Analog Devices

The LT1271 and LT1269 are monolithic high power switching regulators. Identical to the popular LT1070, except for switching frequency (LT1271 = 60kHz, LT1269 = 100kHz) and slightly lower switch current, they can be operated in all standard switching configurations including buck, boost, flyback and inverting. A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. Integration of all functions allows the LT1271/LT1269 to be built in a standard TO-220 power package. This makes them extremely easy to use and provides "bust proof" operation similar to that obtained with 3-pin linear regulators.The LT1271/LT1269 operate with supply voltages from 3.5V to 30V, and draw only 7mA quiescent current. By utilizing current mode switching techniques, they provides excellent AC and DC load and line regulation.A patented adaptive antisat switch drive allows very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 100µA typical for standby operation.User Note:This data sheet is only intended to provide specifications, graphs, and a general functional description of the LT1271/LT1269. Application circuits are included to show the capability of the LT1271/LT1269. A complete design manual (AN-19) should be obtained to assist in developing new designs. This manual contains a comprehensive discussion of both the LT1070 and the external components used with it, as well as complete formulas for calculating the values of these components. The manual can also be used for the LT1271/LT1269 by factoring in the higher switch current rating and higher operating frequency.ApplicationsBoost ConverterHigh Efficiency Buck ConverterPC Power Supply with Multiple OutputsBattery Up-ConverterNegative-to-Positive Converter

The LT1270A/LT1270 are monolithic high power switching regulators. Identical to the popular LT1070, except for switching frequency (60kHz) and higher switch current, they can be operated in all standard switching configurations including buck, boost, flyback, and inverting. A high current, high efficiency switch is included on the die along with all oscillator, control, and protection circuitry. Integration of all functions allows the LT1270A/LT1270 to be built in a standard TO-220 power package. This makes it extremely easy to use and provides "bust proof" operation similar to that obtained with 3-pin linear regulators.The LT1270A/LT1270 operate with supply voltages from 3.5V to 30V, and draw only 7mA quiescent current. By utilizing current-mode switching techniques, they provide excellent AC and DC load and line regulation.The LT1270A/LT1270 use adaptive anti-sat switch drive to allow very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 100mA typical for standby operation.ApplicationsHigh Efficiency Buck ConverterPC Power Supply with Multiple OutputsBattery UpconverterNegative-to-Positive ConverterUser Note:This data sheet is only intended to provide specifications, graphs and a general functional description of the LT1270A/LT1270. Application circuits are included to show the capability of the LT1270A/LT1270. A complete design manual (AN-19) should be obtained to assist in developing new designs. AN-19 contains a comprehensive discussion of both the LT1070 and the external components used with it, as well as complete formulas for calculating the values of these components. AN-19 can also be used for the LT1270A/LT1270 by factoring in the higher switch current rating and higher operating frequency.A comprehensive CAD program called SwitcherCad is also available. Contact the local sales office in your area or the factory direct.

The LT1271 and LT1269 are monolithic high power switching regulators. Identical to the popular LT1070, except for switching frequency (LT1271 = 60kHz, LT1269 = 100kHz) and slightly lower switch current, they can be operated in all standard switching configurations including buck, boost, flyback and inverting. A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. Integration of all functions allows the LT1271/LT1269 to be built in a standard TO-220 power package. This makes them extremely easy to use and provides "bust proof" operation similar to that obtained with 3-pin linear regulators.The LT1271/LT1269 operate with supply voltages from 3.5V to 30V, and draw only 7mA quiescent current. By utilizing current mode switching techniques, they provides excellent AC and DC load and line regulation.A patented adaptive antisat switch drive allows very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 100µA typical for standby operation.User Note:This data sheet is only intended to provide specifications, graphs, and a general functional description of the LT1271/LT1269. Application circuits are included to show the capability of the LT1271/LT1269. A complete design manual (AN-19) should be obtained to assist in developing new designs. This manual contains a comprehensive discussion of both the LT1070 and the external components used with it, as well as complete formulas for calculating the values of these components. The manual can also be used for the LT1271/LT1269 by factoring in the higher switch current rating and higher operating frequency.ApplicationsBoost ConverterHigh Efficiency Buck ConverterPC Power Supply with Multiple OutputsBattery Up-ConverterNegative-to-Positive Converter

The LT1280A/LT1281A are dual RS232 driver/receiver pairs with integral charge pump to generate RS232 voltage levels from a single 5V supply. These circuits feature rugged bipolar design to provide operating fault tolerance and ESD protection unmatched by competing CMOS designs. Using only 0.1µF external capacitors, these circuits consume only 40mW of power, and can operate to 120kbaud even while driving heavy capacitive loads. New ESD structures on the chip allow the LT1280A/LT1281A to survive multiple ±10kV strikes, eliminating the need for costly TransZorbs®on the RS232 line pins. The LT1280A/LT1281A are fully compliant with EIA RS232 standards. Driver outputs are protected from overload, and can be shorted to ground or up to ±30V without damage. During shutdown or power-off conditions, driver and receiver outputs are in a high impedance state, allowing line sharing.The LT1281A is available in 16-pin DIP and SO packages. The LT1280A is supplied in 18-pin DIP and SO packages for applications which require shutdown.ApplicationsPortable ComputersBattery-Powered SystemsPower Supply GeneratorTerminalsModems

