Analog Devices

The LT1571 PWM battery charger is a simple, efficient solution to fast-charge rechargeable batteries including lithium-ion (Li-Ion), nickel-metal-hydride (NiMH) and nickel-cadmium (NiCd) using constant-current and/or constant-voltage control. The internal switch is capable of delivering 1.5A DC current (2A peak current). The onboard current sense resistor (0.1Ω) allows simple charge current programming to within 5% accuracy using a low cost external resistor. The constant-voltage output can be selected for 4.1V or 4.2V per cell with 0.6% accuracy.LT1571 can charge batteries ranging from 1V to 20V. A saturating switch operating at 200kHz (LT1571-1, LT1571-2) or 500kHz (LT1571-5) gives high efficiency and small charger size. A logic output (flag) indicates Li-Ion near full charge when the charge current drops to 20% of the programmed value. The LT1571-1 and LT1571-2 are in a 28-pin fused lead narrow SSOP power package. The LT1571-5 is in a 16-pin fused lead narrow SSOP power package.ApplicationsCellular Phones, PDAs, Notebook Computers, Portable InstrumentsCradle Chargers for Li-Ion, NiCd, NiMH and Lead-Acid Rechargeable Batteries

The LT1573 is a regulator driver IC designed to provide a low cost solution for applications requiring high current, low dropout and fast transient response. When combined with an external PNP power transistor, this device provides load current up to 5A with dropout voltages as low as 0.35V. The LT1573 circuitry 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 as an adjustable regulator with an output range of 1.27V to 6.8V and with fixed output voltages of 2.5V, 2.8V and 3.3V. Output accuracy is better than 1% to meet the critical regulation requirement of fast microprocessors. A special 8-pin, fused-lead surface mount package is used to minimize regulator footprint and provide adequate heat sinking.Applications3.3V to 2.5V RegulatorMicroprocessor Power SourcePost Regulator for Switching SuppliesHigh Efficiency Linear RegulatorsUltralow Dropout RegulatorsLow Voltage Linear Regulators

The LT1575/LT1577 are single/dual controller ICs that drive low cost external N-channel MOSFETs as source followers to produce ultrafast transient response, low dropout voltage regulators.The LT1575/LT1577 achieve unprecedented transient-load performance by eliminating expensive tantalum or bulk electrolytic output capacitors in the most demanding modern microprocessor applications. Precision-trimmed adjustable and fixed output voltage versions accommodate any required microprocessor power supply voltage. Selection of the N-channel MOSFET RDS(ON)allows very low dropout voltages to be achieved.Unique protection features include a high side current limit amplifier that activates a fault protection timer circuit. A multifunction Shutdown pin provides either current limit time-out with latch off, overvoltage protection, thermal shutdown or a combination of these functions. The LT1575 is available in 8-pin SO or PDIP and the LT1577 is available in 16-pin narrow body SO.ApplicationsPentium®Processor SuppliesPowerPC™Supplies5V to 3.XXV or 3.3V to 2.XXV Microprocessor SuppliesGTL TerminationLow Voltage Logic Supplies

The LT1576 is a 200kHz monolithic buck mode switching regulator. A 1.5A switch is included on the die along with all the necessary oscillator, control and logic circuitry. The topology is current mode for fast transient response and good loop stability. The LT1576 is a modified version of the industry standard LT1376 optimized for noise sensitive applications.In addition, the reference voltage has been lowered to allow the device to produce output voltages down to 1.2V. Quiescent current has been reduced by a factor of two. Switch on resistance has been reduced by 30%. Switch transition times have been slowed to reduce EMI generation. The oscillator frequency has been reduced to 200kHz to maintain high efficiency over a wide output current range.The pinout has been changed to improve PC layout by allowing the high current high frequency switching circuitry to be easily isolated from low current noise sensitive control circuitry. The new SO-8 package includes a fused ground lead which significantly reduces the thermal resistance of the device to extend the ambient operating temperature range. There is an optional function of shutdown or synchronization. Standard surface mount external parts can be used including the inductor and capacitors.ApplicationsPortable ComputersBattery-Powered SystemsBattery ChargerDistributed Power

The LT1575/LT1577 are single/dual controller ICs that drive low cost external N-channel MOSFETs as source followers to produce ultrafast transient response, low dropout voltage regulators.The LT1575/LT1577 achieve unprecedented transient-load performance by eliminating expensive tantalum or bulk electrolytic output capacitors in the most demanding modern microprocessor applications. Precision-trimmed adjustable and fixed output voltage versions accommodate any required microprocessor power supply voltage. Selection of the N-channel MOSFET RDS(ON)allows very low dropout voltages to be achieved.Unique protection features include a high side current limit amplifier that activates a fault protection timer circuit. A multifunction Shutdown pin provides either current limit time-out with latch off, over-voltage protection, thermal shutdown or a combination of these functions. The LT1575 is available in 8-pin SO or PDIP and the LT1577 is available in 16-pin narrow body SO.ApplicationsPentium®Processor SuppliesPowerPC™Supplies5V to 3.XXV or 3.3V to 2.XXV Microprocessor SuppliesGTL TerminationLow Voltage Logic Supplies

