Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.NET

X  

DP8573A Datasheet(PDF) 7 Page - Texas Instruments

Click here to check the latest version.
Part # DP8573A
Description  DP8573A Real Time Clock
Download  18 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  TI1 [Texas Instruments]
Direct Link  http://www.ti.com
Logo TI1 - Texas Instruments

DP8573A Datasheet(HTML) 7 Page - Texas Instruments

Back Button DP8573A Datasheet HTML 3Page - Texas Instruments DP8573A Datasheet HTML 4Page - Texas Instruments DP8573A Datasheet HTML 5Page - Texas Instruments DP8573A Datasheet HTML 6Page - Texas Instruments DP8573A Datasheet HTML 7Page - Texas Instruments DP8573A Datasheet HTML 8Page - Texas Instruments DP8573A Datasheet HTML 9Page - Texas Instruments DP8573A Datasheet HTML 10Page - Texas Instruments DP8573A Datasheet HTML 11Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 7 / 18 page
background image
Functional Description (Continued)
READING THE CLOCK VALIDATED READ
Since clocking of the counter occurs asynchronously to
reading of the counter it is possible to read the counter
while it is being incremented (rollover) This may result in an
incorrect time reading Thus to ensure a correct reading of
the entire contents of the clock (or that part of interest) it
must be read without a clock rollover occurring In general
this can be done by checking a rollover bit On this chip the
periodic interrupt status bits can serve this function The
following program steps can be used to accomplish this
1 Initialize program for reading clock
2 Dummy read of periodic status bit to clear it
3 Read counter bytes and store
4 Read rollover bit and test it
5 If rollover occured go to 3
6 If no rollover done
To detect the rollover individual periodic status bits can be
polled The periodic bit chosen should be equal to the high-
est frequency counter register to be read That is if only
SECONDS through HOURS counters are read then the
SECONDS periodic bit should be used
READING THE CLOCK INTERRUPT DRIVEN
Enabling the periodic interrupt mask bits cause interrupts
just as the clock rolls over Enabling the desired update rate
and providing an interrupt service routine that executes in
less than 10 ms enables clock reading without checking for
a rollover
READING THE CLOCK LATCHED READ
Another method to read the clock that does not require
checking the rollover bit is to write a one into the Time Save
Enable bit (D7) of the Time Save Control Register and then
to write a zero Writing a one into this bit will enable the
clock contents to be duplicated in the Time Save RAM
Changing the bit from a one to a zero will freeze and store
the contents of the clock in Time Save RAM The time then
can be read without concern for clock rollover since inter-
nal logic takes care of synchronization of the clock Be-
cause only the bits used by the clock counters will be
latched the Time Save RAM should be cleared prior to use
to ensure that random data stored in the unused bits do not
confuse the host microprocessor This bit can also provide
time save at power failure see the Additional Supply Man-
agement Functions section With the Time Save Enable bit
at a logical 0 the Time Save RAM may be used as RAM if
the latched read function is not necessary
INITIALIZING AND WRITING TO THE
CALENDAR-CLOCK
Upon initial application of power to the TCP or when making
time corrections the time must be written into the clock To
correctly write the time to the counters the clock would
normally be stopped by writing the StartStop bit in the Real
Time Mode Register to a zero This stops the clock from
counting and disables the carry circuitry When initializing
the clock’s Real Time Mode Register it is recommended
that first the various mode bits be written while maintaining
the StartStop bit reset and then writing to the register a
second time with the StartStop bit set
The above method is useful when the entire clock is being
corrected If one location is being updated the clock need
not be stopped since this will reset the prescaler and time
will be lost An ideal example of this is correcting the hours
for daylight savings time To write to the clock ‘‘on the fly’’
the best method is to wait for the 1100 of a second period-
ic interrupt Then wait an additional 16 ms and then write
the data to the clock
PRESCALEROSCILLATOR FUNCTIONAL
DESCRIPTION
Feeding the counter chain is a programmable prescaler
which divides the crystal oscillator frequency to 32 kHz and
further to 100 Hz for the counter chain (see
Figure 3 )
TLF9981 – 8
FIGURE 3 Programmable Clock Prescaler Block
In addition to the inverter the oscillator feedback bias resis-
tor is included on chip as shown in
Figure 4 The oscillator
input may be driven from an external source if desired Re-
fer to test mode application note for details The oscillator
stability is enhanced through the use of an on chip regulated
power supply
The typical range of trimmer capacitor (as shown in Oscilla-
tor Circuit Diagram
Figure 4 and in the typical application) at
the oscillator input pin is suggested only to allow accurate
tuning of the oscillator This range is based on a typical
printed circuit board layout and may have to be changed
depending on the parasitic capacitance of the printed circuit
board or fixture being used In all cases the load capaci-
tance
specified by the crystal manufacturer (nominal value
11 pF for the 32768 crystal) is what determines proper os-
cillation This load capcitance is the series combination of
capacitance on each side of the crystal (with respect to
ground)
TLF9981 – 9
FIGURE 4 Oscillator Circuit Diagram
6


Similar Part No. - DP8573A

ManufacturerPart #DatasheetDescription
logo
National Semiconductor ...
DP8573A NSC-DP8573A Datasheet
270Kb / 16P
   Real Time Clock (RTC)
DP8573AN NSC-DP8573AN Datasheet
270Kb / 16P
   Real Time Clock (RTC)
DP8573AV NSC-DP8573AV Datasheet
270Kb / 16P
   Real Time Clock (RTC)
More results

Similar Description - DP8573A

ManufacturerPart #DatasheetDescription
logo
Dallas Semiconductor
DS1285 DALLAS-DS1285 Datasheet
21Kb / 1P
   Real Time Clock
logo
Toshiba Semiconductor
TC8521AP TOSHIBA-TC8521AP Datasheet
863Kb / 25P
   REAL TIME CLOCK ?
logo
RICOH electronics devic...
RP5C15 RICOH-RP5C15 Datasheet
137Kb / 12P
   REAL-TIME CLOCK
logo
Epson ToYoCom
RTC-63421 EPSONTOYOCOM-RTC-63421 Datasheet
413Kb / 2P
   Real time clock
logo
Golledge Electronics Lt...
RV8564C3 GOLLEDGE-RV8564C3 Datasheet
128Kb / 1P
   Real Time Clock
RV8564C2 GOLLEDGE-RV8564C2 Datasheet
62Kb / 1P
   Real Time clock
logo
List of Unclassifed Man...
VT82887 ETC1-VT82887 Datasheet
81Kb / 17P
   Real Time Clock
logo
Dallas Semiconductor
DS1287A DALLAS-DS1287A Datasheet
17Kb / 1P
   Real Time Clock
logo
Epson ToYoCom
RTC-65271 EPSONTOYOCOM-RTC-65271 Datasheet
385Kb / 2P
   Real time clock
logo
List of Unclassifed Man...
TC8250P ETC-TC8250P Datasheet
412Kb / 20P
   Real time clock
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.NET
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com