Philips Semiconductors Product data sheet
SC28L91
3.3 V or 5.0 V Universal Asynchronous
Receiver/Transmitter (UART)

2004 Oct 21 34

X1/CLK
A1–A4
RWN
CSN
D0–D7
DTACKN
tCSC
tAS
tCS
tDF
tDAT
tDAH
tCH
tRWD
tDD
tDCR
tAH
DATA VALID
NOT
VALID
tDA
NOTE: DACKN low requires two rising edges of X1 clock after CSN is low.
SD00687

Figure 6. Bus Timing (Read Cycle) (68XXX mode)

X1/CLK
A1–A4
RWN
CSN
D0–D7
DTACKN
tCSC
tAS
tCS
tDH
tDAT
tDAH
tCH
tRWD
tDS
tDCW
tAH
NOTE: DACKN low requires two rising edges of X1 clock after CSN is low.
SD00688

Figure 7. Bus Timing (Write Cycle) (68XXX mode)

NOTE:

For Figures 6 and 7 WRN changing within the time of CEN low may cause short read or write pulses that could upset internal pointers and

registers. Bus action terminates on the rise of CEN or the fall of DACKN, which ever occurs first.