PD488588FF datasheet(23/79 Pages) ELPIDA

23 / 79 page

Data Sheet

E0251N20 (Ver. 2.0)

µµµµPD488588FF-C80-40

12. Precharge Mechanisms

Figure 12-1 shows an example of precharge with the ROWR packet mechanism. The PRER command must occur

a time tRAS after the ACT command, and a time tRP before the next ACT command. This timing will serve as a

baseline against which the other precharge mechanisms can be compared.

Figure 12-1 Precharge via PRER Command in ROWR Packet

CTM/CFM

DQA8..0

DQB8..0

COL4

..COL0

ROW2

..ROW0

T12

T13

T10

T14

T11

T15 T16

T20

T24

T28

T17

T21

T25

T29

T18

T22

T26

T30

T19

T23

T27

T31 T32

T36

T40

T44

T33

T37

T41

T45

T34

T38

T42

T46

T35

T39

T43

T47

ACT a0

PRER a5

tRAS

tRC

a0 = {Da,Ba,Ra}

a5 = {Da,Ba}

b0 = {Da,Ba,Rb}

tRP

ACT b0

Figure 12-2 (top) shows an example of precharge with a RDA command. A bank is activated with an ROWA packet

on the ROW pins. Then, a series of four dualocts are read with RD commands in COLC packets on the COL pins.

The fourth of these commands is a RDA, which causes the bank to automatically precharge when the final read has

finished. The timing of this automatic precharge is equivalent to a PRER command in an ROWR packet on the ROW

pins that is offset a time tOFFP from the COLC packet with the RDA command. The RDA command should be treated

as a RD command in a COLC packet as well as a simultaneous (but offset) PRER command in an ROWR packet

when analyzing interactions with other packets.

Figure 12-2 (middle) shows an example of precharge with a WRA command. As in the RDA example, a bank is

activated with an ROWA packet on the ROW pins. Then, two dualocts are written with WR commands in COLC

packets on the COL pins. The second of these commands is a WRA, which causes the bank to automatically

precharge when the final write has been retired. The timing of this automatic precharge is equivalent to a PRER

command in an ROWR packet on the ROW pins that is offset a time tOFFP from the COLC packet that causes the

automatic retire. The WRA command should be treated as a WR command in a COLC packet as well as a

simultaneous (but offset) PRER command in an ROWR packet when analyzing interactions with other packets. Note

that the automatic retire is triggered by a COLC packet a time tRTR after the COLC packet with the WR command

unless the second COLC contains a RD command to the same device. This is described in more detail in Figure 15-

Figure 12-2 (bottom) shows an example of precharge with a PREX command in an COLX packet. A bank is

activated with an ROWA packet on the ROW pins. Then, a series of four dualocts are read with RD commands in

COLC packets on the COL pins. The fourth of these COLC packets includes an COLX packet with a PREX

command. This causes the bank to precharge with timing equivalent to a PRER command in an ROWR packet on

the ROW pins that is offset a time tOFFP from the COLX packet with the PREX command.

PD488588FF датащи(PDF) 23 Page - Elpida Memory

PD488588FF датащи(HTML) 23 Page - Elpida Memory

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79

датащи скачать

ссылки URL