Analog Devices

The LT1511 current mode PWM battery charger is the simplest, most efficient solution to fast charge modern rechargeable batteries including lithium-ion (Li-Ion), nickel-metal-hydride (NiMH) and nickel-cadmium (NiCd) that require constant-current and/or constant-voltage charging. The internal switch is capable of delivering 3A* DC current (4A peak current). Full-charging current can be programmed by resistors or a DAC to within 5%. With 0.5% reference voltage accuracy, the LT1511 meets the critical constant-voltage charging requirement for Li-Ion cells.A third control loop is provided to regulate the current drawn from the AC adapter. This allows simultaneous operation of the equipment and battery charging without overloading the adapter. Charging current is reduced to keep the adapter current within specified levels.The LT1511 can charge batteries ranging from 1V to 20V. Ground sensing of current is not required and the battery’s negative terminal can be tied directly to ground. A saturating switch running at 200kHz gives high charging efficiency and small inductor size. A blocking diode is not required between the chip and the battery because the chip goes into sleep mode and drains only 3µA when the wall adapter is unplugged.* See LT1510 for 1.5A ChargerApplicationsChargers for NiCd, NiMH, Lead-Acid, LithiumRechargeable BatteriesSwitching Regulators with Precision Current Limit

The LT1512 is a 500kHz current mode switching regulator specially configured to create a constant-current/constant-voltage battery charger. In addition to the usual voltage feedback node, it has a current sense feedback circuit for accurately controlling output current of a flyback or SEPIC (Single-Ended Primary Inductance Converter) topology charger. These topologies allow the current sense circuit to be ground referred and completely separated from the battery itself, simplifying battery switching and system grounding problems. In addition, these topologies allow charging even when the input voltage is lower than the battery voltage.Maximum switch current on the LT1512 is 1.5A. This allows battery charging currents up to 1A for a single lithium-ion cell. Accuracy of 1% in constant-voltage mode is perfect for lithium battery applications. Charging current can be easily programmed for all battery types.ApplicationsBattery Charging of NiCd, NiMH, Lead-Acid or Lithium Rechargeable CellsPrecision Current Limited Power SupplyConstant-Voltage/Constant-Current SupplyTransducer Excitation*Maximum Input Voltage = 40V – VBAT

The LT1513 is a 500kHz current mode switching regulator specially configured to create a constant- or programmable-current/constant-voltage battery charger. In addition to the usual voltage feedback node, it has a current sense feedback circuit for accurately controlling output current of a flyback or SEPIC (Single-Ended Primary Inductance Converter) topology charger. These topologies allow the current sense circuit to be ground referred and completely separated from the battery itself, simplifying battery switching and system grounding problems. In addition, these topologies allow charging even when the input voltage is lower than the battery voltage. The LT1513 can also drive a CCFL Royer converter with high efficiency in floating or grounded mode.Maximum switch current on the LT1513 is 3A. This allows battery charging currents up to 2A for a single lithium-ion cell. Accuracy of 1% in constant-voltage mode is perfect for lithium battery applications. Charging current can be easily programmed for all battery types.ApplicationsCharging of NiCd, NiMH, Lead-Acid or Lithium Rechargeable CellsPrecision Current Limited Power SupplyConstant-Voltage/Constant-Current SupplyTransducer ExcitationUniversal Input CCFL Driver

The LT1521/LT1521-3/LT1521-3.3/LT1521-5 are low dropout regulators with micropower quiescent current and shutdown. These devices are capable of supplying 300mA of output current with a dropout voltage of 0.5V.Designed for use in battery-powered systems, the low quiescent current, 12μA operating and 6μA in shutdown, makes them an ideal choice. The quiescent current is well controlled; it does not rise in dropout as it does with many other low dropout PNP regulators.Other features of the LT1521/LT1521-3/LT1521-3.3/LT1521-5 include the ability to operate with very small output capacitors. They are stable with only 1.5μF on the output while most older devices require between 10μF and 100μF for stability. Small ceramic capacitors can be used, enhancing manufacturability. Also, the input may be connected to voltages lower than the output voltage, including negative voltages, without reverse current flow from output to input. This makes the LT1521 series ideal for backup power situations where the output is held high and the input is low or reversed. Under these conditions only 5μA will flow from the output pin to ground.APPLICATIONSLow Current RegulatorRegulator for Battery-Powered SystemsPost Regulator for Switching Supplies

The LT1529/LT1529-3.3/LT1529-5 are 3A low dropout regulators with micropower quiescent current and shutdown. The devices are capable of supplying 3A of output current with a dropout voltage of 0.6V. Designed for use in battery-powered systems, the low quiescent current, 50µA operating and 16µA in shutdown, make them an ideal choice. The quiescent current is well controlled; it does not rise in dropout as it does with many other low dropout PNP regulators.Other features of the LT1529 /LT1529-3.3/LT1529-5 include the ability to operate with small output capacitors. They are stable with 22µF on the output while most older devices require up to 100µF for stability. Small ceramic capacitors can be used, enhancing manufacturabiltiy. Also the input may be connected to voltages lower than the output voltage, including negative voltages, without reverse current flow from output to input. This makes the LT1529/LT1529-3.3/LT1529-5 ideal for backup power situations where the output is held high and the input is at ground or reversed. Under these conditions, only 16µA will flow from the OUTPUT pin to ground. The devices are available in 5-lead TO-220 and 5-lead DD packages.ApplicationsHigh Efficiency RegulatorRegulator for Battery-Powered SystemsPost Regulator for Switching Supplies5V to 3.3V Logic Regulator

