SAA7740 datasheet(13/28 Pages) PHILIPS

13 / 28 page

1997 May 30

Philips Semiconductors

Product speciﬁcation

Digital Audio Processing IC (DAPIC)

SAA7740H

Improper acknowledge generated by the DAPIC

If an I2C-bus device, other than DAPIC, is addressed by the master then the DAPIC will generate a short acknowledge

pulse. The DAPIC starts pulling down the SDA line at the trailing edge of the SCL clock pulse. and releases the SDA line

approximately 390 ns after the leading edge of the following SCL LOW-to-HIGH transition (see Fig.8).

This improper acknowledge pulse can cause the I2C-bus master to detect an incorrect acknowledgement, depending on

the capturing moment of the SDA line by the I2C-bus master. Any possible non-acknowledgements of involved I2C-bus

devices, including the SAA7740H, will be masked thus making the system unreliable.

To avoid these problems the I2C-bus master should only capture the SDA line at such a moment that the improper

acknowledge pulse will not be detected.

Fig.8 Improper acknowledge generated by the DAPIC.

handbook, full pagewidth

MGK425

data output

from DAPIC

SCL from

master

START condition

data output

from transmitter

390 ns (typ)

non-DAPIC device address

improper acknowledge

generated by DAPIC

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