Analog Devices

The LTC1727 is a triple supply monitor intended for systems with multiple supply voltages. Each supply monitor has its own open-drain output for individual supply monitoring. A common open-drain reset output remains low until all three supplies have been in compliance for 200ms. Tight 1.5% accuracy specifications and glitch immunity ensure reliable reset operation without false triggering.The LTC1728 is functionally identical to the LTC1727 without the individual monitor outputs.TheRSToutput is guaranteed to be in the correct state for VCC5/VCC25/VCC18or VCC3down to 1V. The LTC1727/LTC1728 may also be configured to monitor any one or two VCCinputs instead of three, depending on system requirements.Very low (10µA typical) supply current makes the LTC1727/LTC1728 ideal for power conscious systems.The LTC1727 is available in an 8-lead MSOP or SO package and the LTC1728 is available in a 5-lead SOT-23 package.ApplicationsDesktop ComputersNotebook ComputersIntelligent InstrumentsPortable Battery-Powered EquipmentNetwork Servers

The LTC1730 is a complete pulse charger for 1-cell lithium-ion batteries. When charging a depleted cell, the internal MOSFET is fully on allowing the current limited input power source to provide charge current to the battery, virtually eliminating heat generation in the charger.As the battery accepts charge and approaches the programmed voltage, the internal MOSFET begins switching off and on with the duty cycle gradually decreasing as the battery approaches a fully charged condition. A programmable timer ends the charge cycle. The end-of-charge condition is indicated at theCHRGpin when the average charge current falls to C/10. Removing the input voltage puts the LTC1730 into a sleep mode, dropping the battery current drain to less than 1µA (maximum).An external sense resistor limits the maximum charge current as a safety precaution against a user connecting a wall adapter with the incorrect or no current limit. The internal MOSFET prevents reverse battery current from flowing if the input voltage is shorted to ground, eliminating the need for a blocking diode.The LTC1730-4 is available in the 16-pin SSOP package and the LTC1730-4.2 is available in the 8-pin SO package.ApplicationsStandalone Lithium-Ion Battery ChargerHandheld ComputersCellular Telephones

The LTC1731 is a complete constant-current/constant-voltage linear charger controller for single cell lithium-ion batteries. Nickel-cadmium (NiCd) and nickel-metal-hydride (NiMH) batteries can also be charged with constant current using external termination. The external sense resistor sets the charge current with 5% accuracy. An internal resistor divider and precision reference set the final float potential with ±1% accuracy. The output float voltage is set internally to 4.1V (LTC1731-4.1) or 4.2V (LTC1731-4.2).When the input supply is removed,the LTC1731 automatically enters a low current sleep mode, dropping the battery drain current to typically 7µA. An internal comparator detects the end-of-charge (C/10) condition while a programmable timer, using an external capacitor, sets the total charge time. Fully discharged cells are automatically trickle charged at 10% of the programmed current until cell voltage exceeds 2.457V.The LTC1731 is available in the 8-pin MSOP and SO packages.Float VoltageLTC1731-4.14.1VLTC1731-4.24.2VLTC1731-8.28.2VLTC1731-8.48.4VApplicationsCellular PhonesHandheld ComputersCharging Docks and CradlesProgrammable Current Source

The LTC1731-8.2/LTC1731-8.4 are complete constant-current/constant-voltage linear charger controllers for 2-cell lithium-ion (Li-Ion)batteries. Nickel-cadmium (NiCd) and nickel-metal-hydride (NiMH) batteries can also be charged with constant current using external termination. The external sense resistor sets the charge current with 7% accuracy. An internal resistor divider and precision reference set the final float potential with 1% accuracy. The output float voltages are set internally to 8.2V (LTC1731-8.2) or 8.4V (LTC1731-8.4).When the input supply is removed, the LTC1731-8.2/LTC1731-8.4 automatically enter a low current sleep mode, dropping the battery drain current to typically 15µA. An internal comparator detects the end-of-charge (C/10) condition while a programmable timer, using an external capacitor, sets the total charge time. Fully discharged cells are automatically trickle charged at 10% of the programmed current until battery voltage exceeds 4.95V.The LTC1731-8.2/LTC1731-8.4 are available in the 8-pin MSOP and SO packages. For 1-cell Li-Ion battery charging, see the LTC1731-4.1 and LTC1731-4.2 data sheets.Float VoltageLTC1731-4.14.1VLTC1731-4.24.2VLTC1731-8.28.2VLTC1731-8.48.4VApplicationsCellular PhonesHandheld ComputersCharging Docks and CradlesProgrammable Current Source

