USB2504/USB2504A

DS000002250A-page 4

 2007 - 2016 Microchip Technology Inc.

1.0

INTRODUCTION

The Microchip 4-Port Hub is fully compliant with the USB 2.0 Specification and will attach to a USB host as a Full-Speed

Hub or as a Full-/High-Speed Hub. The 4-Port Hub supports Low-Speed, Full-Speed, and High-Speed (if operating as

a High-Speed Hub) downstream devices on all of the enabled downstream ports.

A dedicated Transaction Translator (TT) is available for each downstream facing port. This architecture ensures maxi-

mum USB throughput for each connected device when operating with mixed-speed peripherals.

and to limit current and sense over-current conditions.

All required resistors on the USB ports are integrated into the Hub. This includes all series termination resistors on D+

and D– pins and all required pull-down and pull-up resistors on D+ and D– pins. The over-current sense inputs for the

downstream facing ports have internal pull-up resistors.

Throughout this document the upstream facing port of the hub will be referred to as the upstream port, and the down-

stream facing ports will be called the downstream ports.

1.1

OEM Selectable Features

A default configuration is available in the USB2504/USB2504A following a reset. This configuration may be sufficient

for some applications. Strapping option pins make it possible to modify a limited sub-set of the configuration options.

The USB2504/USB2504A may also be configured by an external EEPROM or a microcontroller. When using the micro-

controller interface, the Hub appears as an SMBus slave device. If the Hub is pin-strapped for external EEPROM con-

figuration but no external EEPROM is present, then a value of ‘0’ will be written to all configuration data bit fields (the

hub will attach to the host with all ‘0’ values).

The 4-Port Hub supports several OEM selectable features:

• Operation as a Self-Powered USB Hub or as a Bus-Powered USB Hub.

• Operation as a Dynamic-Powered Hub (Hub operates as a Bus-Powered device if a local power source is not

available and switches to Self-Powered operation when a local power source is available).

• Multiple Transaction Translator (Multi-TT) or Single-TT support.

SMBus Host.

• Port power switching on an individual or ganged basis.

• Port over-current monitoring on an individual or ganged basis.

• LED indicator support.

• Compound device support (port is permanently hardwired to a downstream USB peripheral device).

• Hardware strapping options enable configuration of the following features.

- Non-Removable Ports

- Port Power Polarity (active high or active low logic)

- Port Disable

- LED support

- MTT enable

- Ganged Vs Port power switching and over-current sensing