Analog Devices

The LTC3549 is a high efficiency, monolithic synchronous buck regulator using a constant-frequency, current mode architecture. The output voltage is adjusted via an external resistor divider.A fixed switching frequency of 2.25MHz is supported. This switching frequency allows the use of small surface mount inductors and capacitors, including ceramics.Supply current during Burst Mode operation is only 50µA dropping to < 1µA in shutdown. The 1.6V to 5.5V input voltage range makes the LTC3549 ideally suited for single cell Li-Ion, Li-Metal and 2-cell alkaline, NiCd or NiMH battery-powered applications. 100% duty cycle capability provides low dropout operation, extending battery life in portable systems. Burst Mode operation can be user-enabled, increasing efficiency at light loads, further extending battery life.The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Internal soft-start offers controlled output voltage rise time at startup without the need for external components.Applications2 AA-Cell ApplicationsCellular PhonesDigital CamerasMP3 Players

The LTC3550-1 is a standalone linear charger with a 600mA monolithic synchronous buck converter. It is capable of charging a single-cell Li-Ion battery from both wall adapter and USB inputs. The charger automatically selects the appropriate power source for charging.Internal thermal feedback regulates the battery charge current to maintain a constant die temperature during high power operation or high ambient temperature conditions. The float voltage is fixed at 4.2V and the charge currents are programmed with external resistors. The LTC3550-1 terminates the charge cycle when the charge current drops below the programmed termination threshold after the final float voltage is reached. With power applied to both inputs, the LTC3550-1 can be put into shutdown mode reducing the DCIN supply current to 20μA, the USBIN supply current to 10μA, and the battery drain current to less than 2μA.The synchronous buck converter generates a fixed output voltage of 1.875V. The switching frequency is internally set at 1.5MHz, allowing the use of small surface mount inductors and capacitors.VOUTLTC3550AdjustableLTC3550-11.875VApplicationsCellular Telephones

The LTC3552-1 is a complete constant-current/constant-voltage linear charger and dual fixed output DC/DC converter for single cell lithium-ion batteries. Its DFN package and low external component count make the LTC3552-1 ideally suited for portable applications. Furthermore, the LTC3552-1 is designed to work within USB power specifications.No external sense resistor or external blocking diode are required due to the internal MOSFET architecture. The charge voltage is fixed at 4.2V and the charge current is programmed with a resistor. The charge cycle terminates when the charge current drops below the programmed termination threshold after the final float voltage is reached. When the input supply (wall adapter or USB supply) is removed, the LTC3552-1 enters a low current state dropping the battery drain current to less than 2μA. Thermal regulation maximizes charge rate without risk of overheating.The synchronous step-down switching regulators generate fixed output voltages of 1.8V and 1.575V. The switching frequency is set at 2.25MHz, allowing the use of small surface mount inductors and capacitors.VOUTLTC3552Adjustable (0.6V to 5V)LTC3552-11.8V & 1.575VApplicationsCellular Telephones, PDAs, MP3 PlayersBluetooth Applications

The LTC3553-2 is a micropower, highly integrated power management and battery charger IC for single-cell Li-Ion/Polymer battery applications. It includes a PowerPath manager with automatic load prioritization, a battery charger, an ideal diode and numerous internal protection features. Designed specifically for USB applications, the LTC3553-2 power manager automatically limits input current to a maximum of either 100mA or 500mA. Battery charge current is automatically reduced such that the sum of the load current and the charge current does not exceed the selected input current limit. The LTC3553-2 also includes a synchronous buck regulator, an always-on low dropout linear regulator (LDO), and a pushbutton controller. With all supplies enabled in standby mode, the quiescent current drawn from the battery is only 12μA. The LTC3553-2 is available in a 3mm × 3mm × 0.75mm 20-pin QFN package.OptionsLDOPGOODHard Reset TimeLTC3553ON/OFF ControlNo5 secondsLTC3553-2Always OnYes14 secondsApplicationsUSB-Based Handheld ProductsPortable Li-Ion/Polymer Based Electronic DevicesWearable ElectronicsLow Power Medical Devices

The LTC3554 family are micropower, highly integrated power management and battery charger ICs for single-cell Li-Ion/Polymer battery applications. They include a PowerPath™manager with automatic load prioritization, a battery charger, an ideal diode and numerous internal protection features. Designed specifically for USB applications, the LTC3554 power managers automatically limit input current to a maximum of either 100mA or 500mA. Battery charge current is automatically reduced such that the sum of the load current and the charge current does not exceed the selected input current limit.The LTC3554 also includes two synchronous step-down switching regulators as well as a pushbutton controller. With all supplies enabled in standby mode, the quiescent current drawn from the battery is only 10μA. The LTC3554 family are available in a 3mm × 3mm × 0.75mm 20-lead QFN package.ApplicationsUSB-Based Handheld ProductsPortable Li-Ion/Polymer Based Electronic DevicesFitness ComputersLow Power Medical Devices

