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 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 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 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 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

Audio Transformers / Signal Transformers AUDIO XFMR 200Kct:1Kct 10mW ENCAPSULATED PCB MOUNT/SP-4

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

The MAX8903A–MAX8903E/MAX8903G/MAX8903H/MAX8903J/MAX8903N/MAX8903Y are integrated 1-cell Li+ chargers and Smart Power Selectors™ with dual (AC adapter and USB) power inputs. The switch mode charger uses a high switching frequency to eliminate heat and allow tiny external components. It can operate with either separate inputs for USB and AC adapter power, or from a single input that accepts both. All power switches for charging and switching the load between battery and external power are included on-chip. No external MOSFETs, blocking diodes, or current-sense resistors are required.The MAX8903_ feature optimized smart power control to make the best use of limited USB or adapter power. Battery charge current and SYS output current limit are independently set. Power not used by the system charges the battery. Charge current and SYS output current limit can be set up to 2A while USB input current can be set to 100mA or 500mA. Automatic input selection switches the system from battery to external power. The DC input operates from 4.15V to 16V with up to 20V protection, while the USB input has a range of 4.1V to 6.3V with up to 8V protection.The MAX8903_ internally block current from the battery and system back to the DC and USB inputs when no input supply is present. Other features include prequal charging and timer, fast charge timer, overvoltage protection, charge status and fault outputs, power-OK monitors, and a battery thermistor monitor. In addition, on-chip thermal limiting reduces battery charge rate and AC adapter current to prevent charger overheating. The MAX8903_ is available in a 4mm x 4mm, 28-pin thin QFN package.The various versions of the MAX8903_ allow for design flexibility to choose key parameters such as system regulation voltage, battery prequalification threshold, and battery regulation voltage. The MAX8903B/MAX8903E/MAX8903G also includes power-enable on battery detection. See the Selector Guide section in the full data sheet for complete details.ApplicationsMobile Internet DevicesPDA, Palmtop, and Wireless HandheldsPersonal Navigation DevicesPortable Multimedia PlayersSmart Cell PhonesUltra Mobile PCs

The MAX8903A–MAX8903E/MAX8903G/MAX8903H/MAX8903J/MAX8903N/MAX8903Y are integrated 1-cell Li+ chargers and Smart Power Selectors™ with dual (AC adapter and USB) power inputs. The switch mode charger uses a high switching frequency to eliminate heat and allow tiny external components. It can operate with either separate inputs for USB and AC adapter power, or from a single input that accepts both. All power switches for charging and switching the load between battery and external power are included on-chip. No external MOSFETs, blocking diodes, or current-sense resistors are required.The MAX8903_ feature optimized smart power control to make the best use of limited USB or adapter power. Battery charge current and SYS output current limit are independently set. Power not used by the system charges the battery. Charge current and SYS output current limit can be set up to 2A while USB input current can be set to 100mA or 500mA. Automatic input selection switches the system from battery to external power. The DC input operates from 4.15V to 16V with up to 20V protection, while the USB input has a range of 4.1V to 6.3V with up to 8V protection.The MAX8903_ internally block current from the battery and system back to the DC and USB inputs when no input supply is present. Other features include prequal charging and timer, fast charge timer, overvoltage protection, charge status and fault outputs, power-OK monitors, and a battery thermistor monitor. In addition, on-chip thermal limiting reduces battery charge rate and AC adapter current to prevent charger overheating. The MAX8903_ is available in a 4mm x 4mm, 28-pin thin QFN package.The various versions of the MAX8903_ allow for design flexibility to choose key parameters such as system regulation voltage, battery prequalification threshold, and battery regulation voltage. The MAX8903B/MAX8903E/MAX8903G also includes power-enable on battery detection. See the Selector Guide section in the full data sheet for complete details.ApplicationsMobile Internet DevicesPDA, Palmtop, and Wireless HandheldsPersonal Navigation DevicesPortable Multimedia PlayersSmart Cell PhonesUltra Mobile PCs