The DC1138A-A contains the LTC3557 Power Management Integrated Circuit (PMIC) plus the LT3505EDD 36V (40V transients) buck regulator. The LTC3557 (4.2V charge voltage) includes a PowerPath controller, a 1.5A battery charger (configured for 500mA), an ideal diode, an always-on LDO, three synchronous step-down switching regulators (600mA and 2 × 400mA ), as well as a buck regulator VC controller.
Designed specifically for USB applications, the PowerPath controller incorporates a precision input current limit which communicates with the battery charger to ensure that the input current does not violate the USB specification. The ideal diode from BAT to VOUT guarantees that ample power is always available to VOUT even if there is insufficient or absent power at VBUS. The LTC3557 also has the ability to receive power from a wall adapter or other non-current-limited power source.