SLLSFC6B November 2021 – July 2022 ISOUSB111
When there is no peripheral device connected to the downstream side of ISOUSB111, 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 ISOUSB111 device treats this as a connect. The ISOUSB111 device configures internal pull-up on the upstream side to match the pull-up detected on the downstream side. After connect is detected, the ISOUSB111 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 ISOUSB111 repeater is set. Once set, the speed of the repeater can only be changed after a power down or disconnect event.