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Dear All,
About the AN69235 of the application note,
In the red circle,this document says HX2LP can support up to THREE downstream ports.
Could you tell me why HX2LP cannot support ALL(FOUR) downstream ports with bus-power?
Regards,
Nagata
Solved! Go to Solution.
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USB Hosts Hubs Transceivers
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Hi,
The host provides 500mA for a bus powered upstream port. If a HX2LP hub is connected to the port, it's power consumption is around 230 mA (5V) as mentioned in the App Note. Now, when a device is plugged in to the downstream ports of the hub, it expects to be able to consume 100mA power in bus -powered mode.
This implies if 4 downstream ports are supported, the hub should be able to provide 400mA in total (100mA to each port). But since HX2LP itself consumes 230mA power out of the 500mA it drew from the upstream port, not enough power is left which HX2LP can provide to 4 downstream ports (400mA required). That is why, HX2LP can only support up to 3 downstream ports.
Kindly let me know if you need further clarifications.
Regards,
Mallika
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Hi,
The host provides 500mA for a bus powered upstream port. If a HX2LP hub is connected to the port, it's power consumption is around 230 mA (5V) as mentioned in the App Note. Now, when a device is plugged in to the downstream ports of the hub, it expects to be able to consume 100mA power in bus -powered mode.
This implies if 4 downstream ports are supported, the hub should be able to provide 400mA in total (100mA to each port). But since HX2LP itself consumes 230mA power out of the 500mA it drew from the upstream port, not enough power is left which HX2LP can provide to 4 downstream ports (400mA required). That is why, HX2LP can only support up to 3 downstream ports.
Kindly let me know if you need further clarifications.
Regards,
Mallika
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Hello Mallika,
Thank you for your support.
I understand it.
Regards,
Nagata
HX2VlL