Analog Devices

The LTC1686/LTC1687 are high speed, precision delay, full-duplex RS485 transceivers that can operate at data rates as high as 52Mbps. The devices also meet the requirements of RS422.A unique architecture provides very stable propagation delays and low skew over a wide common mode and ambient temperature range.The driver and receiver feature three-state outputs, with disabled driver outputs maintaining high impedance over the entire common mode range. A short-circuit feature detects shorted outputs and substantially reduces driver output current. A similar feature also protects the receiver output from short circuits. Thermal shutdown circuitry protects from excessive power dissipation.The receiver has a fail-safe feature that guarantees a high output state when the inputs are shorted or are left floating. The LTC1686/LTC1687 RS485 transceivers guarantee receiver fail-safe operation over the entire common mode range (–7V to 12V). Receiver input resistance remains ≥22k when the device is unpowered or disabled.The LTC1686/LTC1687 operate from a single 5V supply and draw only 7mA of supply current.ApplicationsHigh Speed RS485/RS422 Full Duplex TransceiversLevel TranslatorBackplane TransceiverSTS-1/OC-1 Data TransceiverSignal Repeaters

The LTC1688/LTC1689 are ultrahigh speed, differential bus/line drivers that can operate at data rates up to 100Mbps. Propagation delay is guaranteed at 8ns ±4ns over the full operating temperature range. These devices operate over the full RS485 common mode range (–7V to 12V), and also meet RS422 requirements.The driver outputs are Hot Swap capable, maintaining backplane data integrity during board insertion and removal. The drivers feature three-state outputs, maintaining high impedance over the entire common mode range (–7V to 12V). Outputs also remain high impedance during power-up and with the power off. A short-circuit feature detects bus contention and substantially reduces driver output current. Thermal shutdown circuitry protects the parts from excessive power dissipation.The LTC1688 allows all four drivers to be enabled together, while the LTC1689 allows two drivers at a time to be enabled.The LTC1688/LTC1689 operate from a single 5V or 3V supply and draw only 9mA of supply current.ApplicationsHigh Speed RS485 Twisted-Pair DriversHigh Speed Backplane DriversComplementary Clock DriversSTS-1/OC-1 Data DriversSCSI Drivers

The LTC1693 family drives power N-channel MOSFETs at high speed. The 1.5A peak output current reduces switching losses in MOSFETs with high gate capacitance.The LTC1693-1 contains two noninverting drivers while the LTC1693-2 contains one noninverting and one inverting driver. These dual drivers are electrically isolated and independent. The LTC1693-3 is a single driver with an output polarity select pin.All MOSFET drivers offer VCCindependent CMOS input thresholds with 1.2V of typical hysteresis. They can level-shift the input logic signal up or down to the rail-to-rail VCCdrive for the external MOSFET.The LTC1693 contains an undervoltage lockout circuit and a thermal shutdown circuit that disable the external N-channel MOSFET gate drive when activated.The LTC1693-1 and LTC1693-2 come in an 8-lead SO package. The LTC1693-3 comes in an 8-lead MSOP package.ApplicationsPower SuppliesHigh/Low Side DriversMotor/Relay ControlLine DriversCharge Pumps

The LTC1694-1 is a dual SMBus active pull-up designed to enhance data transmission speed and reliability under all specified SMBus loading conditions. The LTC1694-1 is also compatible with the Philips I2C Bus.The LTC1694-1 allows multiple device connections or a longer, more capacitive interconnect, without compromising slew rates or bus performance, by supplying a high pull-up current of 2.2mA to slew the SMBus or I2C lines during positive bus transitions.During negative transitions or steady DC levels, the LTC1694-1 sources zero current. External resistors, one on each bus line, trigger the LTC1694-1 during positive bus transitions and set the pull-down current level. These resistors determine the slew rate during negative bus transitions and the logic low DC level.The LTC1694-1 is available in a 5-pin SOT-23 package.ApplicationsNotebook and Palmtop ComputersPortable InstrumentsBattery ChargersIndustrial Control ApplicationTV/Video ProductsACPI SMBus Interface

The LTC1695 fan speed controller provides all the functions necessary for a power management microprocessor to regulate the speed of a 5V brushless DC fan via a 2-wire SMBus/I²C interface. Fan speed is controlled according to the system’s required temperature profile and permits lower fan power consumption, longer battery run time and lower acoustical generated noise versus systems that only provide simple on-off control for the fan.The LTC1695 incorporates a 180mA low dropout linear regulator, a 2-wire SMBus/I²C interface and a 6-bit DAC. Fan speed is controlled by varying the fan’s terminal voltage through the output voltage of the LTC1695’s linear regulator. The LTC1695’s output voltage is programmed by sending a 6-bit digital code to the LTC1695 DAC via the SMBus. To eliminate fan start-up problems at lower fan voltages, users can enable the LTC1695’s boost start feature that provides the DAC’s full-scale output voltage for 250ms before decreasing to the programmed output voltage.The LTC1695 includes output current limiting and thermal shutdown as well as status monitors that can be read back by the microprocessor during fault conditions. The LTC1695 is available in a 5-lead SOT-23 package.ApplicationsNotebook ComputersSpot CoolingPortable InstrumentsBattery-Powered SystemsDC Motor ControlWhite LED Power SuppliesProgrammable Low Dropout Regulator

