Known issues with using ‘Apple USB-C Digital AV Multiport Adapter’ and ‘Apple 29W USB-C Power Adapter’ with CY4521/CY4531/CY4541 EVKs - KBA12598

Version: *A

 

Question:

What are the known issues with using ‘Apple USB-C Digital AV Multiport Adapter’ and ‘Apple 29W USB-C Power Adapter’ with CY4521/CY4531/CY4541 EVKs? 

 

Answer:

 

Issue 1: If an Apple 29W USB-C Power Adapter is connected to a Type-C port of CY4521/CY4531/CY4541 EVK through an Apple USB-C Digital AV Multiport Adapter (Apple 29W USB-C Power Adapter -> Apple USB-C Digital AV Multiport Adapter -> EVK), the voltage seen at CY4521/CY4531/CY4541’s Power Output Header (J7) is 4.5 V instead of 14.8 V, which is the expected value.

Analysis & Workaround: The issue is caused due to PD contract not getting established with 900mA Sink PDO which is required by the CY4521/CY4531/CY4541 EVK and the EVK falls back to VSafe5V. Connect the Apple 29W USB-C Power Adapter directly to the Type-C port of the EVK. The PD contract gets established at 900mA with this configuration. 

Issue 2: When Apple USB-C Digital AV Multiport Adapter is connected to the Type-C port of CY4521/CY4531/CY4541 EVK, users may see ‘Device not recognized’ message on the host (PC/Laptop). Also if a USB 2.0 device such as thumb drive is connected to the USB port of the Apple USB-C Digital AV Multiport Adapter it may not enumerate on the host.

Analysis & Workaround: When Apple USB-C Digital AV Multiport Adapter is connected to a non-Mac host, USB 2.0 devices may not get recognized. Use the USB Type-C to Type-A Adapter provided with the CY4521/CY4531/CY4541 EVK to connect the USB 2.0 device to the EVK.

Issue 3: An external monitor is connected to a PC using an Apple USB-C Digital AV Multiport Adapter and Type-C port of CY4521/CY4531/CY4541 EVK. Disconnecting and reconnecting the external monitor attached to the Apple USB-C Digital AV Multiport Adapter, may result in flickering on the external monitor. Also there may a delay before the display appears on the external monitor. 

Analysis & Workaround: When an external monitor gets connected, the Apple USB-C Digital AV Multiport Adapter sends more than one Hot Plug Detect (HPD) interrupt message to the CY4521/CY4531/CY4541 EVK. The EVK relays the same number of interrupts to the PC. The graphics card of PC takes some time to address these multiple interrupts which may cause the above mentioned flickering and delay. No workaround is available for this issue.

Issue 4: An external monitor is connected to the host (PC/Laptop) using an Apple USB-C Digital AV Multiport Adapter and Type-C port of CY4521/CY4531/CY4541 EVK. Turning off and then turning on the monitor attached to the Apple USB-C Digital AV Multiport Adapter, does not re-invoke display on the monitor consistently. 

Analysis & Workaround: When the external monitor is turned off, the Apple USB-C Digital AV Multiport Adapter occasionally does not communicate any HPD interrupt message to the CY4521/CY4531/CY4541 EVK. Therefore the EVK does not relay any HPD interrupt to the PC. The PC maintains the previous state of connected display and fails to re-establish the connection when the external monitor is actually turned on. Completely detach Apple USB-C Digital AV Multiport Adapter from the Type-C port of the EVK. Wait for the PC to remove the external display icon and then attach the Apple Adapter again. 

Issue 5: An external monitor connected to a DELL Latitude E6420 laptop using Apple USB-C Digital AV Multiport Adapter and CY4521/CY4531/CY4541 EVK. The external monitor does not invoke display for 4K screen resolution setting.

Analysis & Workaround: The Dell Latitude E6420 laptop has a graphics card which supports 4K resolution output at 30Hz vertical frequency and this specifically requires 4 lanes of Display Port multiplexer on the connecting adapter. The Apple USB-C Digital AV Multiport Adapter supports only 2 lanes of Display Port multiplexer, so the 4K resolution cannot be invoked using the Apple USB-C Digital AV Multiport Adapter for the DELL Latitude E6420 laptop. So, when the Dell Latitude E6420 laptop is connected to an external monitor using Apple USB-C Digital AV Multiport Adapter, set screen resolution to lower than 4K. 

Contact Cypress Technical Support cytechsupport@cypress.com for additional details.