HM658512A Series
11
AC Characteristics (Ta = 0 to +70°C, VCC = 5 V ± 10%, unless otherwise noted.) (cont.)
HM658512A
-7 -8 -10
Parameter Symbol Min Max Min Max Min Max Unit Notes
Data in to end of write t
DW
20 — 20 — 25 — ns
Data in hold time for write t
DH
0— 0— 0— ns
Output active from end of write t
OW
5— 5— 5— ns2
Write to output in high-Z t
WHZ
— 20 — 20 — 25 ns 1, 2
Transition time (rise and fall) t
T
350350350ns6
Refresh command delay time t
RFD
35 — 40 — 50 — ns
Refresh precharge time t
FP
35 — 40 — 40 — ns
Refresh command pulse width for
automatic refresh
t
FAP
70 n 8 µ 80 n 8 µ 80 n 8 µ s
Automatic refresh cycle time t
FC
115 — 130 — 160 — ns
Refresh command pulse width for
self refresh
t
FAS
8— 8— 8— µs
Refresh reset time from self refresh t
RFS
600 — 600 — 600 — ns 9
Refresh period t
REF
— 32 — 32 — 32 ms 2048
cycle
Notes: 1. t
CHZ
, t
OHZ
, t
WHZ
are defined as the time at which the output achieves the open circuit condition.
2. t
CHZ
, t
CLZ
, t
OHZ
, t
OLZ
, t
WHZ
and tOW are sampled under the condition of tT = 5 ns and not 100% tested.
3. A write occurs during the overlap of low CE and low WE. Write end is defined at the earlier of
WE going high or CE going high.
4. If the CE low transition occurs simultaneously with or from the WE low transition, the output
buffers remain in high impedance state.
5. In write cycle, OE or WE must disable output buffers prior to applying data to the device and at
the end of write cycle data inputs must be floated prior to OE or WE turning on output buffers.
During this period, I/O pins are in the output state, therefore the input signals of opposite phase
to the outputs must not be applied.
6. Transition time t
T
is measured between VIH (min) and VIL (max). VIH (min) and VIL (max) are
reference levels for measuring timing of input signals.
7. After power-up, pause for more than 100 µs and execute at least 8 initialization cycles.
8. 2048 cycles of burst refresh or the first cycle of distributed automatic refresh must be executed
within 15 µs after self refresh, in order to meet the refresh specification of 32 ms and 2048
cycles.
9. At the end of self refresh, refresh reset time (t
RFS
) is required to reset the internal self refresh
operation of the RAM. During t
RFS
, CE and OE/RFSH must be kept high. If automatic refresh
follows self refresh, low transition of OE/RFSH at the beginning of automatic refresh must not
occur during t
RFS
period.