The LTC1696 is a standalone power supply overvoltage monitor and protection device designed to protect a power supply load in the event of an overvoltage fault. It monitors two adjustable output voltages. If an overvoltage condition is detected, the output drives either an external SCR crowbar or turns off external back-to-back N-channel MOSFETs, thereby, disconnecting the input voltage from the power supply.Pin 6 offers three functions. By connecting a capacitor to this pin, the internal glitch filter time delay can be programmed. Without the capacitor, the default time delay is determined by an internal capacitor. This pin also serves as a reset input to clear the internal latch after an overvoltage fault condition. By pulling it high, the OUT pin is activated if the FB1 and FB2 voltages remain below the trip threshold.The LTC1696 is available in the low profile (1mm) ThinSOT package.ApplicationsTelecommunication SystemsComputer SystemsIndustrial Control SystemsNotebook Computers

The LTC1698 is a precision secondary-side forward converter controller that synchronously drives external N-channel MOSFETs. It is designed for use with the LT3781 primary-side synchronous forward converter controller to create a completely isolated power supply. The LT3781 synchronizes the LTC1698 through a small pulse transformer and the LTC1698 drives a feedback optocoupler to close the feedback loop. Output accuracy of ±0.8% and high efficiency over a wide range of load currents are obtained.The LTC1698 provides accurate secondary-side current limit using an external current sense resistor. The input voltage at the MARGIN pin provides ±5% output voltage adjustment. A power good flag and overvoltage input are provided to ensure proper power supply conditions. An auxiliary 3.3V logic supply is included that supplies up to 10mA of output current.Applications48V Input Isolated DC/DC ConvertersIsolated Telecommunication Power SystemsDistributed Power Step-Down ConvertersIndustrial Control SystemsAutomotive and Heavy Equipment

The LTC1699-80, LTC1699-81 and LTC1699-82 are precision (±0.35% max), digitally programmed resistor dividers that comply with Intel 5-bit mobile (LTC1699-80), desktop VRM8.4 (LTC1699-81) and VRM9.0 (LTC1699-82) VID specifications. Each IC can switch the output of a DC/DC converter between two set voltages. A digital input pin, SEL, selects one of two divider settings stored into registers via a 2-wire SMBus interface.The SMBus interface uses Write Word protocol to setup the registers and to turn the DC/DC converters on or off. Read Word protocol is used to verify register contents and to return the On/Off status of the converters. The LTC1699-80, LTC1699-81 and LTC1699-82 incorporate safeguards against errors due to bus conflicts.Three open-drain N-channel outputs (CPU_ON, IO_ON and CLK_ON) are provided to turn DC/DC converter supplies on or off via their RUB/SS inputs. A global control pin, VRON is used to turn the converters on or off simultaneously. An internal timer pulls the PGOOD pin low for 50µs if the divider setting changes or the converters are turned on via the SMBus and the VRON pin.ApplicationsIntel Desktop Pentium®III Power SupplyIntel Mobile Pentium®Power Supply with Intel SpeedStep™TechnologyDesktop AMD Athlon™Power SupplySoftware Programmable Remote Power SupplyPower Supplies with Voltage Margining

The LTC1701/LTC1701B are the industry's first SOT-23 step-down, current mode, DC/DC converters. Intended for low to medium power applications, they operate from 2.5V to 5.5V input voltage range and switch at 1MHz, allowing the use of tiny, low cost capacitors and inductors 2mm or less in height. The output voltage is adjustable from 1.25V to 5V. A built-in 0.28Ω switch allows up to 0.5A of output current at high efficiency. OPTI-LOOP™compensation allows the transient response to be optimized over a wide range of loads and output capacitors.The LTC1701 incorporates automatic power saving BurstMode™operation to reduce gate charge losses when the load current drops below the level required for continuous operation. The LTC1701B operates continuously to very low load currents to provide low ripple at the expense of light load efficiency. With no load, the LTC1701 draws only 135µA. In shutdown, both devices draw less than 1µA, making them ideal for current sensitive applications.Their small size and switching frequency enables a complete DC/DC converter function to consume less than 0.3 square inches of PC board area.ApplicationsPDAs/Palmtop PCsDigital CamerasCellular PhonesPortable Media PlayersPC CardsHandheld Equipment

The LTC1702A is a dual switching regulator controller optimized for high efficiency with low input voltages. It includes two complete, on-chip,independent switching regulator controllers each designed to drive a pair of external N-channel MOSFETs in a voltage mode feedback,synchronous buck configuration. The LTC1702A uses a constant-frequency, true PWM design switching at 550kHz, minimizing external component size and cost and maximizing load transient performance. The synchronous buck architecture automatically shifts to discontinuous and then to Burst Mode®operation as the output load decreases, ensuring maximum efficiency over a wide range of load currents.The LTC1702A features an onboard reference trimmed to 0.5% and can provide better than 1% regulation at the converter outputs. Open-drain logic outputs indicate whether either output has risen to within 5% of the final output voltage and an optional latching FAULT mode protects the load if the output rises 15% above the intended voltage. Each channel can be enabled independently; with both channels disabled, the LTC1702A shuts down and supply current drops below 100µA.ApplicationsMicroprocessor, DSP Core and I/O SuppliesMultiple Logic Supply GeneratorDistributed Power ApplicationsHigh Efficiency Power Conversion