Microchip Technology

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  • UCS1003-2 USB Port Power Switch with Charger Emulation

  • Created: Oct 13, 2016

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The UCS1003-2 device is a USB port power controller that can provide up to 3A continuous current (2.85A typical) to USB charging devices. It has an overcurrent trip or constant-current limiting feature that is selectable through an external resistor at its ILIM pin or programmable via the SMBus 2.0/I2C port. Aside from overcurrent limit, the UCS1003-2 also have dynamic thermal management, latch or auto-recovery fault handling, selectable active-high/active-low enable, undervoltage/overvoltage lockout, backdrive protection, and back-voltage protection. Though the device typically operates with a 5V power supply for both chip functionalities and power switch, it also supports split supply for low power in system standby states. The UCS1003-2 comes in a 4mm by 4mm 20-pin QFN package.

The circuit shown in this reference design is used to evaluate the performance of the UCS1003-2 device under different active modes or charger emulation configurations (Dedicated Charger Emulation, Data Pass-Through, BC 1.2 SDP, CDP, or DCP). The circuit provides three power input connectors to power the UCS1003-2 device. A 5V power supply can be inserted at the DC barrel jack J6, at the screw terminal ST1, or at the USB port J9. Headers J5 and J8 just need to be populated properly to supply VS and VDD according to what power input connector/s are used. In order for the circuit to be functional, headers J7, J12, and J13 must be populated. The header J12 determines the polarity of the PWR_EN pin whether its active-high or active low, while J13 selects the current limit. The header J7 connects the VBUS pin of the UCS1003-2 device to the VBUS pin of the USB port J10. The port power switch enable/disable pin of the device (PWM_EN) is accessible through header J11. The EM_EN, M1, and M2 pins, which determine the charger emulation mode of the device, can also be accessed through header J11. The latch or auto-recovery fault-handling feature of the UCS1003-2 can be enabled or disabled through header J14. The attach/removal detection feature is also accessible via J14.

The circuit includes two LED indicators for an error event and charging status. The red LED (LED1), which is connected to ALERT# pin, turns ON if an error is detected by the UCS1003-2 device. The green LED (LED2) attached to pin CHRG# indicates that charging of an attached device is active. The output of the UCS1003-2 power switch is connected to the type A USB 2.0 port (J10). USB charging devices like smartphones, tablets, etc. can charge its internal batteries through this USB port. The UCS1003-2 supports popular emulation profiles for Apple, Samsung, and BC1.2 compliant devices.



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