The ISL6257 is a highly integrated Li-Ion/Li-Ion polymer battery charger controller designed for notebook computers. It uses a synchronous buck topology to achieve high efficiency at low system voltages. The low-side MOSFET emulates a diode at light loads to improve light load efficiency and prevent system bus boosting. The constant output voltage can be selected for 2, 3 and 4 series Li-Ion cells with ±0.5% accuracy over temperature. It can also be programmed between 4.2V + 5% per cell and 4.2V - 5% per cell to optimize battery capacity. When supplying the load and battery charger simultaneously, the input current limit for the AC adapter is programmable to within ±3% accuracy to avoid overloading the AC adapter and to allow the system to make efficient use of the available power.
The ISL6257 provides a compact solution for charging Li‑ion/Li‑polymer batteries in narrow‑VDC systems. It supports 2‑4 series cells, offers programmable charge‑voltage accuracy of ±0.5 % and input‑current limit accuracy of ±3 %, and includes features such as AC‑adapter detection, battery‑discharge MOSFET control, and thermal shutdown.
The datasheet details electrical specifications, pin functions, typical performance graphs, and layout recommendations for optimal efficiency and low noise. It also lists ordering information, absolute maximum ratings, and mechanical package dimensions for the QFN and MLFP variants.
| Input Voltage Range (DCIN) | 7 V – 25 V |
|---|---|
| Charge Voltage Accuracy | ±0.5 % |
| Input Current Limit Accuracy | ±3 % |
| Battery Leakage Current | 3 pA – 10 pA |
| Maximum Duty Cycle | 97 % – 99.6 % |
| Thermal Shutdown Temperature | 150 °C |
The device operates with an input voltage from 7 V to 25 V.
It supports charging battery packs of 2, 3, or 4 series Li‑ion cells.
The charge‑voltage accuracy is ±0.5 % over the temperature range –10 °C to +100 °C.
Thermal shutdown occurs at 150 °C.