SLLSFW6 March 2024 ISOUSB211-Q1
ADVANCE INFORMATION
When there is no peripheral device connected to the downstream side of ISOUSB211-Q1, internal 15 kΩ pull-down resistors on DD+ and DD- pins pull the bus lines to zero, creating an SE0 state. When either the DD+ or DD- lines is pulled up higher than the VIH threshold, for a time period higher than TFILTCONN, the ISOUSB211-Q1 device treats this as a connect. The ISOUSB211-Q1 device configures internal pull-up on the upstream side to match the pull-up detected on the downstream side. After connect is detected, the ISOUSB211-Q1 device waits for a reset to be asserted by the host/hub on the upstream side. Depending on whether DD+ or DD- is pulled up at the start of reset, the speed of the ISOUSB211-Q1 repeater is set. Once set, the speed of the repeater can only be changed after a power down or disconnect event.
A high-speed (HS) capable device is attached to the ISOUSB211-Q1 device would proceed to perform high-speed handshake using chirp signaling as specified in the USB2.0 standard. This would be followed by chirp signals from the host. The ISOUSB211-Q1 device reflects these chirp signals across the barrier, including HS idle (SE0) states from downstream to upstream and vice versa. Upon successful completing of the HS handshake ISOUSB211-Q1 speed is set to High speed. Once set to high-speed, the speed of the repeater can only be changed after power down, HS disconnect event, or if the peripheral or host/hub do not perform HS handshake after a reset.