TMP91C824
91C824-229
2008-02-20
4.9 Bus
Request/Bus
Acknowledge
Variable
f
FPH
=
4 MHz
f
FPH
=
16 MHz
Symbol Parameter
Min Max
Min Max
Min Max
Unit
t
ABA
Output buffer off to
BUSAK
low
0 80 0 80 0 80
ns
t
BAA
BUSAK
high to output buffer on
0 80 0 80 0 80
ns
Note 1: Even if the
BUSRQ
signal goes low, the bus will not be released while the
WAIT
signal is low.
The bus will only be released when
BUSRQ
goes low while
WAIT
is high.
Note 2: This line shows only that the output buffer is in the off state.
It does not indicate that the signal level is fixed.
Just after the bus is released, the signal level set before the bus was released is maintained
dynamically by the external capacitance. Therefore, to fix the signal level using an external
resister during bus release, careful design is necessary, since fixing of the level is delayed.
The internal programmable pull-up/pull-down resistor is switched between the active and non-
active states by the internal signal.
BUSAK
A0 to A23,
RD
,
WR
CS0
to
CS3
,
R/
W
,
HWR
ALE
AD0 to AD15
t
CBAL
t
ABA
t
BAA
(Note 2)
(Note 2)
(Note 1)
BUSRQ