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ISP1122
Universal Serial Bus stand-alone hub
Rev. 03 — 29 March 2000 Product specification
c
c
1. General description
The ISP1122 is a stand-alone 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.
The ISP1122 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 ‘suspend’ mode allows easy design of equipment that is compliant
with the ACPI™, OnNow™ and USB power management requirements.
The ISP1122 has built-in overcurrent sense inputs, supporting individual and global
overcurrent protection for downstream ports. All ports (including the hub) have
GoodLink™ indicator outputs for easy visual monitoring of USB traffic. The ISP1122
has a serial I
2
C-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
■ High performance USB hub device with integrated hub repeater, hub controller,
Serial Interface Engine (SIE), data transceivers and 3.3 V voltage regulator
■ Complies with
Universal Serial Bus Specification Rev. 1.1
and ACPI, OnNow and
USB power management requirements
■ Configurable from 2 to 5 downstream ports with automatic speed detection
■ Internal power-on reset and low voltage reset circuit
■ Supports bus-powered, hybrid-powered and self-powered application
■ Individual or ganged power switching for downstream ports
■ Individual or global port overcurrent protection with built-in sense circuits
■ 6 MHz crystal oscillator with on-chip PLL for low EMI
■ Visual USB traffic monitoring (GoodLink™) for hub and downstream ports
■ I
2
C-bus interface to read vendor ID, product ID and configuration bits from
external EEPROM
■ Operation over the extended USB bus voltage range (4.0 to 5.5 V)
■ Operating temperature range −40 to +85 °C
■ 8 kV in-circuit ESD protection for lower cost of external components