Analog Devices Inc./Maxim Integrated

The LTC1430A is a high power, high efficiency switching regulator controller optimized for 5V to 1.xV-3.xV applications. It includes a precision internal reference and an internal feedback system that can provide output regulation of ±1% over temperature, load current and line voltage shifts. The LTC1430A uses a synchronous switching architecture with two N-channel output devices, eliminating the need for a high power, high cost P-channel device. Additionally, it senses output current across the drain-source resistance of the upper N-channel FET, providing an adjustable current limit without an external low value sense resistor.The LTC1430A includes a fixed frequency PWM oscillator for low output ripple under virtually all operating conditions. The 200kHz free-running clock frequency can be externally adjusted from 100kHz to above 500kHz. The LTC1430A’s maximum duty cycle is typically 93.5% compared to 88% for the LTC1430. This permits 3.3V to 2.xV conversion using a low power 5V supply. The LTC1430A features low 350µA quiescent current, allowing greater than 90% efficiency operation in converter designs from 1A to greater than 50A output current. Shutdown mode drops the LTC1430A supply current to 1µA.For new designs, refer to the LTC3830.ApplicationsPower Supply for Pentium®II and AMD-K6®MicroprocessorsHigh Power 5V to 3.xV RegulatorsLocal Regulation for Dual Voltage Logic BoardsLow Voltage, High Current Battery Regulation

The LTC1433/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. Both devices operate at a fixed frequency with the LTC1434 phase-lockable to an external clock signal.Both devices incorporate two internal P-channel power MOSFETs with a parallel combined resistance of 0.6Ω (at a supply of 10V). The Adaptive Power output stage selectively drives one or both of the switches at frequencies up to 700kHz to reduce switching losses and maintain high efficiencies at low output currents.The LTC1433/LTC1434 are capable of supplying up to 450mA of output current and boasts a ±2.4% output voltage accuracy. An internal low-battery detector has the same level of accuracy as the output voltage. A power-on reset timer (POR) is included which generates a signal delayed by 65536/fCLK(300ms typ) after the output is within 5% of the regulated output voltage.Ideal for current sensitive applications, the devices draw only 470µA of quiescent current. In shutdown the devices draw a mere 15µA. To further maximize the life of the battery source, the internal P-channel MOSFET switch is turned on continuously in dropout.ApplicationsCellular TelephonesPortable InstrumentsWireless ModemsRF CommunicationsDistributed Power SystemsScannersBattery-Powered Equipment

The LTC1433/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. Both devices operate at a fixed frequency with the LTC1434 phase-lockable to an external clock signal.Both devices incorporate two internal P-channel power MOSFETs with a parallel combined resistance of 0.6Ω (at a supply of 10V). The Adaptive Power output stage selectively drives one or both of the switches at frequencies up to 700kHz to reduce switching losses and maintain high efficiencies at low output currents.The LTC1433/LTC1434 are capable of supplying up to 450mA of output current and boasts a ±2.4% output voltage accuracy. An internal low-battery detector has the same level of accuracy as the output voltage. A power-on reset timer (POR) is included which generates a signal delayed by 65536/fCLK(300ms typ) after the output is within 5% of the regulated output voltage.Ideal for current sensitive applications, the devices draw only 470µA of quiescent current. In shutdown the devices draw a mere 15µA. To further maximize the life of the battery source, the internal P-channel MOSFET switch is turned on continuously in dropout.ApplicationsCellular TelephonesPortable InstrumentsWireless ModemsRF CommunicationsDistributed Power SystemsScannersBattery-Powered Equipment

The LTC1436A/LTC1437A are synchronous step-down switching regulator controllers that drive external N-channel power MOSFETs in a phase lockable, fixed frequency architecture. The Adaptive Power™output stage selectively drives two N-channel MOSFETs at frequencies up to 400kHz while reducing switching losses to maintain high efficiencies at low output currents.An auxiliary 0.5A linear regulator using an external PNP pass device provides a low noise, low dropout voltage source. A secondary winding feedback control pin (SFB) guarantees regulation regardless of the load on the main output by forcing continuous operation.An additional comparator is available for use as a lowbattery detector. A power-on reset timer (POR) is included which generates a signal delayed by 65536/fCLK(300ms typically) after the output is within 5% of the regulated output voltage. Internal resistive dividers provide pin selectable output voltages with remote sense capability.The operating current level is user-programmable via an external current sense resistor. Wide input supply range allows operation from 3.5V to 30V (36V maximum).ApplicationsNotebook and Palmtop Computers, PDAsCellular Telephones and Wireless ModemsPortable InstrumentsBattery-Operated DevicesDC Power Distribution Systems

The LTC1438/LTC1439 are dual, synchronous stepdown switching regulator controllers which drive external N-channel power MOSFETs in a phase-lockable fixed frequency architecture. The Adaptive Power™output stage selectively drives two N-channel MOSFETs at frequencies up to 400kHz while reducing switching losses to maintain high efficiencies at low output currents.An auxiliary 0.5A linear regulator using an external PNP pass device provides a low noise, low dropout voltage source. A secondary winding feedback control pin (SFB1) guarantees regulation regardless of load on the main output by forcing continuous operation.An additional comparator is available for use as a low battery detector. A power-on reset timer (POR) is included which generates a signal delayed by 65536/fCLK(typ 300ms) after the output is within 5% of the regulated output voltage. Internal resistive dividers provide pin selectable output voltages with remote sense capability on one of the two outputs.The operating current levels are user-programmable via external current sense resistors. Wide input supply range allows operation from 3.5V to 30V (36V maximum).ApplicationsNotebook and Palmtop Computers, PDAsPortable InstrumentsBattery-Operated DevicesDC Power Distribution Systems

The LTC1440 is an ultralow power comparator with a built-in voltage reference. The comparator features less than 4.0µA supply current over temperature. The internal reference is 1.182V with ±1% accuracy. The LTC1440 has programmable hysteresis and TTL/CMOS outputs that sink and source current. The reference output can drive a bypass capacitor of up to 0.01µF without oscillation.The comparators operate from a single 2V to 11V supply or a dual ±1V to ±5.5V supply. Comparator hysteresis is easily programmed by using two resistors and the HYST pin. Each comparator’s input operates from the negative supply to within 1.3V of the positive supply. The comparator output stage can continuously source up to 40mA. By eliminating the cross-conducting current that normally happens when the comparator changes logic states, the power supply glitches are eliminated.The LTC1440 is available in a 3mm × 3mm × 0.75mm DFN package, as well as 8-pin PDIP and SO-8.ApplicationsBattery-Powered System MonitoringThreshold DetectorsWindow ComparatorsOscillator Circuits