GMS90C320
OCT. 2000 Ver 1.2
23
1)
Capacitive loading on ports 0 and 2 may cause spurious noise pulses to be superimposed on the V
O L
of ALE and port 3. The
noise is due to external bus capacitance discharging into the port 0 and port 2 pins when these pins make 1-to-0 transitions
during bus operation. In the worst case (capacitive loading:
>
50pF at 3.3V,
>
100pF at 5V), the noise pulse on ALE line may
exceed 0.8V. In such cases it may be desirable to qualify ALE with a schmitt-trigger, or use an address latch with a schmitt-
trigger strobe input.
2)
Capacitive loading on ports 0 and 2 may cause the V
O H
on ALE and PSEN to momentarily fall below the 0.9V
C C
specification
when the address lines are stabilizing.
3)
I
C C m ax
at other frequencies is given by:
active mode: I
C C
= 1.0
× ƒ
O SC
+ 3.16
idle mode: I
C C
= 0.37
× ƒ
O SC
+ 3.63
where
ƒ
O SC
is the oscillator frequency in MHz. I
C C
values are given in mA and measured at V
C C
= 5V.
4)
I
C C
(active mode) is measured with:
XTAL1 driven with t
C LC H
, t
C H C L
= 5ns, V
IL
= V
SS
+ 0.5V, V
IH
= V
C C
- 0.5V; XTAL2 = N.C.;
EA = Port 0 = RESET = V
C C
; all other pins are disconnected. I
C C
would be slightly higher if a crystal oscillator is used (appr.
1mA).
5)
I
C C
(Idle mode) is measured with all output pins disconnected and with all peripherals disabled;
XTAL1 driven with t
C LC H
, t
C H C L
= 5ns, V
IL
= V
SS
+ 0.5V, V
IH
= V
C C
- 0.5V; XTAL2 = N.C.;
RESET = EA = V
SS
; Port0 = V
C C
; all other pins are disconnected;
6)
I
PD
(Power Down Mode) is measured under following conditions:
EA = Port 0 = V
C C
; RESET = V
SS
; XTAL2 = N.C.; XTAL1 = V
S S
; all other pins are disconnected.
