NTE21256 データシートの表示（PDF） - NTE Electronics

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NTE21256

262,144–Bit Dynamic Random Access Memory (DRAM)

NTE Electronics 

AC Characteristics: (TA = 0° to +70°C, VCC = 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

tRC

tRWC

tRAC

tCAC

tRAS

tCAS

tREF

tRP

tCRP

tRCD

tRSH

tCSH

tASR

tRAH

tASC

tCAH

tAR

tT

tRCS

tRCH

tRRH

tOFF

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. VIH and VIL are reference levels to measure timing of input signals. Also, transition times

are measured between VIH and VIL.

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 tT = 5ns for the input signals

Note12. The specification for tRC (Min), tRWC (Min), and page–mode cycle time (tPC) are only used

to indicate cycle time at which proper operation over full temperature range

(0°C ≤ TA ≤ +70°C) is assured.

Note13. Measured with a load equivalent to two TTL loads and 100pf.

Note14. Assumes that tRCD ≤ tRCD (Max). If tRCD is greater than the maximum recommended value

shown in this table, tRAC will increase by the amount that tRCD exceeds the value shown.

Note15. Assumes that tRCD ≤ tRCD (Max).

Note16. Operation within the tRCD (Max) limit ensures that tRAC (Max) can be met. tRCD (Max) is spe-

cified as a reference point only. If tRCD is greater than the specified tRCD (Max) limit, then

access time is controlled exclusively by tCAC.

Note17. tRCD + tCAH ≥ tAR Min, tRCD + tDH ≥ tDHR Min, tRCD + tWCH ≥ tWCR Min.

Note18. Either tRRH or tRCH must be satisfied for a read cycle.

Note19. tOFF (Max) defines the time at which the output achieves the open circuit condition and is not

referenced to output voltage levels.

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