Analog Devices

The LTC1909-8 is a synchronous step-down switching regulator controller with a digitally programmable output voltage. The output voltage is selected from one of two 5-bit settings programmed into internal registers via a 2-wire SMBus/I²C interface. The interface features safeguards against invalid output voltages and allows the microprocessor to turn the regulator on and off. Valley current control delivers very low duty cycles without requiring a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in VINand VOUT.Discontinuous mode operation provides high efficiency operation at light loads. A forced continuous control pin reduces noise and RF interference and can assist secondary winding regulation by disabling discontinuous mode operation when the main output is lightly loaded.Fault protection is provided by internal foldback current limiting, an output overvoltage comparator and optional short-circuit shutdown timer.The LTC1909-8 is available in the 28-lead SSOP package.ApplicationsPower Supplies for DSPs, ASICs, FPGAs and CPUsVoltage Margining

The LTC1911 is a switched capacitor step-down DC/DC converter that produces a 1.5V or 1.8V regulated output from a 2.7V to 5.5V input. The part uses switched capacitor fractional conversion to achieve high efficiency over the entire input range. No inductors are required. Internal circuitry controls the step-down conversion ratio to optimize efficiency as the input voltage and load conditions vary. Typical efficiency is over 25% higher than that of a linear regulator.A unique constant frequency architecture provides a low noise regulated output as well as lower input noise than conventional charge pump regulators. High frequency operation (fOSC= 1.5MHz) simplifies output filtering to further reduce conducted noise. To optimize efficiency,the part enters Burst Mode®operation under light load conditions.Low operating current (180µA with no load, 10µA in shutdown) and low external parts count (two 1µF flying capacitors and two 10µF bypass capacitors) make the LTC1911 ideally suited for space constrained battery powered applications. The part is short-circuit and over temperature protected, and is available in an 8-pin MSOP package.ApplicationsHandheld ComputersCellular PhonesSmart Card ReadersPortable Electronic EquipmentHandheld Medical InstrumentsLow Power DSP Supplies

The LTC1921 monitors two independent –48V supplies, including their fuses, and drives up to three optoisolators to indicate status, in accordance with standard backplane specifications. Requiring only three noncritical resistors and optoisolators, the LTC1921 replaces multiple voltage comparators, a voltage reference and several precision resistors.The monitor features dual supply overvoltage and undervoltage detection circuits. The preset trip thresholds include overvoltage, undervoltage and undervoltage recovery that are guaranteed over temperature and meet or exceed common backplane specifications. Additional built-in circuitry detects the condition of supply fuses. Overvoltage and undervoltage detectors ignore fast supply transients, eliminating false detection. The LTC1921 operates from –10V to –80V with a typical power dissipation of less than 10mW.The LTC1921 is available in 8-pin MSOP and SOIC packages.ApplicationsTelecom Backplanes or Switch CardsNetworking Backplanes or Switch CardsHigh Voltage Fuse Monitoring

The LTC1922-1 phase shift PWM controller provides all of the control and protection functions necessary to implement a high performance, zero voltage switched, phase shift, full-bridge power converter with synchronous rectification. The part is ideal for developing isolated, low voltage, high current outputs from a high voltage input source. The LTC1922-1 combines the benefits of the full-bridge topology with fixed frequency, zero voltage switching operation (ZVS). Adaptive ZVS circuity controls the turn-on signals for each MOSFET independent of internal and external component tolerances for optimal performance.The LTC1922-1 also provides secondary side synchronous rectifier control. The device uses peak current mode control with programmable slope comp and leading edge blanking.The LTC1922-1 features extremely low operating and start-up currents to simplify off-line start-up and bias circuitry. The LTC1922-1 also includes a full range of protection features and is available in 20-pin through hole (N) and surface mount (G) packages.ApplicationsTelecommunications, Infrastructure Power SystemsDistributed Power ArchitecturesServer Power SuppliesHigh Density Power Modules

