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AN·493
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AC Electrical Characteristics TA = O'Cto +70'C, Vcc = 5V ±5% (Continued)
NS16450 INS8250A
NS16550A
INS8250 INS8250-B
Symbol Parameter Conditions NS16C450 INS82C50A Units
TRANSMITTER
tHR
tlR
Delay from WR/WR (WR THR)
to Reset Interrupt
Delay from RD/RD (RD IIR) to
Reset Interrupt (THRE)
tlRS Delay from InitiallNTR Reset (Note 10)
to Transmit Start
tSI Delay from Initial Write to Interrupt (Notes 7,9)
Min Max Min Max Min Max Min Max Min Max
(Note 8) 175 175 1000 1000 1000 ns
(Note 8) 250 250 1000 1000 1000 ns
8 24 24 40 24 40 16 16
16 24 16 24 16 24 50 50
tss Delay from Stop to Next Start NA NA NA 1000 1000 ns
tSTI Delay from Stop to Interrupt (THRE) (Note 7)
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tSXA Delay from Start to TXRDY Active (Note 8)
8 8 8 8 8 8 8 8
8 NA NA NA NA
tWXI Delay from Write to TXRDY Inactive (Note 8) 195 NA NA NA NA ns
MODEM CONTROL
tMDO Delay from WR/WR (Note 8)
(WR MCR) to Output
tRIM Delay to Reset Interrupt from (Note 8)
RD/RD (RD MSR)
Baudout
Cycles
Baudout
Cycles
Baudout
Cycles
Baudout
Cycles
200 200 1000 1000 1000 ns
250 250 1000 1000 1000 ns
tSIM Delay to Set Interrupt from MODEM Input (Note 8) 250 250 1000 1000 1000 ns
Note 7: This delay will be lengthened by 1 character time, minus the last stop bit time if the transmitter interrupt delay circuit is active.
Note 8: Loading of 100 pF.
Note 9: For both the NSt 6C450 and INS82C50A the value of tSI will range from 16 to 48 baudout cycles.
Nole 10: For both the NS16C450 and the INS82C50A the value of t'RS will range from 24 to 40 baudout cycles.
NA ~ Not Applicable.