The LTC3555 family are highly integrated USB compatible power management and battery charger ICs for Li-Ion/Polymer battery applications. They include a high efficiency current limited switching PowerPath manager with automatic load prioritization, a battery charger, an ideal diode and three general purpose synchronous step-down switching regulators.The LTC3555 family limits input current to either 100mA or 500mA for USB applications or 1A for adapter-powered applications. Unlike linear chargers, the LTC3555 family’s switching architecture transmits nearly all of the power available from the USB port to the load with minimal loss and heat which eases thermal constraints in small spaces.Two of the three general purpose switching regulators can provide up to 400mA and the third can deliver 1A. The entire product can be controlled via I2C or simple I/O. The LTC3555-1/LTC3555-3 versions offer "instant-on" power delivery to the portable product even with a very low battery voltage. The LTC3555-3 version also has a reduced charger float voltage of 4.100V for battery safety and longevity.The LTC3555 family is available in the low profile 28-pin (4mm × 5mm × 0.75mm) QFN surface mount package.ApplicationsHDD-Based MP3 Players, PDAs, GPS, PMPsPortable Medical ProductsHandheld InstrumentationOther USB-Based Handheld Products

The LTC3556 is a highly integrated power management and battery charger IC for Li-Ion/Polymer battery applications. It includes a high efficiency current limited switching PowerPath manager with automatic load prioritization, a battery charger, an ideal diode, and three synchronous switching regulators (two bucks and one buck-boost). Designed specifically for USB applications, the LTC3556’s switching power manager automatically limits input current to a maximum of either 100mA or 500mA for USB applications or 1A for adapter-powered applicationsThe LTC3556’s switching input stage transmits nearly all of the 2.5W available from the USB port to the system load with minimal power wasted as heat. This feature allows the LTC3556 to provide more power to the application and eases the constraint of thermal budgeting in small spaces. The two buck regulators can provide up to 400mA each and the buck-boost can deliver 1A..The LTC3556 is available in the low profile 28-pin (4mm × 5mm × 0.75mm) QFN surface mount package.ApplicationsHDD-Based MP3 Players, PDAs, GPS, PMPsOther USB-Based Handheld Products

The LTC3557/LTC3557-1 is a highly integrated power management and battery charger IC for single cell Li-Ion/Polymer battery applications. It includes a PowerPath™manager with automatic load prioritization, a battery charger, an ideal diode and numerous internal protection features. Designed specifically for USB applications, the LTC3557/LTC3557-1 power manager automatically limits input current to a maximum of either 100mA or 500mA for USB applications or 1A for wall adapter powered applications. Battery charge current is automatically reduced such that the sum of the load current and the charge current does not exceed the programmed input current limit. The LTC3557/LTC3557-1 also includes three adjustable synchronous step-down switching regulators and a high voltage buck regulator output controller with Bat-Track that allows efficient charging from supplies as high as 38V. The LTC3557/LTC3557-1 is available in a low profile 4mm × 4mm × 0.75mm 28-pin QFN package.ApplicationsHDD-Based MP3 PlayersPDA, PMP, PND/GPSUSB-Based Handheld Products

The LTC3558 is a USB battery charger with dual high efficiency switching regulators. The device is ideally suited to power single-cell Li-Ion/Polymer based handheld applications needing multiple supply rails.Battery charge current is programmed via the PROG pin and the HPWR pin with capability up to 950mA of current at the BAT pin. TheCHRGpin allows battery status to be monitored continuously during the charging process. An internal timer controls charger termination.The part includes monolithic synchronous buck and buck-boost regulators that can provide up to 400mA of output current each and operate at efficiencies greater than 90% over the entire Li-Ion/Polymer battery range. The buck-boost regulator can regulate its programmed output voltage at its rated deliverable current over the entire Li-Ion range without drop out, increasing battery runtime.The LTC3558 is offered in a low profile (0.75mm), thermally enhanced, 20-lead (3mm × 3mm) QFN package.ApplicationsSD/Flash-Based MP3 PlayersLow Power Handheld Applications

The LTC3559/LTC3559-1 are USB battery chargers with dual high efficiency buck regulators. The parts are ideally suited to power single-cell Li-Ion/Polymer based handheld applications needing multiple supply rails.Battery charge current is programmed via the PROG pin and the HPWR pin, with capability up to 950mA at the BAT pin. The battery charger has an NTC input for temperature qualified charging. TheCHRGpin allows battery status to be monitored continuously during the charging process. An internal timer controls charger termination.Each monolithic synchronous buck regulator provides up to 400mA of output current while operating at efficiencies greater than 90% over the entire Li-Ion/Polymer range. A MODE pin provides the flexibility to place both buck regulators in a power saving Burst Mode operation or a low noise pulse skip mode.The LTC3559/LTC3559-1 are offered in a low profile thermally enhanced 16-lead (3mm × 3mm) QFN package.ApplicationsSD/Flash-Based MP3 PlayersLow Power Handheld Applications