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AN-1365
APPLICATION NOTE
One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
AD1933/AD1934/AD1938/AD1939/AD1974 Boot Up Application
by David M. Thibodeau
Rev. 0 | Page 1 of 10
INTRODUCTION
The AD1933/AD1934/AD1938/AD1939/AD1974 family of
codecs, ADCs, and DACs have a standalone mode of operation
that allows them to be used without a microcontroller. Unfortu-
nately, with the exception of the ADCs being a master or a slave,
there are no options for different modes of operation in the
standalone mode. Modern systems require faster sample rates,
or TDM modes of operation, more frequently. It is desirable
to be able to have converters boot up on their own in these
advanced modes of operation where a system microcontroller
is not present. This application note details a low cost solution
for booting up these parts in any desired mode of operation.
For this example, a Microchip® PIC12(L)F1571/PIC12(L)F1572
is used to boot up the AD1938 and also provides for a mute
function. This part is very low cost and is available through
normal distribution channels. It is offered in a variety of
packages to meet the cost/size needs of most applications.
For ease of reading, this application note uses the AD1938 as
an example in the boot up application, but the application is
functional with the entire AD1933/AD1934/AD1938/AD1939/
AD1974 family.
The programming examples were written using the Custom
Computer Services, Inc. (CCS) C language compiler.
This application note details the hardware and software used to
provide this functionality.
