Dual-Input, USB/AC Adapter, 1-Cell Li+ Charger with OVP and Thermal Regulation

Dual-Input, USB/AC-Adapter 1-Cell Li+ Charger with Overvoltage Protection and Thermal Regulation

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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.
MAX1874: Typical Operating Circuit MAX1874: Typical Operating Circuit Enlarge+

Key Features

  • Charge from USB or AC Adapter
  • Automatic Switchover to AC Adapter
  • Thermal Limiting Simplifies Board Design
  • Small, High-Power 16-Pin Thin QFN Package
  • Input Protection Up to 18V
  • Soft-Start
  • Automatic Battery-to-Input Load Switch


  • Cell Phones
  • Digital Cameras
  • PDAs
  • Wireless Appliances
Part NumberLithium Ion CellsProtected VIN
Charging VIN
Charge Rate Set byMax. ICHG
Charge TerminationCharge RegulationOper. Temp.
maxmaxSee Notes
MAX1874 1186.5
Logic Input
1External ControlLinear-40 to +85
$2.00 @1k
See All Battery Chargers (74)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX1874EVKIT: Evaluation Kit for the MAX1874

Technical Documents

Reference Schematic 3241 Charging Batteries Using USB Power

Quality and Environmental Data

Product Reliability Reports: MAX1874.pdf 
Lead-Free Package Tin (Sn) Whisker Reports
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

Quality Management System >
Environmental Management System >


Related Resources

Type ID PDF Title
Reference Schematic 3241 Charging Batteries Using USB Power