Uart And Usb Multiplexing - Siemens SXG 75 Service Repair Documentation

16.2 UART and USB multiplexing

On the accessory connector, the differential signals (D+ and D-) of the USB interface are
multiplexed with the UART signals TX and RX.
UART/ USB multiplexing block diagram
Z1201 is a low-impedance switch which connects the accessory connector TX/RX lines either to the
PM6650 USB port, or to the MSM6250 UART. Selection is controlled by the USB_RS232_SEL1
line.
All UART lines pass through the filter Z1200 (5-Channel filter array with switches and ESD
protection) to protect the MSM6250.
Technical Documentation
TD_Repair_L3_SXG75_R1.0.pdf
Company Confidential
2006©BenQ
Release 1.0
01/2006
Page 67 of 73