USB5926 datasheet(36/66 Pages) MICROCHIP

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USB5926

DS00002234E-page 36



2016-2021 Microchip Technology Inc.

8.6.1

PORT CONNECTION IN GANGED MODE

Ganged Mode is enabled via SMBus or OTP configuration.

GANG_PWR becomes the port control (PRTCTL) pin for all

downstream ports when the hub is configured for ganged port power control mode. All port power controllers should be

controlled from this pin when the hub is configured for ganged port power mode. While in this mode of operation, an

over-current event on any single downstream port will cause all downstream ports to be flagged for over-current.

8.6.2

PORT CONNECTION IN INDIVIDUAL MODE

8.6.2.1

Port Power Control using USB Power Switch

Individual mode is the default mode of operation. When operating in individual mode, the device will have one port power

control and over-current sense pin for each downstream port. When disabling port power, the driver will actively drive a

'0'. To avoid unnecessary power dissipation, the pull-up resistor will be disabled at that time. When port power is

enabled, it will disable the output driver and enable the pull-up resistor, making it an open drain output. If there is an

over-current situation, the USB Power Switch will assert the open drain OCS signal. The Schmidt trigger input will rec-

ognize that as a low. The open drain output does not interfere. The over-current sense filter handles the transient con-

ditions such as low voltage while the device is powering up.

When the port is enabled, the

PRT_CTLx pin input is constantly sampled. Overcurrent events can be detected in one

of two ways:

• Single, continuous low pulse (consecutive low samples over tocs_single), as shown in Figure 8-8.

• Two short low pulses within a rolling window (two groupings of 1 or more low samples over tocs_double), as shown

in Figure 8-9.

FIGURE 8-7:

PORT POWER CONTROL WITH USB POWER SWITCH

FIGURE 8-8:

SINGLE LOW PULSE OVERCURRENT DETECTION

USB Power

Switch

50k

PRTPWR

OCS

Pull‐Up Enable

USB

Device

FILTER

PRT_CTLx

IS VIL

tocs_single

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