ISP1123
Universal Serial Bus compound hub
Rev. 01 鈥?5 October 1999
Preliminary speci鏗乧ation
1. General description
The ISP1123 is a compound Universal Serial Bus (USB) hub device which complies
with
USB Speci鏗乧ation 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
con鏗乬urable 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 (V
BUS
),
but the downstream ports are powered by an external 5 Volt supply. The low power
consumption in 鈥榮uspend鈥?mode allows easy design of equipment that is compliant
with the ACPI鈩? OnNow鈩?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鈩?indicator outputs for easy visual monitoring of USB traf鏗乧. The ISP1123
has a serial I
2
C-bus interface for external EEPROM access and a reduced frequency
(6 MHz) crystal oscillator. These features allow signi鏗乧ant 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), data transceivers and 3.3 V voltage regulator
s
Complies with
Universal Serial Bus Speci鏗乧ation Rev. 1.1
and ACPI, OnNow and
USB power management requirements
s
Downstream port 1 dedicated to a non-removable function, correctly reported in
the related descriptors
s
Con鏗乬urable from 2 to 5 downstream ports with automatic speed detection
s
Internal power-on reset and low voltage reset circuit
s
Supports bus-powered, hybrid-powered and self-powered application
s
Individual or global power switching for downstream ports
s
Individual or ganged port overcurrent protection with built-in sense circuits
s
6 MHz crystal oscillator with on-chip PLL for low EMI
s
Visual USB traf鏗乧 monitoring (GoodLink鈩? for hub and downstream ports
s
I
2
C-bus interface to read vendor ID, product ID and con鏗乬uration bits from
external EEPROM