode switching techniques, it provides excellent AC and DC line regulation. The LT1425 has a number of features not found on other switching regulator ICs. Its unique control circuitry can maintain regulation well into discontinuous mode in most applications. Optional load compensation circuitry allows for improved load regulation. An externally activated shutdown mode reduces total supply current to 15µA for standby operation.

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The LT6650 is a micropower, low voltage 400mV reference. Operating with supplies from 1.4V up to 18V, the device draws only 5.6µA typical, making it ideal for low voltage systems as well as handheld instruments and industrial control systems.

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The LTC2436-1 is a 2-channel differential input micropower 16-bit No Latency ∆Σ analog-to-digital converter with an integrated oscillator. It provides 0.5LSB INL and 800nV RMS noise independent of VREF. The two differential channels convert alternately with a channel identification included in the conversion result. It uses delta-sigma technology and provides single conversion settling of the digital filter. Through a single pin, the LTC2436-1 can be configured for better than 87dB input differential mode rejection at 50Hz and 60Hz ±2%, or it can be driven by an external oscillator for a user defined rejection frequency. The internal oscillator requires no external frequency setting components. The converter accepts any external differential reference voltage from 0.1V to VCC for flexible ratiometric and remote sensing measurement configurations. The full-scale differential input range is from –0.5•VREF to 0.5•VREF. The reference common mode voltage, VREFCM, and the input common mode voltage, VINCM, may be independently set anywhere between GND and VCC. The DC common mode input rejection is better than 140dB. The LTC2436-1 communicates through a flexible 3-wire digital interface which is compatible with SPI and MICROWIRE protocols.

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The LTM4605 is a high efficiency switching mode buck-boost power supply from Philips. It operates over an input voltage range of 4.5V to 20V and supports an output voltage range of 0.8V to 16V. The maximum output current is 5A. This product uses a single inductor architecture, and the input voltage can be higher, lower, or equal to the output voltage. The LTM4605 uses a high switching frequency and current mode architecture, which provides a very fast transient response to line and load changes. The product also has overvoltage and foldback current protection. The LTM4605 is available in a small, thermally enhanced 15mm x 15mm x 2.8mm LGA package and is RoHS compliant.

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The data sheet introduces the features and characteristics of LTC1876 high performance triple output switching regulator and step-up regulator. The chip uses dual phase, dual synchronous step-down switching controller, drives all N-channel synchronous power MOSFET stages, and an internal 1A, 36V step-up regulator provides the third output. The chip uses OPTI-LOOP compensation, which optimizes the transient response over a wide range of output capacitance and ESR values. Each controller's RUN/SS pin provides both soft-start and an optional timed, short-circuit shutdown function that can be configured to latch off one or both controllers. Current foldback provides additional short-circuit protection. In an overvoltage condition, the bottom MOSFET is latched on until VOUT returns to normal. The FCB pin can be used to inhibit Burst Mode operation or to enable regulation of a secondary output voltage. The step-up regulator operates at 1.2MHz, allowing the use of tiny low cost capacitors and inductors. In addition, its internal 1A switch allows high current outputs to be generated. Its current mode control scheme provides excellent line and load regulation.

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The LTC1261 is a voltage inverter that can provide a regulated negative voltage from a single positive supply. It features adjustable or fixed output voltages, low output ripple, shutdown mode, and guaranteed output regulation.

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LTC3425 is a synchronous, 4-phase boost converter with output disconnect capable of operation below 1V input. It includes four N-channel MOSFET switches and four P-channel synchronous rectifiers for an effective RDS(ON) of 0.045Ω and 0.05Ω, respectively. 4-phase operation greatly reduces peak inductor currents, and capacitor ripple current, and increases effective switching frequency, minimizing inductor and capacitor sizes. True output disconnect eliminates inrush current and allows zero load current in shutdown. External Schottky diodes are not required.

