NTE21256 Datasheet, PDF (4/6 Pages) NTE Electronics – 262,144-Bit Dynamic Random Access Memory (DRAM)

AC Characteristics: (T_A = 0° to +70°C, V_CC = 5V ±10%, Note 9, Note 10, Note 11 unless
otherwise specified)
Parameter
Random Read or Write Cycle Time
Read–Modify–Write Cycle Time
Access Time from RAS
Access Time from CAS
RAS Pulse Width
CAS Pulse Width
Refresh Period
RAS Precharge Time
CAS to RAS Precharge Time
RAS to CAS Delay Time
RAS Hold Time
CAS Hold Time
Row Address Setup Time
Row Address Hold Time
Column Address Setup Time
Column Address Hold Time
Column Address Hold Time referenced to RAS
Transition Time (Rise and Fall)
Read Command Setup Time
Read Command Hold Time referenced to CAS
Read Command Hold Time referenced to RAS
Output Buffer Turn–Off Delay
Symbol Test Conditions
t_RC
t_RWC
t_RAC
t_CAC
t_RAS
t_CAS
t_REF
t_RP
t_CRP
t_RCD
t_RSH
t_CSH
t_ASR
t_RAH
t_ASC
t_CAH
t_AR
t_T
t_RCS
t_RCH
t_RRH
t_OFF
Note 12
Note 12
Notes 13, Note 14
Notes 13, Note 15
Note 16
Note 17
Note 9
Note 18
Note 18
Note 19
Min Typ Max Unit
260 – – ns
310 – – ns
– – 150 ns
– – 75 ns
150 – 10⁴ ns
75 – – ns
– – 4 ms
100 – – ns
0 – – ns
30 – 75 ns
75 – – ns
150 – – ns
0 – – ns
20 – – ns
0 – – ns
30 – – ns
105 – – ns
3 – 50 ns
0 – – ns
0 – – ns
10 – – ns
0 – 40 ns
Note 9. V_IH and V_IL are reference levels to measure timing of input signals. Also, transition times
are measured between V_IH and V_IL.
Note10. An initial pause of 200µs is required after power–up followed by a minimum of eight initialization
cycles prior to normal operation.
Note 11. The time parameters specified here are valid for a transition time of t_T = 5ns for the input signals
Note12. The specification for t_RC (Min), t_RWC (Min), and page–mode cycle time (t_PC) are only used
to indicate cycle time at which proper operation over full temperature range
(0°C ≤ T_A ≤ +70°C) is assured.
Note13. Measured with a load equivalent to two TTL loads and 100pf.
Note14. Assumes that t_RCD ≤ t_RCD (Max). If t_RCD is greater than the maximum recommended value
shown in this table, t_RAC will increase by the amount that t_RCD exceeds the value shown.
Note15. Assumes that t_RCD ≤ t_RCD (Max).
Note16. Operation within the t_RCD (Max) limit ensures that t_RAC (Max) can be met. t_RCD (Max) is spe-
cified as a reference point only. If t_RCD is greater than the specified t_RCD (Max) limit, then
access time is controlled exclusively by t_CAC.
Note17. t_RCD + t_CAH ≥ t_AR Min, t_RCD + t_DH ≥ t_DHR Min, t_RCD + t_WCH ≥ t_WCR Min.
Note18. Either t_RRH or t_RCH must be satisfied for a read cycle.
Note19. t_OFF (Max) defines the time at which the output achieves the open circuit condition and is not
referenced to output voltage levels.