USB7002SLASHKDX datasheet(35/56 Pages) MICROCHIP

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DS00002670G-page 35

USB7002

8.2.1.1

Port Power Control Using Poly Fuse

When using the device with a poly fuse, there is no need for an output power control. A single port power control and

over-current sense for each downstream port is still used from the Hub's perspective. When disabling port power, the

driver will actively drive a '0'. This will have no effect as the external diode will isolate pin from the load. When port power

is enabled, it will disable the output driver and enable the pull-up resistor. This means that the pull-up resistor is providing

3.3 volts to the anode of the diode. If there is an over-current situation, the poly fuse will open. This will cause the cath-

ode of the diode to go to 0 volts. The anode of the diode will be at 0.7 volts, and the Schmidt trigger input will register

this as a low resulting in an over-current detection. The open drain output does not interfere.

8.3

CC Pin Orientation and Detection

The device provides CC1 and CC2 pins on all Type-C ports for cable plug orientation and detection of a USB Type-C

receptacle. The device also integrates a comparator and DAC circuit to implement Type-C attach and detach functions,

which supports up to eight programmable thresholds for attach detection between a UFP and DFP. When operating as

a UFP, the device supports detecting changes in the DFP’s advertised thresholds. Default nominal values for the thresh-

olds detected by the CC comparator are:

•0.20 V

•0.40 V

•0.66 V

•0.80 V

•1.23 V

•1.60 V

•2.60 V

When operating as a DFP, the device implements current sources to advertise current charging capabilities on both CC

pins. When a UFP connection is established, the current driven across the CC pins creates a voltage across the UFP’s

Rd pull-down that can be detected by the integrated CC comparator. When connected to an active cable, an alternative

pull-down, Ra, appears on the CC pin.

When operating as a UFP, the device applies an Rd pull-down on both CC lines and waits for a DFP connection from

the assertion of VBUS. The CC comparator is used to determine the advertised current charger capabilities supported

by the DFP.

FIGURE 8-3:

PORT POWER CONTROL USING A POLY FUSE

PRT_CTLx

50k

PRTPWR

OCS

USB

Device

Pull-Up Enable

Poly Fuse

FILTER

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