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Rev. 0A | October 2022

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IS43/46LR32320C

IS43/46LR16640C

Timing Diagram

Bank/row Activation

The Active command is used to activate a row in particular bank for a subsequent Read or Write access. The value of the BA0,BA1 inputs

selects the bank, and the address provided on A0-A13 (or the highest address bit) selects the row.

Before any READ or WRITE commands can be issued to a bank within the Mobile DDR SDRAM, a row in that bank must be opened. This

is accomplished via the ACTIVE command, which selects both the bank and the row to be activated. The row remains active until a

PRECHARGE (or READ with AUTO PRECHARGE or WRITE with AUTO PRECHARGE) command is issued to the bank.

A PRECHARGE (or READ with AUTO PRECHARGE or WRITE with AUTO PRECHARGE) command must be issued before opening a different

row in the same bank.

Figure11 : tRCD, tRRD, tRC

Once a row is Open(with an ACTIVE command) a READ or WRITE command may be issued to that row, subject to the tRCD specification.

tRCD(min) should be divided by the clock period and rounded up to the next whole number to determine the earliest clock edge after the

ACTIVE command on which a READ or WRITE command can be entered.

A subsequent ACTIVE command to a different row in the same bank can only be issued after the previous active row has been

closed(precharge). The minimum time interval between successive ACTIVE commands to the same bank is defined by tRC. A subsequent

ACTIVE command to another bank can be issued while the first bank is being accessed, which results in a reduction of total row-access

overhead. The minimum time interval between successive ACTIVE commands to different banks is defined by tRRD.

Figure10 : Active command

Notes :

1. RA : Row address

2. BA : Bank address

CLK

/CLK

CKE

/CS

/RAS

/CAS

/WE

RA

BA

A0~A13

BA0, BA1

Don’t care

RD/WT

with AP

ACT

NOP

NOP

NOP

Bank a

ROW

ACT

NOP

/CLK

CLK

Command

T0

T1

T2

T3

A0-A13

BA0, BA1

COL

Bank a

T4

Ta0

Ta1

tRCD

Don’ t care

ROW

Bank b

tRRD

Bank a

ROW

ACT

tRC

Ta2

tCH

tCL

tIS

tIH

tCK