AT90SCR100 datasheet(201/433 Pages) ATMEL

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AT90SCR100

16. DC/DC Converter

16.1

Overview

The AT90SCR100 embeds a DC/DC converter to generate voltage to supply any kind of

ISO7816 Smart Card, and to generate the VBUS voltage for USB Smart Cards.

This peripheral is also controlled by “Smart Card Interface Block (SCIB)” .

16.2

Features

• Operating Voltages : 2.7 - 5.5 V

• Programmable Ouput Voltages : 1.8V, 3V or 5V

• Automatic deactivation sequence when switched off

16.3

Description

The Smart Card voltage (CVcc) is supplied by the integrated DC/DC converter which is con-

trolled by several registers:

• The DCCR register controls the start-up, shutdown of DC/DC peripheral. See “DCCR -

DC/DC Converter Register” on page 203.

• The SCICR register controls the CVcc level by means of VCARD[1..0] bits. See “SCICR -

Smart Card Interface Control Register” on page 190.

• The SCCON register controls the generation of by means of CARDVCC bit. See “SCCON -

Smart Card Contacts Register” on page 192.

The CVcc cannot be generated while the CPRES pin remains inactive. If CPRES pin becomes

inactive while the DC/DC converter is operating, an automatic power_off sequence of the

DC/DC converter is initiated by the internal logic.

16.3.1

Initialization Procedure

To generate a specific voltage on CVcc, please follow at the following diagram:

It is mandatory to switch off the DC/DC Converter before entering in Power-down

mode, by clearing DCCR.DCON.

Note

To generate a VBUS voltage to supply a USB Smart Card, the below process is

mandatory, with SCICR.VCARD = b11, to generate 5V.

The 3.3V of CC4/CC8 will be generate using a specific regulator.

Caution

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