The low-cost MAX1873R/S/T provides all functions needed to simply and efficiently charge 2-, 3-, or 4-series lithium-ion cells at up to 4A or more. It provides a regulated charging current and voltage with less than ±0.75% total voltage error at the battery terminals. An external P-channel MOSFET operates in a step-down DC-DC configuration to efficiently charge batteries in low-cost designs.The MAX1873R/S/T regulates the battery voltage and charging current using two control loops that work together to transition smoothly between voltage and current regulation. An additional control loop limits current drawn from the input source so that AC adapter size and cost can be minimized. An analog voltage output proportional to charging current is also supplied so that an ADC or microcontroller can monitor charging current.The MAX1873 may also be used as an efficient current-limited source to charge NiCd or NiMH batteries in multichemistry charger designs. The MAX1873R/S/T is available in a space-saving 16-pin QSOP package. Use the evaluation kit (MAX1873EVKIT) to help reduce design time.Applications2-, 3-, or 4-Cell Li+ Battery Pack Chargers6-, 9-, or 10-Cell Li+ Battery Pack ChargersDesktop Cradle ChargersHandheld Instruments (PDAs, Palmtops)Notebook ComputersPortable Desktop Assistants (PDAs)Portable Internet Tablets

The MAX1925/MAX1926 single-cell lithium-ion (Li+) switch-mode battery chargers use an external PMOS pass element step-down configuration. Charge current is programmable, and an external capacitor sets the maximum charge time.Additional features include automatic input power detection (active-low ACON output), logic-controlled enable, and temperature monitoring with an external thermistor. The MAX1925 disables charging for inputs greater than 6.1V, while the MAX1926 charges for inputs between 4.25V and 12V.The MAX1925/MAX1926 feature two precondition levels to restore near-dead cells. The devices source 4mA to a cell that is below 2V while sourcing C/10 to a cell between 2V and 3V. Full charge current is then applied above 3V. A active-low CHG output drives an LED to indicate charging (LED on) and fault conditions (LED blinking).The MAX1925/MAX1926 are available in a 12-pin 4mm x 4mm thin QFN package and are specified over the extended temperature range (-40°C to +85°C). An evaluation kit is available to speed design.ApplicationsCradle ChargersDigital Still CamerasPDAsSelf-Charging Battery Packs

The MAX1870A step-up/step-down multichemistry battery charger charges with battery voltages above and below the adapter voltage. This highly integrated charger requires a minimum number of external components. The MAX1870A uses a proprietary step-up/stepdown control scheme that provides efficient charging. Analog inputs control charge current and voltage, and can be programmed by the host or hardwired.The MAX1870A accurately charges two to four lithiumion (Li+) series cells at greater than 4A. A programmable input current limit is included, which avoids overloading the AC adapter when supplying the load and the battery charger simultaneously. This reduces the maximum adapter current, which reduces cost. The MAX1870A provides analog outputs to monitor the current drawn from the AC adapter and charge current. A digital output indicates the presence of an AC adapter. When the adapter is removed, the MAX1870A consumes less than 1µA from the battery.The MAX1870A is available in a 32-pin thin QFN (5mm x 5mm) package and is specified over the -40°C to +85°C extended temperature range. The MAX1870A evaluation kit (MAX1870AEVKIT) is available to help reduce design time.ApplicationsHandheld TerminalsNotebook and Subnotebook Computers

The MAX1874 charges a single-cell Li+ battery from both USB and AC adapter sources. It also includes battery-to-input power switchover, so the system can be powered directly from the power source rather than from the battery.In its simplest application, the MAX1874 needs no external MOSFET or diodes, and accepts input voltages up to 6.5V; however, DC input overvoltage protection up to 18V can be added with a single SOT PFET.On-chip thermal limiting simplifies printed circuit board (PCB) layout and allows optimum charging rate without the thermal limits imposed by worst-case battery and input voltage. When the MAX1874 thermal limit is reached, the charger does not shut down but simply reduces charging current.Ambient or battery temperature can be monitored with an external thermistor. When the temperature is out of range, charging pauses.Other features include an active-low CHG output to indicate when battery current tapers below a predetermined level. DC power-OK (active-low DCOK), USB power-OK (active-low UOK), and power-on (PON) outputs indicate when valid power is present. These outputs drive logic or power-selection MOSFETs to disconnect the charging sources from the load and to protect the MAX1874 from overvoltage.The MAX1874 contains no logic for communication with the USB host. It must receive instructions from a local microcontroller. The MAX1874 is available in a 16-pin 5mm x 5mm thin QFN package and operates over the -40°C to +85°C temperature range.ApplicationsCell PhonesDigital CamerasPDAsWireless Appliances

