MAX1870A

19-3243; Rev 0; 4/04 KIT ATION EVALU LE B A IL A AV Step-Up/Step-Down Li+ Battery Charger Features ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ Patented Step-Up/Step-Down Control Scheme* ±0.5% Charge-Voltage Accuracy ±9% Charge-Current Accuracy ±8% Input Current-Limit Accuracy Programmable Maximum Battery Charge Current Analog Inputs Control Charge Current, Charge Voltage, and Input Current Limit Analog Output Indicates Adapter Current Input Voltage from 8V to 28V Battery Voltage from 0 to 17.6V Charges Li+ or NiCd/NiMH Batteries Tiny 32-Pin Thin QFN (5mm x 5mm) Package General Description 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 con...