ISP1123NB

ISP1123 Universal Serial Bus compound hub Rev. 01 — 5 October 1999 Preliminary specification 1. General description The ISP1123 is a compound Universal Serial Bus (USB) hub device which complies with USB Specification Rev. 1.1. It integrates a Serial Interface Engine (SIE), hub repeater, hub controller, USB data transceivers and a 3.3 V voltage regulator. It has a configurable number of downstream ports, ranging from 2 to 5, with one port dedicated to an embedded or non-removable function. The ISP1123 can be bus-powered, self-powered or hybrid-powered. When it is hybrid-powered the hub functions are powered by the upstream power supply (VBUS), but the downstream ports are powered by an external 5 Volt supply. The low power consumption in ‘suspend’ mode allows easy design of equipment that is compliant with the ACPI™, OnNow™ and USB power management requirements. The ISP1123 has built-in overcurrent sense inputs, supporting individual and ganged mode overcurrent protection for downstream ports. All ports (including the hub) have GoodLink™ indicator outputs for easy visual monitoring of USB traffic. The ISP1123 has a serial I2C-bus interface for external EEPROM access and a reduced frequency (6 MHz) crystal oscillator. These features allow significant cost savings in system design and easy implementation of advanced USB functionality into PC peripherals. 2. Features c c s High performance USB hub device with integrated hub repeater, hub controller, Serial Interface Engine (SIE),...