ISP1520BDGA Datasheet, PDF (10/54 Pages) NXP Semiconductors – Hi-Speed Universal Serial Bus hub controller

Philips Semiconductors
ISP1520
Hi-Speed USB hub controller
7.2.5 Hub repeater
A hub repeater manages connectivity on a per packet basis. It implements packet
signaling connectivity and resume connectivity. There are two repeaters in the ISP1520: a
Hi-Speed USB repeater and an Original USB repeater. The only major difference between
these two repeaters is the speed at which they operate. When the hub is connected to an
Original USB system, it automatically switches itself to function as an Original USB hub.
7.2.6 Hub and port controllers
The hub controller provides status report. The port controller provides control for
individual downstream facing ports; it controls the port routing module. Any port status
change will be reported to the host using the hub status change (interrupt) endpoint.
7.2.7 Bit clock recovery
The bit clock recovery circuit extracts the clock from the incoming USB data stream.
7.3 Phase-locked loop clock multiplier
A 12 MHz-to-480 MHz clock multiplier Phase-Locked Loop (PLL) is integrated on-chip.
This allows the use of low-cost 12 MHz crystals. The low crystal frequency also minimizes
EMI. No external components are required for the operation of the PLL.
7.4 I²C-bus controller
A simple serial I²C-bus interface is provided to transfer vendor ID, product ID and string
descriptor from an external I²C-bus EEPROM or microcontroller. A master/slave I²C-bus
protocol is implemented according to the timing requirements as mentioned in I²C-bus
standard specifications. The maximum data count during I²C-bus transfers for the
ISP1520 is 256 B.
7.5 Overcurrent detection circuit
An overcurrent detection circuit is integrated on-chip. The main features of this circuit are:
self reporting, automatic resetting, low-trip time and low cost. This circuit offers an easy
solution at no extra hardware cost on the board.
7.6 GoodLink
Indication of a good USB connection is provided through the GoodLink technology. An
LED can be directly connected to pin HUBGL_N through an external 330 Ω resistor.
During enumeration, the LED momentarily blinks on. After successful configuration, the
LED blinks off for 100 ms upon each transaction.
This feature provides a user-friendly indication of the status of the hub, the connected
downstream devices, and the USB traffic. It is a useful diagnostics tool to isolate faulty
USB equipment, and helps to reduce field support and hotline costs.
7.7 Power-on reset
The ISP1520 has an internal Power-On Reset (POR) circuit.
ISP1520_4
Product data sheet
Rev. 04 — 28 April 2006
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
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