The low-cost MAX1873T 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 MAX1873T 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 MAX1873T may also be used as an efficient currentlimited source to charge NiCd or NiMH batteries in multichemistry charger designs. The MAX1873T is available in a space-saving 16-pin QSOP package. Use the evaluation kit (MAX1873EVKIT) to help reduce design time.