The MAX846A is a cost-saving multichemistry battery-charger system that comes in a space-saving 16-pin QSOP. This integrated system allows different battery chemistries (Li-Ion, NiMH or NiCd cells) to be charged using one circuit.In its simplest application, the MAX846A is a stand-alone, current-limited float voltage source that charges Li-Ion cells. It can also be paired up with a low-cost microcontroller (µC) to build a universal charger capable of charging Li-Ion, NiMH, and NiCd cells.An internal 0.5%-accurate reference allows safe charging of Li-Ion cells that require tight voltage accuracy. The voltage- and current-regulation loops used to control a low-cost external PNP transistor (or P-channel MOSFET) are independent of each other, allowing more flexibility in the charging algorithms.The MAX846A has a built-in 1%, 3.3V, 20mA linear regulator capable of powering the µC and providing a reference for the µC's analog-to-digital converters. An on-board reset notifies the controller upon any unexpected loss of power. The µC can be inexpensive, since its only functions are to monitor the voltage and current and to change the charging algorithms.ApplicationsCell PhonesDesktop Cradle ChargersHandheld Instruments (PDAs, Palmtops)Li+ Battery PacksLi+-Ion/NiMH/NiCd Multichemistry Battery ChargersNotebook Computers

The MAX745 provides all functions necessary for charging lithium-ion (Li+) battery packs. It provides a regulated charging current of up to 4A without getting hot, and a regulated voltage with only ±0.75% total error at the battery terminals. It uses low-cost, 1% resistors to set the output voltage, and a low-cost N-channel MOSFET as the power switch.The MAX745 regulates the voltage set point and charging current using two loops that work together to transition smoothly between voltage and current regulation. The per-cell battery voltage regulation limit is set between 4V and 4.4V using standard 1% resistors, and then the number of cells is set from 1 to 4 by pin-strapping. Total output voltage error is less than ±0.75%.For a similar device with an SMBus™ microcontroller interface and the ability to charge NiCd and NiMH cells, refer to the MAX1647 and MAX1648. For a low-cost Li+ charger using a linear-regulator control scheme, refer to the MAX846A.ApplicationsCell PhonesDesktop Cradle ChargersHandheld Instruments (PDAs, Palmtops)Li+ Battery PacksNotebook Computers

The MAX1259 battery manager provides backup-batteryswitching for CMOS RAM, microprocessors, or otherlow-power logic ICs. It automatically switches to thebackup battery when the primary power supply is interrupted.Low-loss switches guarantee an input-to-outputdifferential of only 200mV while supplying 250mA fromthe primary power supply or 15mA from the battery.Battery discharge during shipping does not occur in theMAX1259, since the backup battery can be disconnectedby strobing the RST input.A battery-fail output signal indicates when the backupbattery is below +2V, and a power-fail output signal indicateswhen the primary power supply is low. TheMAX1259 monitors the backup battery, warns ofimpending power failures, and switches the memory tothe battery when failures occur. The MAX1259 is pin-compatiblewith the DS1259, but consumes three timesless supply current. Commercial, extended, and militarytemperature range devices are available.ApplicationsBattery Backup for CMOS RAMComputersControllersUninterruptible Power Supplies

The LTC3625/LTC3625-1 are programmable supercapacitor chargers designed to charge two supercapacitors in series to a fixed output voltage (4.8V/5.3V or 4V/4.5V selectable) from a 2.7V to 5.5V input supply. Automatic cell balancing prevents overvoltage damage to either supercapacitor while maximizing charge rate. No balancing resistors are required.High efficiency, high charging current, low quiescent current and low minimum external parts count (one inductor, one bypass capacitor at VIN and one programming resistor) make the LTC3625/LTC3625-1 ideally suited for small form factor backup or high peak power systems.Charging current/maximum input current level is programmed with an external resistor. When the input supply is removed and/or the EN pin is low, the LTC3625/LTC3625-1 automatically enter a low current state, drawing less than 1μA from the supercapacitors.The LTC3625/LTC3625-1 are available in a compact 12‑lead 3mm × 4mm × 0.75mm DFN package.Applications Servers, RAID Systems, Mass Storage, High Current Backup Supplies Solid State Hard Drives Wireless Power Meters High Peak Power Boosted Supplies

The LTC3677-3 is a highly integrated power management IC for single-cell Li-Ion/Polymer battery applications. It includes a PowerPath manager with automatic load prioritization, a battery charger, an ideal diode, input overvoltage protection and numerous other internal protection features. The LTC3677-3 is designed to accurately charge from current limited supplies such as USB by automatically reducing charge current such that the sum of the load current and the charge current does not exceed the programmed input current limit (100mA or 500mA modes). The LTC3677-3 reduces the battery voltage at elevated temperatures to improve safety and reliability. The three step-down switching regulators and two LDOs provide a wide range of available supplies. The LTC3677-3 also includes a pushbutton input to control power sequencing and system reset. The LTC3677-3 has pushbutton timing and sequencing designed to support the SiRF Atlas IV processor. The LTC3677-3 is available in a low profile 4mm × 7mm × 0.75mm 44-pin QFN package.Applications PNDs, DMB/DVB-H, Digital/Satellite Radio, Media Players Portable Industrial/Medical Products Other USB-Based Handheld Products

The LTC4000-1 is a high voltage, high performance controller that converts many externally compensated DC/DC power supplies into full-featured battery chargers with maximum power point control. In contrast to the LTC4000, the LTC4000-1 has an input voltage regulation loop instead of the input current regulation loop.Features of the LTC4000-1’s battery charger include: accurate (±0.25%) programmable float voltage, selectable timer or current termination, temperature qualified charging using an NTC thermistor, automatic recharge, C/10 trickle charge for deeply discharged cells, bad battery detection and status indicator outputs. The battery charger also includes precision current sensing that allows lower sense voltages for high current applications.The LTC4000-1 supports intelligent PowerPath control. An external PFET provides low loss reverse current protection. Another external PFET provides low loss charging or discharging of the battery. This second PFET also facilitates an instant-on feature that provides immediate downstream system power even when connected to a heavily discharged or shorted battery.The LTC4000-1 is available in a low profile 28-lead 4mm × 5mm QFN and SSOP packages.  LTC4000 LTC4000-1 Input Voltage Regulation MPPC No Yes Input Current Monitoring Yes Yes Input Current Regulation Yes No Applications Solar Powered Battery Charger Systems Battery Charger with High Impedance Input Source, e.g., Fuel Cell or Wind Turbine Battery Equipped Industrial or Portable Military Equipments

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