The LTC1732 is a complete constant-current/constant-voltage linear charge controller for lithium-ion (Li-Ion) batteries. Nickel-cadmium (NiCd) and nickel metal-hydride (NiMH) batteries can also be charged with constant current using external termination. Charge current can be programmed with 7% (max) accuracy using external sense and program resistors. An internal resistor divider and precision reference set the final float voltage with 1% accuracy. The SEL pin allows users to charge either 4.1V or 4.2V cells.When the input supply is removed, the LTC1732 automatically enters a low current sleep mode, dropping the battery drain current to 7µA. An internal comparator detects the end-of-charge (C/10) condition while a programmable timer, using an external capacitor, sets the total charge time. Fully discharged cells are automatically trickle charged at 10% of the programmed current until cell voltage exceeds 2.457V.The LTC1732 begins a new charge cycle when a discharged battery is connected to the charger or when the input power is applied. In addition, if the battery remains connected to the charger and the cell voltage drops below 3.8V for the LTC1732-4 or below 4.05V for the LTC1732-4.2, a new charge cycle will begin.The LTC1732 is available in the 10-pin MSOP package.Float VoltageRecharge VoltageLTC1732-44.1V or 4.2V (pin select)3.8VLTC1732-4.24.2V4.05VLTC1732-8.48.4V8.05VApplicationsCellular PhonesHandheld ComputersCharging Docks and Cradles

The LTC1733 is a standalone constant-current/constant-voltage linear charger for lithium-ion batteries with an on-chip power MOSFET. Internal thermal feedback regulates the charge current to limit die temperature during high power operation or high ambient temperature conditions. This feature allows the user to program a high charge current without risk of damaging the LTC1733 or the handheld product.No external current sense resistor is needed and no blocking diode is required due to the internal MOSFET architecture. The charge current and charge time can be set externally with a single resistor and capacitor, respectively. When the input supply (wall adapter) is removed, the LTC1733 automatically enters a low current sleep mode, dropping the battery drain current to less than 5µA.The LTC1733 also includes NTC temperature sensing, C/10 detection circuitry, AC present logic, 4.1V/4.2V pin selectability and low battery charge conditioning (trickle charging).The LTC1733 is available in a 10-pin thermally enhanced MSOP package.ApplicationsCellular TelephonesHandheld ComputersDigital Still CamerasCharging Docks and Cradles

The LTC1734 is a low cost, single cell, constant-current/constant-voltage Li-Ion battery charger controller. When combined with a few external components, the SOT-23 package forms a very small, low cost charger for single cell lithium-ion batteries.The LTC1734 is available in 4.1V and 4.2V versions with 1% accuracy. Constant current is programmed using a single external resistor between the PROG pin and ground. Manual shutdown is accomplished by floating the program resistor while removing input power automatically puts the LT1734 into sleep mode. Both the shutdown and sleep modes drain near zero current from battery.Charge current can be monitored via the voltage on the PROG pin allowing a microcontroller or ADC to read the current and determine when to terminate the charge cycle. The output driver is both current limited and thermally protected to prevent the LTC1734 from operating outside of safe limits. No external blocking diode is required.The LTC1734 can also function as a general purpose current source or as a current source for charging nickel-cadmium (NiCd) and nickel-metal-hydride (NiMH) batteries using external termination.Charge CurrentVfloatLTC1734180mA to 700mA4.1V or 4.2VLTC1734L50mA to 180mA4.2VApplicationsCellular TelephonesHandheld ComputersDigital CamerasCharging Docks and CradlesLow Cost and Small Size ChargersProgrammable Current Source

The LTC1735 is a synchronous step-down switching regulator controller that drives external N-channel power MOSFETs using a fixed frequency architecture. Burst Mode operation provides high efficiency at low load currents. The precision 0.8V reference is compatible with future generation microprocessors. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values.The operating frequency (synchronizable up to 500kHz) is set by an external capacitor allowing maximum flexibility in optimizing efficiency. A forced continuous control pin reduces noise and RF interference and can assist secondary winding regulation by disabling Burst Mode operation when the main output is lightly loaded.Protection features include internal foldback current limiting, output overvoltage crowbar and optional short-circuit shutdown. Soft-start is provided by an external capacitor that can be used to properly sequence supplies. The operating current level is user-programmable via an external current sense resistor. Wide input supply range allows operation from 4V to 30V (36V maximum).FeaturesLTC1735-LTC1735-1Power GoodApplicationsNotebook and Palmtop Computers, PDAsCellular Telephones and Wireless ModemsDC Power Distribution Systems

The LTC1736 is a synchronous step-down switching regulator controller optimized for CPU power. The output voltage is programmed by a 5-bit digital-to-analog converter (DAC) that adjusts the output voltage from 0.925V to 2.00V according to Intel mobile VID specifications. The 0.8V reference is compatible with future microprocessor generations.The operating frequency (synchronizable up to 500kHz) is set by an external capacitor allowing maximum flexibility in optimizing efficiency. The output voltage is monitored by a power good window comparator that indicates when the output is within 7.5% of its programmed value.Protection features include: internal foldback current limiting, output overvoltage crowbar and optional short-circuit shutdown. Soft-start is provided by an external capacitor that can be used to properly sequence supplies. 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).Pin defeatable Burst Mode™operation provides high efficiency at low load currents. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values.ApplicationsNotebook and Palmtop Computers, PDAsPower Supply for Mobile Pentium®II and Pentium III ProcessorsLow Voltage Power Supplies