MAX745

Switch-Mode Lithium-Ion Battery-Charger

±0.75% Precision Li+ Charger Delivers 4A Without Heating


Please check latest availability status for a specific part variant.

Description

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.
MAX745: Typical Operating Circuit MAX745: Typical Operating Circuit Enlarge+

Key Features

  • Charges 1 to 4 Li+ Battery Cells
  • ±0.75% Voltage-Regulation Accuracy Using 1% Resistors
  • Provides up to 4A without Excessive Heating
  • 90% Efficient
  • Uses Low-Cost Set Resistors and N-Channel Switch
  • Up to 24V Input
  • Up to 18V Maximum Battery Voltage
  • 300kHz Pulse-Width Modulated (PWM) Operation
    • Low-Noise, Small Components
  • Stand-Alone Operation—No Microcontroller Needed

Applications/Uses

  • Cell Phones
  • Desktop Cradle Chargers
  • Handheld Instruments (PDAs, Palmtops)
  • Li+ Battery Packs
  • Notebook Computers

See parametric specs for Battery Chargers (74)


Part NumberLithium Ion CellsProtected VIN
(V)
Charging VIN
(V)
Charge Rate Set byMax. ICHG
(A)
Charge TerminationCharge RegulationOper. Temp.
(°C)
Package/PinsBudgetary
Price
maxmaxSee Notes
MAX745 
1
2
3
4
2424Resistor4
Current Limit
Max. Voltage
Switchmode-40 to +85
SSOP/20
$5.31 @1k

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.

MAX745EVKIT: Evaluation Kit for the MAX745
Product Reliability Reports: MAX745.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

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 >

 
Status:
Package:
Temperature:

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