Document Number: 002-00833 Rev. *L
Page 47 of 74
S29VS256R
S29VS128R
S29XS256R
S29XS128R
10.7
V
CC
Power-Up and Power Down
During power-up or power-down, V
CC
must always be greater than or equal to V
IO
(V
CC
V
IO
).
The device ignores all inputs until a time delay of t
VCS
has elapsed after the moment that V
CC
and V
IO
both rise above, and stay
above the minimum V
CC
and V
IO
thresholds. During t
VCS,
the device is performing power-on reset operations.
During power-down or voltage drops below V
CC
Lockout maximum (V
LKO
), the V
CC
and V
IO
voltages must drop below V
CC
Reset
(V
RST
) minimum for a period of t
PD
for the part to initialize correctly when V
CC
and V
IO
again rise to their operating ranges. If during a
voltage drop the V
CC
stays above V
LKO
maximum, the part will stay initialized and will work correctly when V
CC
is again above V
CC
minimum. If the part locks up from improper initialization, a hardware reset can be used to initialize the part correctly.
Normal precautions must be ensured for supply decoupling to stabilize the V
CC
and V
IO
power supplies. Each device in a system
should have the V
CC
and V
IO
power supplies decoupled by a suitable capacitor close to the package connections (this capacitor is
generally in the order of 0.1 μF). At no time should V
IO
be greater then 200 mV above V
CC
(V
CC
V
IO
- 200 mV).
Notes:
1. RESET# must be high after V
CC
and V
IO
are higher than V
CC
minimum.
2. V
CC
V
IO
– 200 mV during power-up.
3. V
CC
and V
IO
ramp rate could be non-linear
4. V
CC
and V
IO
are recommended to be ramped up simultaneously.
5. Not 100% tested
.
Figure 9. V
CC
Power-up Diagram.
Parameter
Description
Test Setup
Value
Unit
t
VCS
V
CC
Setup Time (Note 5)
Min
300
µs
t
VIOS
V
IO
Setup Time
Min
300
µs
t
RH
Time between RESET# (high) and CE#
(low)
Min
200
ns
V
RST
V
CC
and V
IO
Low voltage needed to ensure
initialization will occur
Min
0.7
V
t
PD
Duration of V
CC
V
RST (min)
(Note 5)
Min
10
µs
V
CC
V
IO
RESET#
t
VCS
t
VIOS
t
RH
CE#
V
CC min
V
IO min
V
IH