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

Switching Power Supplies 51.38W 13.8V 3.5A 13.4V 0.23A

Switching Power Supplies 49.5W 3.3V 15A

The MAX14920/MAX14921 battery measurement analog front-end devices accurately sample cell voltages and provide level shifting for primary/secondary battery packs up to 16 cells/+65V (max). The MAX14920 monitors up to 12 cells, while the MAX14921 monitors up to 16 cells. Both devices simultaneously sample all cell voltages, allowing accurate state-of-charge and source-resistance determination. All cell voltages are level shifted to ground reference with unity gain, simplifying external ADC data conversion.The devices have a low-noise, low-offset amplifier that buffers differential voltages of up to +5V, allowing monitoring of all common lithium-ion (Li+) cell technologies. The resulting cell voltage error is ±0.5mV.The devices’ high accuracy make them ideal for monitoring cell chemistries with very flat discharge curves, such as lithium-metal phosphate.Passive-cell balancing is supported by external FET drivers. Integrated diagnostics in the devices allow open-wire detection and undervoltage/overvoltage alarms. The devices are controlled by a daisy-chainable SPI interface.The MAX14920 is available in a 64-pin (10mm x 10mm) TQFP package with an exposed pad. The MAX14921 is available in an 80-pin (12mm x 12mm) TQFP package. Both devices are specified over the -40°C to +85°C extended temperature range.Applicationse-Transportation Energy PacksEnergy Storage PacksIndustrial Battery Backup SystemsTelecom Battery Backup Systems

The MAX8895_ USB-compliant linear battery chargers operate from either a USB port or dedicated charger with automatic detection of adapter type and USB enumeration capability. The MAX8895X/MAX8895Y integrate the battery disconnect switch, current-sense circuit, MOSFET pass elements, and thermal regulation circuitry, and eliminate the external reverse-blocking Schottky diode to create the simplest and smallest stand-alone charging solutions. The MAX8895_ include an automated detection of charge adapter type, making it possible to distinguish between USB 2.0 device, USB charger, and dedicated charger devices. Furthermore, the MAX8895X/MAX8895Y include a USB enumeration function that automatically negotiates with a USB host, making it possible to achieve the highest current available from a USB 2.0 device or USB charger without processor intervention. The adapter type detection is compliant with USB 2.0 specification as well as USB charging Revision 1.1. The MAX8895_ control the charging sequence for single-cell Li+ batteries from initial power-OK indication, through prequalification, fast-charge, top-off, and finally charge termination. Charging is controlled using constant current, constant voltage, and constant die-temperature (CCCVCTj) regulation for safe operation under all conditions. The maximum charging current is adaptively controlled by subtracting the system current from the input current limit, ensuring that the charging current is always maximized for any given operating condition. The MAX8895_ feature optimized smart power control to make the best use of limited USB or adapter power. Battery charge current is set independently of the SYS_ input current limit. Power not used by the system charges the battery. Automatic input selection switches the system from battery to external power. This allows the application to operate without a battery, discharged battery, or dead battery. Other features include undervoltage lockout (UVLO), overvoltage protection (OVP), charge status flag, charge fault flag, power-OK monitor, battery thermistor monitor, charge timer, and a 3.3V output. The MAX8895_ operate from a +4.0V to +6.6V supply and include overvoltage protection up to +16V. The MAX8895_ are specified over the extended temperature range (-40°C to +85°C) and are available in a compact 2.36mm x 2.36mm, 25-bump WLP package (0.4mm pitch).ApplicationsBluetooth® HeadsetsCharging CradlesPortable Devices