SGM41518

The SGM41518 is a battery charger and system power path management device with integrated converter and power switches for using with single-cell Li-Ion or Li-polymer batteries. This highly integrated 1.26A device is capable of fast charging and supports a wide input voltage range suitable for wearable and earphone applications. I²C programming makes it a very flexible powering and charger design solution.

The device includes four main power switches: input reverse blocking FET (RBFET, Q1), high-side switching FET for Buck or Boost mode (HSFET, Q2), low-side switching FET for Buck or Boost mode (LSFET, Q3) and battery FET that controls the interconnection of the system and battery (BATFET, Q4). The bootstrap diode for the high-side gate driving is also integrated. The internal power path has a very low impedance that reduces the charging time and maximizes the battery discharge efficiency. Moreover, the input voltage and current regulations provide maximum charging power delivery to the battery with various types of input sources.

A wide range of input sources are supported, including standard USB hosts, charging ports and USB compliant high voltage adapters. The SGM41518 is USB 2.0 and USB 3.0 power specifications compliant with input current and voltage regulation. This limit is determined by the detection circuit in the system (e.g. USB PHY).

The SGM41518 is capable of boosting the battery voltage to supply 5V (adjustable 4.85V/5V/5.15V/5.3V) on PMID. The Boost mode is used to charge another battery by the control of PMID_GD. The PMID_GD pin is used to drive an external P-MOSFET to disconnect Boost output PMID from attached accessories.

The system voltage is regulated slightly above the battery voltage by the power path management circuit and is kept above the programmable minimum system voltage (3.5V by default). Therefore, system power is maintained even if the battery is completely depleted or removed. Dynamic power management (DPM) feature is also included that automatically reduces the charge current if the input current or voltage limit is reached. If the system load continues to increase after reduction of charge current down to zero, the power path management provides the deficit from battery by discharging battery to the system until the system power demand is fulfilled. This is called supplement mode, which prevents the input source from overloading.

Starting and termination of a charging cycle can be accomplished without software control. The sensed battery voltage is used to decide for starting phase of charging in one of the three phases of charging cycle: pre-conditioning, constant current or constant voltage. When the charge current falls below a preset limit and the battery voltage is above recharge threshold, the charger function will automatically terminate and end the charging cycle. If the voltage of a charged battery falls below the recharge threshold, the charger begins another charging cycle.

Several safety features are provided in the SGM41518 such as over-voltage and over-current protections, battery temperature monitoring, charging safety timing, thermal shutdown and input UVLO. TS pin is connected to an NTC thermistor for battery temperature monitoring and protection in both charge and Boost modes according to JEITA profile. This device also features thermal regulation in which the charge current is reduced, if the junction temperature exceeds 80℃ or 120℃ (selectable).

Charging status is reported by the STAT output and fault/status bits. A negative pulse is sent to the nINT output pin as soon as a fault occurs to notify the host. BATFET reset control is provided by nQON pin to exit ship mode or for a full system reset.

The SGM41518 is available in a Green WLCSP-2.0×2.4-30B package.