The LT1578 is a 200kHz monolithic buck mode switching regulator. A 1.5A switch is included on the die along with all the necessary oscillator, control and logic circuitry. The topology is current mode for fast transient response and good loop stability. The LT1578 is a modified version of the LT1507 that has been optimized for noise sensitive applications. It will operate over a 4V to 15V input range.In addition, the reference voltage has been lowered to allow the device to produce output voltages down to 1.2V. Quiescent current has been reduced by a factor of two. Switch on resistance has been reduced by 30%. Switch transition times have been slowed to reduce EMI generation. The oscillator frequency has been reduced to 200kHz to maintain high efficiency over a wide output current range.The pinout has been changed to improve PC layout by allowing the high current, high frequency switching circuitry to be easily isolated from low current, noise sensitive control circuitry. The new SO-8 package includes a fused ground lead that significantly reduces the thermal resistance of the device to extend the ambient operating temperature range. Standard surface mount external parts can be used including the inductor and capacitors.ApplicationsPortable ComputersBattery-Powered SystemsBattery ChargerDistributed Power Systems

The LT1579 is a dual input, single output, low dropout regulator. This device is designed to provide an uninterruptible output voltage from two independent input voltage sources on a priority basis. All of the circuitry needed to switch smoothly and automatically between inputs is incorporated.The LT1579 can supply 300mA of output current from either input at a dropout voltage of 0.4V. Quiescent current is 50µA, dropping to 7µA in shutdown. Two comparators are included to monitor input voltage status. Two additional status flags indicate which input is supplying power and provide an early warning against loss of output regulation when both inputs are low. A secondary select pin is provided so that the user can force the device to switch from the primary input to the secondary input. Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting and reverse-current protection.The device is available in fixed output voltages of 3V, 3.3V and 5V, and as an adjustable device with a 1.5V reference voltage. The LT1579 regulators are available in narrow 16-lead SO and 16-lead SSOP packages with all features, and in SO-8 with limited features.ApplicationsDual Battery SystemsBattery Backup SystemsAutomatic Power Management for Battery-Operated Systems

The LT1580 is a 7A low dropout regulator designed to power the new generation of microprocessors. The dropout voltage of this device is 100mV at light loads rising to just 540mV at 7A. To achieve this dropout, a second low current input voltage 1V greater than the output voltage, is required. The device can also be used as a single supply device where dropout is comparable to an LT1584.Several other new features have been added to the LT1580. A remote SENSE pin is brought out. This feature virtually eliminates output voltage variations due to load changes. Typical load regulation, measured at the SENSE pin, for a load current step of 100mA to 7A is less than 1mV.The LT1580 has fast transient response, equal to the LT1584. On fixed voltage devices, the ADJ pin is brought out. A small capacitor on the ADJ pin further improves transient response.This device is ideal for generating processor supplies of 2V to 3V on motherboards where both 5V and 3.3V supplies are available.ApplicationsMicroprocessor SuppliesPost Regulators for Switching SuppliesHigh Current Regulators5V to 3.XXV for Pentium®Processors Operating at 90MHz to 166MHz and Beyond3.3V to 2.9V for Portable Pentium ProcessorPower PC™Series Power Supplies

The LT1581 is a 10A low dropout regulator designed to power the new generation of microprocessors. The dropout voltage of this device is 100mV at light loads rising to just 430mV at 10A. To achieve this dropout a second low current input voltage 1V greater than the output voltage is required. The device can also be used as a single supply device where dropout is comparable to an LT1584.Several other new features have been added to the LT1581. A remote SENSE pin is brought out. This feature virtually eliminates output voltage variations due to load changes. Typical load regulation for a load current step of 100mA to 10A, measured at the SENSE pin, is less than 1mV.The LT1581 has fast transient response, equal to the LT1584. On fixed voltage devices, the ADJUST pin is brought out. A small capacitor on the ADJUST pin further improves transient response.This device is ideal for generating processor supplies of 2V to 3V on motherboards where both 5V and 3.3V supplies are available.ApplicationsMicroprocessor SuppliesPost Regulators for Switching SuppliesHigh Current Regulators5V to 3.XXV for Pentium®Processors Operating at 90MHz to 166MHz and Beyond3.3V to 2.9V for Portable Pentium ProcessorPowerPC™Series Power Supplies

The LT1584/LT1585/LT1587 are low dropout three terminal regulators with 7A, 4.6A and 3A output current capability, respectively. Design has been optimized for low voltage applications where transient response and minimum input voltage are critical. Similar to the LT1083/4/5 family, it has lower dropout voltage and faster transient response. These improvements make it ideal for low voltage microprocessor applications requiring a regulated 2.5V to 3.6V output with an input supply below 7V.Current limit is trimmed to ensure specified output current and controlled short-circuit current. On-chip thermal limiting provides protection against any combination of overload that would create excessive junction temperatures.The LT1585/LT1587 are available in both the through-hole and surface mount versions of the industry standard 3-pin TO-220 power package. The LT1584 is available in the through-hole 3-pin TO-220 power package.Output CurrentOutput Voltage OptionsLT1584, -3.3, -3.38, -3.45, -3.67AAdj, 3.3V, 3.38V, 3.45V, 3.6VLT1585, -3.3, -3.38, -3.45, -3.64.6AAdj, 3.3V, 3.38V, 3.45V, 3.6VLT1585A, LT1585A-3.35AAdj, 3.3VLT1585-1.5, LT1585A-1.54.6A / 5AFixed 1.5VLT1587, -3.3, -3.45, -3.63AAdj, 3.3V, 3.45V, 3.6VLT1587-1.53AFixed 1.5VApplicationsPentium™Processor SuppliesPowerPC™SuppliesOther 2.5V to 3.6V Microprocessor SuppliesLow Voltage Logic SuppliesBattery-Powered CircuitryPost Regulator for Switching Supply