TDA8029HLSLASHC2 datasheet(40/58 Pages) PHILIPS

40 / 58 page

2003 Oct 30

Philips Semiconductors

Product speciﬁcation

Low power single card reader

TDA8029

Table 64 Description of register bits

Table 65 Clock value for an asynchronous card

BIT

SYMBOL

DESCRIPTION

7 and 6

−

Not used.

SHL

Select HIGH Level. This bit determines how the clock is stopped when bit CST = 1. If

SHL = 0, then the clock is stopped at LOW level, if SHL = 1 at HIGH level.

CST

Clock Stop. In case of an asynchronous card, bit CST deﬁnes whether the clock to the

card is stopped or not. If CST = 1, then the clock is stopped. If CST = 0, then the clock is

determined by bits AC[2:0] according to Table 65. All frequency changes are

synchronous, ensuring that no spike or unwanted pulse width occurs during changes

3SC

Synchronous Clock. In the event of a synchronous card, then pin CLK is the copy of the

value of bit SC. In reception mode, the data from the card is available to bit UR0 after a

read operation of register URR. In transmission mode, the data is written on the I/O line

of the card when register UTR has been written to.

2 to 0

AC[2:0]

Asynchronous card clock. When CST = 0, the clock is determined by the state of these

bits according to Table 65.

fint is the frequency delivered by the internal oscillator clock circuitry.

For switching from 1/nfXTAL to 1/2fint and reverse, only the bit AC2 must be changed (AC1

and AC0 must remain the same). For switching from 1/nfXTAL or 1/2fint to stopped clock

and reverse, only bits CST and SHL must be changed.

When switching from 1/nfXTAL to 1/2fint and reverse, a delay can occur between the

command and the effective frequency change on pin CLK. The fastest switch is from

1/2fXTAL to 1/2fint and reverse, the best regarding duty cycle is from 1/8fXTAL to 1/2fint and

reverse. The bit CLKSW in register MSR tells the effective switch moment.

In case of fCLK =fXTAL, the duty cycle must be ensured by the incoming clock signal on

pin XTAL1.

AC2

AC1

AC0

CLOCK

fXTAL

1/2fXTAL

1/4fXTAL

1/8fXTAL

1/2fint

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