XR88C681CP Datasheet, PDF (60/99 Pages) Exar Corporation – CMOS DUAL CHANNEL UART (DUART)

XR88C681
 2! & ' '   ,1 (    #,1  $ #,< ( %
 & &( -   8I %E  (   % 
(  ( %
1 B( _/ 
 
 (% % ( %'(+&     (( - %' +  
 %(  $ '( +
  (  $($
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 (% %      $  %  
 % (  %(-   5 %(- % 8 '"   (% 
$((%( &/ +  (% %(-   +"   (  +

  (%   %
Please note that if the user were to apply this example,
he/she would be responsible for ensuring that the
incoming serial data stream is synchronous with the 1
MHz (1X) clock signal; in order to minimize bit errors
D.7 Explanation of Clock Timing Signals
  % +  (% %'( (%  !(     
%'(+('(    (( -
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  5==
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C
292
#
9
8 
2##
D
Symbol

_9:
+
_9:

_

+
_

_5
+_5
+_5  /5
+_5  5
Parameter
5.
9: 2!  8(-  9 (
5.
9:
&%  2!  E '&

 .( 2! 
'3 8(-  9
(  #, # 

 .( 2! 
'3 E '&  #,
# 
5
 $ 5
2!  8(-  9 ( 
( #," #,1" #,<  $ #,6
5
 $ 5
2!  E '&  ( #,"
#,1" #,<"  $ #,6
/5
5
Min.







Typ.
1/=/<
Max.
<
<


Units
%
8I
%
8I
%
8I
8I
Table 20. Clock Timing (Figure 13)
7"  (%  ! ( + ' +  % %
 t_CLK - X1/CLK (External) High or Low Time
    &% $& (' -('  -  ' +
(% '('(&  +" ((%  
9:  $ +
9: 
$$ ( $   %     $(' ( + '(
&  (%  M% '%   ((   
  + (    %(-  ($  -   5.
9:
( % %($    (-  $  %%
 f_CLK - X1/CLK Crystal High or Low Time
 (%  %'(+(%    - + +E '(%
(%%(    5.
9: ( " ( (  '&%
%'(  ($ 9 (  %(-   +"   %
'  & &    $ < 8I   (% ( 
 t_CTC - Counter/Timer External Clock High or Low
Time - IP2 Input
 (%  '%   ((      + (
    %(- " ( - ($    #, ( " + % &  

 .(" ' %($    (-  $  %%
Please note that this limit has no relationship with the
parameter tRTX, which is another spec associated with
the IP2 input.
 f_CTC - Counter/Timer External Clock Frequency -
IP2 Input
 (%  '%   (( +   ( 
+E '& ( - ($    #, ( " + % &  

 .(   %' %('& %%    %(- 
( +E '&   < 8I '  ($    #,
( "  $ %(  &  $$ &  
 .(
 (% %' (%  $     5"  (' %
 
/