The LT1533 is a new class of switching regulator designed to reduce conducted and radiated electromagnetic interference (EMI). Ultralow noise and EMI are achieved by providing user control of the output switch slew rates. Voltage and current slew rates can be independently programmed to optimize switcher harmonic content versus efficiency. The LT1533 can reduce high frequency harmonic power by as much as 40dB with only minor losses in efficiency.The LT1533 utilizes a dual output switch current mode architecture optimized for low noise topologies. The IC includes two 1A power switches along with all necessary oscillator, control and protection circuitry. Unique error amp circuitry can regulate both positive and negative voltages. The internal oscillator may be synchronized to an external clock for more accurate placement of switching harmonics. Protection features include cycle by cycle current limit protection, undervoltage lockout and thermal shutdown.Low minimum supply voltage and low supply current during shutdown make the LT1533 well suited for portable applications. The part may also be forced into a 50% duty cycle mode for unregulated applications. The LT1533 is available in the 16-pin narrow SO package.ApplicationsPrecision Instrumentation SystemsIsolated Supplies for Industrial AutomationMedical InstrumentsWireless CommunicationsSingle Board Data Acquisition Systems

The LT1534/LT1534-1 are a new class of switching regulator designed to reduce conducted and radiated electromagnetic interference (EMI). Ultralow noise and EMI are achieved by providing user control of the output switch slew rates. Voltage and current slew rates can be independently programmed to optimize switcher harmonic content versus efficiency.The LT1534/LT1534-1 can reduce high frequency harmonic power by as much as 40dB with only minor losses in efficiency. The LT1534/LT1534-1 utilize a current mode architecture optimized for low noise boost topologies. The ICs include a 2A power switch along with all necessary oscillator, control and protection circuitry. Unique error amp circuitry can regulate both positive and negative voltages. The internal oscillator may be synchronized to an external clock for more accurate placement of switching harmonics. Protection features include cycle-by-cycle current limit protection, undervoltage lockout and thermal shutdown.Low minimum supply voltage and low supply current during shutdown make the LT1534/LT1534-1 well suited for portable applications. The LT1534/LT1534-1 are available in the 16-pin narrow SO package.ApplicationsPrecision Instrumentation SystemsIsolated Supplies for Industrial AutomationMedical InstrumentsWireless CommunicationsSingle Board Data Acquisition Systems

The LT1537 is a three-driver, five-receiver RS232 transceiver, pin compatible with the LT1137A, offering performance improvements and two shutdown modes. The LT1537µs charge pump is designed for extended compliance and can deliver over 35mA of load current. Supply current is typically 8mA, competitive with similar CMOS devices. An advanced driver output stage operates up to 250kbaud while driving heavy capacitive loads.The LT1537 is fully compliant with all RS232 specifications. Special bipolar construction techniques protect the drivers and receivers beyond the fault conditions stipulated for RS232. Driver outputs and receiver inputs can be shorted to ±25V without damaging the device or the power supply generator. In addition, the RS232 I/O pins are resilient to multiple ±5kV ESD strikes.The transceiver has two shutdown modes. One mode disables the drivers and the charge pump, the other shuts down all circuitry. While shut down, the drivers and receivers assume high impedance output states.ApplicationsNotebook ComputersPalmtop Computers

The LT1567 is an analog building block optimized for very low noise high frequency filter applications. It contains two wideband rail-to-rail operational amplifiers, one of them internally configured as a unity-gain inverter. With the addition of a few passive components, the LT1567 becomes a flexible second order filter section with cutoff frequency (fC) up to 5MHz, ideal for antialiasing or for channel filtering in high speed data communications systems. A spreadsheet-based design tool is available for designing lowpass and bandpass filters using the LT1567.In addition to low noise and high speed, the LT1567 features single-ended to differential conversion for direct driving of high speed differential input A/D converters. The LT1567 operates from a total power supply voltage of 2.7V to 12V and supports signal-to-noise ratios above 100dB.The LT1567 is available in an 8-lead MSOP package.ApplicationsLow Noise, High Speed Filters to 5MHzLow Noise Differential CircuitsCommunication Channel or Roofing FiltersAntialias or Reconstruction FilteringVideo Signal ProcessingSingle-Ended to Differential Conversion

The LT1568 is an easy-to-use, active-RC filter building block with rail-to-rail inputs and outputs. The internal capacitors of the IC and the GBW product of the internal low noise op amps are trimmed such that consistent and repeatable filter responses can be achieved. With a single resistor value, the LT1568 provides a pair of matched 2-pole Butterworth lowpass filters with unity gain suitable for I/Q channels.By using unequal-valued external resistors, the two 2-pole sections can create different frequency responses or gains. In addition, the two stages may be cascaded to create a single 4-pole filter with a programmable response. Capable of cutoff frequencies up to 10MHz, the LT1568 is ideal for antialiasing or channel filtering in high speed data communications systems. The LT1568 can also be used as a bandpass filter.The LT1568 features very low noise, supporting signal-to-noise ratios of over 90dB. It also provides single-ended to differential signal conversion for directly driving high speed A/D converters. The LT1568 has a shutdown mode that reduces supply current to approximately 0.5mA on a 5V supply.The LT1568 is available in a narrow 16-lead SSOP package.ApplicationsReplaces Discrete RC Active Filters and LC Filter ModulesAntialiasing/Reconstruction FiltersDual or I-and-Q Channels (Two Matched 2nd Order Filters in One Package)Single-Ended to Differential ConversionVideo Signal Processing