AT90SCR100 datasheet(205/433 Pages) ATMEL

205 / 433 page

205

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AT90SCR100

17. USB Host Controller

The USB Smart Card Interface provides an efficient way to communicate to USB with smart

cards. AT90SCR100 embeds a USB Host Controller designed to communicate with USB smart

card the same way as another USB Host system, in addition to a USB Host Smart Card Inter-

face, with some limitations.

17.1

Features

• USB 2.0 Full Speed Peripheral with Host functions (low-speed compatbible)

• Single Device Connection

– Device load: up to 60mA

• Supports USB2.0 Electrical Conditions

• Possibility to adapt USB IC Electrical Conditions

• Handle Suspend/Resume Requests

• 168 bytes of DPRAM

• 4 Pipes, configured in the DPRAM

17.2

USB Host Smart Card Interface Description

The AT90SCR100 USB Host Interface is dedicated to USB Smart Card connection. As a conse-

quence, only D+/D- are controlled by this block and must be connected to C4 and C8 pads of the

Smart Card Interface pads (see Smart Card Port in section “Pin List Configuration” ).

The USB Host Controller needs a 48Mhz clock. To do so, it needs the PLL running and PLL Mul-

tiplexer switched to clkPLL. See “Clock System” on page 31.

Finally, to be compliant with any type of USB Smart Card, the USB Host smart card interface

supports 2 different pads set: Standard USB 2.0 pads (with 15K

Ω pull-down) and USB-IC pads

(Standard IO). For USB-IC requirements, please see section “USB-IC Design” on page 206.

Please refer to USB norm and documentation to get information on these two standards.

Finally, the AT90SCR100 can generate a VBUS 5V using the internal DC/DC. See “DC/DC Con-

verter” on page 201. But the card consumption will be limited, in this case, to the capabilities of

DC/DC converter. Anyway, the card may also be supplied by external supply voltage with more

capabilities.

The USB serial resistors are not included inside USB Smart Card Interface

hardware.

To be fully USB compliant, 2 externals serial resistors of 22

Ω must be placed on

D+ and D-.

Caution

AT90SCR100 Datasheet(PDF) 205 Page - ATMEL Corporation