The LTC1923 is a pulse width modulator intended for thermoelectric cooler (TEC) or heater applications requiring either unidirectional or bidirectional drive circuits. All of the necessary control circuitry and two sets of complementary output drivers are integrated into the LTC1923 to drive a full bridge, providing an efficient means of bidirectional current flow to the TEC. An accurate temperature control loop to stabilize the temperature of a laser diode system is easily achieved with the addition of just a few external components. Typical temperature setpoint accuracy of 0.1°C is achievable with the LTC1923. Adding an instrumentation amplifier front end allows setpoint stability of 0.01°C.The part features independent adjustable heating and cooling pulse-by-pulse current limit, current soft-start for controlled start-up, output slew rate control to reduce system noise, differential current sense and voltage amplifiers and a host of auxiliary circuits to protect the laser and provide redundant system monitoring.ApplicationsLaser-Based Fiber Optic LinksMedical InstrumentsCPU Temperature Regulators

The LTC1929/LTC1929-PG are 2-phase, single output, synchronous step-down current mode switching regulator controllers that drive N-channel external power MOSFET stages in a phase-lockable fixed frequency architecture. The 2-phase controllers drive their 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 internal differential amplifier provides true remote sensing of the regulated supply’s positive and negative output terminals as required by high current applications.The RUN/SS pin provides soft-start and a defeatable, timed, latched short-circuit shutdown to shut down both channels. Internal foldback current limit provides protection for the external synchronous MOSFETs in the event of an output fault. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values.ApplicationsDesktop ComputersInternet/Network ServersLarge Memory ArraysDC Power Distribution Systems

The LTC1955 provides all necessary supervisory and power control functions for two smart cards, two S.A.M. cards or a combination of S.A.M. and smart cards. It provides a charge pump for battery-powered applications as well as all necessary level shifting circuitry.The card voltages can be independently set to 1.8V, 3V or 5V. Both card interfaces include a card detection channel with automatic debounce circuitry. To reduce wiring costs, the LTC1955 interfaces to a microcontroller via a simple 4-wire serial interface. Multiple devices may be connected in daisychain fashion so that the number of wires to the card socket board is independent of the number of sockets. Status data is returned over the same interface.Extensive security features ensure proper deactivation sequencing in the event of a supply fault or a smart card electrical fault. The smart card pins can withstand greater than 10kV ESD in-situ with no additional components.The LTC1955 is available in a low profile (0.75mm) 5mm × 5mm QFN package.ApplicationsHandheld Payment TerminalsPay TelephonesATM MachinesPOS TerminalsComputer KeyboardsMultiple S.A.M. Sockets

The LTC1960 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 automatically 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 consuming minimum PCB area.ApplicationsPortable ComputersPortable Instruments

The LTC1966 is a true RMS-to-DC converter that utilizes an innovative patented ∆Σ computational technique. The internal delta sigma circuitry of the LTC1966 makes it simpler to use, more accurate, lower power and dramatically more flexible than conventional log antilog RMS-to-DC converters.The LTC1966 accepts single-ended or differential input signals (for EMI/RFI rejection) and supports crest factors up to 4. Common mode input range is rail-to-rail. Differential input range is 1VPEAK, and offers unprecedented linearity. Unlike previously available RMS-to-DC converters, the superior linearity of the LTC1966 allows hassle free system calibration at any input voltage.The LTC1966 also has a rail-to-rail output with a separate output reference pin providing flexible level shifting. The LTC1966 operates on a single power supply from 2.7V to 5.5V or dual supplies up to ±5.5V. A low power shutdown mode reduces supply current to 0.5μA.The LTC1966 is insensitive to PC board soldering and stresses, as well as operating temperature. The LTC1966 is packaged in the space saving MSOP package which is ideal for portable applications.ApplicationsTrue RMS Digital Multimeters and Panel MetersTrue RMS AC + DC Measurements