USB82640 datasheet(21/64 Pages) MICROCHIP

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 2010-2015 Microchip Technology Inc.

DS60001312A-page 21

USB82640

7.0

CONFIGURATION OPTIONS

7.1

Hub

Microchip’s USB 2.0 hub is fully compliant with the Universal Serial Bus 2.0 Specification [1]. See Chapter 11 (Hub

Specification) for general details regarding hub operation and functionality.

The hub provides 1 Transaction Translator (TT) that is shared by both downstream ports defined as a single-TT config-

uration. The TT contains 4 non-periodic buffers.

7.1.1

HUB CONFIGURATION OPTIONS

The Microchip hub supports a large number of features (some are mutually exclusive), and must be configured in order

to correctly function when attached to a USB host controller. There are two principal ways to configure the hub:

• internal default settings

• use settings stored on an external EEPROM or SPI Flash device

7.1.1.1

Power Switching Polarity

The hub will only support active high power controllers.

7.1.2

VBUS DETECT

According to Section 7.2.1 of the USB 2.0 Specification [1], a downstream port can never provide power to its D+ or D-

pull-up resistors unless the upstream port’s VBUS is in the asserted (powered) state. The VBUS_DET pin on the hub

monitors the state of the upstream VBUS signal and will not pull-up the D+ resistor if VBUS is not active. If VBUS goes

from an active to an inactive state (not powered), the hub will remove power from the D+ pull-up resistor within 10 sec-

onds.

7.2

Card Reader

The Microchip USB82640 is fully compliant with the following flash media card reader specifications:

• Secure Digital 2.0/MultiMediaCard Specification 4.2

- SDSC, SDHC

- TransFlashTM and reduced form factor media

- 1/4/8 bit MMC 4.2

- Supports storage addressability of up to 2 TB

• Memory Stick Specification 1.43

• Memory Stick PRO Format Specification 1.02

• Memory Stick PRO-HG Duo Format Specification 1.01

- Memory Stick, MS Duo, HS-MS, MS Pro-HG, MS Pro

7.3

System Configurations

7.3.1

EEPROM/SPI INTERFACE

The USB82640 can be configured via a 2-wire (I2C) EEPROM (512x8) or an external SPI flash device containing the

firmware for the USB82640. If an external configuration device (NVSTORE) does not exist, the internal default values

will be used. If one of the external devices is used for configuration, the OEM can update the values through the USB

interface.

The USBDM tool set is available in the Hub Card reader combo software release package.

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