Semtech Adds Small 1A Lithium-Ion Battery Charger to Miniature Charger Platform

The 30V input rating protects portable systems against hot plug overshoots and faulty charging adapters. Under-voltage lock out (UVLO) is lowered to 2.85V in the SC824 so it will work well with voltage or current-limited adapters. When charging from USB, a proprietary under-voltage limiting feature reduces the charge current as needed to prevent VBUS collapsing below 4.5V in case of a weak host or hub.

Compared to previous devices in the SC81x/SC82x family, the SC824 provides additional features including an NTC thermistor interface, multi-stage timer, and an extra indicator flag. The NTC is used to disable charging when the battery temperature falls above or below predetermined thresholds. The NTC interface may also enable or disable LDO mode when the battery is disconnected. The optional programmable multi-stage charge timer protects against a faulty battery, or terminates charging on timeout if the system load is too high to terminate charging on current. Two flags indicate valid input voltage, charger status and faults.

“Not only does our new charging platform exceed the performance one would expect from a tiny state-of-the-art battery charger,” said Karl Volk, Semtech’s marketing director for Handheld Power, “but it also integrates a host of advanced features that are rare, even among much larger competing devices thereby increasing value to our customers.”

The SC824 incorporates the preferred and safest lithium-ion charging algorithm with multiple regulation loops of constant current (CC), constant voltage (CV), and constant die junction temperature (CTj). The CTj loop greatly simplifies the thermal design considerations. A tri-level logic input selects from three modes of charging: adapter mode, USB low power mode and USB high power mode. Additional charging functions include reverse current blocking, pre-qualification of a low-voltage battery, soft-start to reduce the burden on wall adapters with poor transient response, optional float charging or top-off charging with termination, auto- or forced-recharging and open/short-circuit protection.

The SC824 is packaged in a 2x2mm lead-free MLPD package (0.6mm max. height) and complies with the European Union's Restriction on Hazardous Substances in Electrical and Electronic Equipment (RoHS) directive to meet worldwide environmental and regulatory requirements.