The LT1280A/LT1281A are dual RS232 driver/receiver pairs with integral charge pump to generate RS232 voltage levels from a single 5V supply. These circuits feature rugged bipolar design to provide operating fault tolerance and ESD protection unmatched by competing CMOS designs. Using only 0.1µF external capacitors, these circuits consume only 40mW of power, and can operate to 120kbaud even while driving heavy capacitive loads. New ESD structures on the chip allow the LT1280A/LT1281A to survive multiple ±10kV strikes, eliminating the need for costly TransZorbs®on the RS232 line pins. The LT1280A/LT1281A are fully compliant with EIA RS232 standards. Driver outputs are protected from overload, and can be shorted to ground or up to ±30V without damage. During shutdown or power-off conditions, driver and receiver outputs are in a high impedance state, allowing line sharing.The LT1281A is available in 16-pin DIP and SO packages. The LT1280A is supplied in 18-pin DIP and SO packages for applications which require shutdown.ApplicationsPortable ComputersBattery-Powered SystemsPower Supply GeneratorTerminalsModems

The LT1302/LT1302-5 are micropower step-up DC/DC converters that maintain high efficiency over a wide range of output current. They operate from a supply voltage as low as 2V and feature automatic shifting between Burst Mode operation at light load, and current mode operation at heavy load.The internal low loss NPN power switch can handle current in excess of 2A and switch at frequencies up to 400kHz. Quiescent current is just 200µA and can be further reduced to 15µA in shutdown.Available in 8-pin PDIPor 8-pin SO packaging, the LT1302/LT1302-5 have the highest switch current rating of any similarly packaged switching regulators presently on the market.ApplicationsNotebook and Palmtop ComputersPortable InstrumentsPersonal Digital AssistantsCellular TelephonesFlash Memory

The LT1303/LT1303-5 are micropower step-up high efficiency DC/DC converters using Burst Mode™operation. They are ideal for use in small, low-voltage battery-operated systems. The LT1303-5 accepts an input voltage between 1.8V and 5V and convertsit to a regulated 5V. The LT1303 is an adjustable version that can supply an output voltage up to 25V. Quiescent current is only 120µA from the battery and the shutdown pin further reduces current to 10µA. The low-battery detector provides an open-collector output that goes low when the input voltage drops below a preset level. The on-chip NPN power switch has a low 170mV saturation voltage at a switch current of 1A. The LT1303/1303-5 are available in 8-lead PDIP or SO packages, easing board space requirements.For higher output current, please see the LT1305 or LT1302.ApplicationsEL Panel Drivers2-Cell and 3-Cell to 5V ConversionPalmtop ComputersPortable InstrumentsBar-Code ScannersWireless Systems

The LT1304 is a micropower step-up DC/DC converter ideal for use in small, low voltage, battery-operated systems. The devices operate from a wide input supply range of 1.5V to 8V. The LT1304-3.3 and LT1304-5 generate regulated outputs of 3.3V and 5V and the adjustable LT1304 can deliver output voltages up to 25V. Quiescent current, 120µA in active mode, decreases to just 10µA in shutdown with the low-battery detector still active. Peak switch current, internally set at 1A, can be reduced by adding a single resistor from the ILIMpin to ground. The high speed operation of the LT1304 allows the use of small, surface-mountable inductors and capacitors. The LT1304 is available in an 8-lead SO package.Applications2-, 3-, or 4-Cell to 5V or 3.3V Step-UpPortable InstrumentsBar Code ScannersPalmtop ComputersDiagnostic Medical InstrumentationPersonal Data Communicators/Computers

The LT1305 is a micropower step-up DC/DC converter that uses Burst Mode™operation. Similar to the LT1303, the LT1305 features a 2A internal low-loss switch and can deliver up to four times the output power of the LT1303.Quiescent current is only 120µA and the Shutdown pin further reduces current to 10µA. A low-battery detector provides an open-collector output that goes low when the input voltage drops below a preset level. The LT1305 is available in an 8-pin SO, easing board space requirements.Applications2-Cell and 3-Cell to 5V ConversionEL Panel DriversPortable Instruments

The LT1306 is a fully integrated, fixed frequency synchronous boost converter capable of generating 5V at 1A from a Li-Ion cell. The device contains both the main power switch and synchronous rectifier on chip and automatically disconnects the output from the input in shutdown, eliminating the need for external load disconnect circuitry. Additionally, the output remains regulated when VINexceeds VOUT, allowing difficult step-up/step-down converter functions to be easily realized using a single inductor.The internal 300kHz oscillator of the LT1306 can be easily synchronized to an external clock from 425kHz to 500kHz. This allows switching harmonics to be tightly controlled and eliminates any beat frequencies that may result from a multifrequency system. The LT1306 automatically shifts into power saving Burst Mode™operation at light loads. At heavy loads the LT1306 operates in fixed frequency current mode. No-load quiescent current is 160µA and reduces to 9µA in shutdown mode.The LT1306 is available in an SO-8 package.ApplicationsSatellite PhonesPortable InstrumentsPersonal Digital AssistantsPalmtop Computers