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The LTC1142/LTC1142L/LTC1142HV are dual synchronous step-down switching regulator controllers featuring automatic Burst Mode™ operation to maintain high efficiencies at low output currents. The devices are composed of two separate regulator blocks, each driving a pair of external complementary power MOSFETs, at switching frequencies up to 250kHz, using a constant off-time current mode architecture providing constant ripple current in the inductor. The operating current level for both regulators is user programmable via an external current sense resistor. Wide input supply range allows operation from 3.5V* to 18V (20V maximum). Constant off-time architecture provides low dropout regulation limited only by the RDS(ON) of the external MOSFET and resistance of the inductor and current sense resistor. The LTC1142 series is ideal for applications requiring dual output voltages with high conversion efficiencies over a wide load current range in a small amount of board space. Dual Outputs: 3.3V and 5V or User Programmable Ultrahigh Efficiency: Over 95% Possible Current Mode Operation for Excellent Line and Load Transient Response High Efficiency Maintained over 3 Decades of Output Current Low Standby Current at Light Loads: 160µA/Output Independent Micropower Shutdown: IQ < 40µA Wide VIN Range

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The LTC®1484 is a low power RS485 compatible transceiver with a fail-safe feature that guarantees a high receiver output state when the inputs are left open, shorted together or terminated with no signal present. The LTC1484 can also drive low cost residential telephone wires.

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The LT1120 is a combination micropower positive regulator and free collector comparator on a single monolithic chip. With only 40µA supply current, the LT1120 can supply over 125mA of output current. Input voltage range is from 4.5V to 36V and dropout voltage is 0.6V at 125mA. Dropout voltage decreases with lower load currents. Also included on the chip is a class B output 2.5V reference that can either source or sink current. A shutdown pin allows logic shutdown of the output. The comparator can be used for system or battery monitoring. For example, the comparator can be used to warn of low system voltage. Frequency compensation of the comparator for amplifier applications can be obtained by adding external output capacitance. The 2.5V reference will source or sink current. This allows it to be used as a supply splitter or auxiliary output.

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The LTC ®1707 is a high efficiency monolithic current mode synchronous buck regulator using a fixed frequency architecture. The operating supply range is from 8.5V down to 2.85V, making it suitable for both single and dual lithium-ion battery-powered applications. Burst Mode op- eration provides high efficiency at low load currents. 100% duty cycle provides low dropout operation, extend- ing operating time in battery-powered systems. The switching frequency is internally set at 350kHz, allowing the use of small surface mount inductors. For noise sensitive applications it can be externally synchro- nized up to 550kHz. Burst Mode operation is inhibited during synchronization or when the SYNC/MODE pin is pulled low preventing low frequency ripple from interfer- ing with audio circuitry. Soft-start is provided by an external capacitor. The internal synchronous MOSFET switch increases effi- ciency and eliminates the need for an external Schottky diode, saving components and board space.

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The LTC3718 is a 1.5V input voltage, synchronous buck/boost controller, for DDR/QDR memory termination. It features low input voltage, fast transient response, high efficiency, true current mode control and more.

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Low-voltage single supply op amps LT1881/LT1882 feature high accuracy input performance and RRO output swing.

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The LTC3719 is a 2-phase, VID programmable, synchronous step-down switching regulator controller that drives two N-channel external power MOSFET stages in a fixed frequency architecture. The 2-phase controller drives its two output stages out of phase at frequencies up to 300kHz to minimize the RMS ripple currents in both input and output capacitors. The 2-phase technique effectively multiplies the fundamental frequency by two, improving transient response while operating each channel at an optimum frequency for efficiency. Thermal design is also simplified. An operating mode select pin (FCB) can be used to select among three modes including Burst Mode operation for highest efficiency. An internal differential amplifier provides true remote sensing of the regulated supply’s positive and negative output terminals as required in high current applications. The RUN/SS pin provides soft-start and optional timed, short-circuit shutdown. Current foldback limits MOSFET dissipation during short-circuit conditions when the overcurrent latchoff is disabled. OPTI-LOOP compensation allows the transient response to be optimized for a wide range of output capacitors and ESR values. 2-Phase, High Efficiency, Step-Down Controller for AMD Opteron CPUs.

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The LT1004 is a 2-terminal bandgap reference diode designed to provide high accuracy and excellent temperature characteristics at very low operating currents. It has an initial accuracy of ±4mV, an operating current of 10µA, and can operate up to 20mA.

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