IS61DDSB22M18A

IS61DDSB21M36A

Integrated Silicon Solution, Inc.- www.issi.com

Rev. B

10/03/2014

6

Power-Up and Power-Down Sequences

REF

IN

Notes:

After power and clock signals are stabilized, device can be ready for normal operation after tKC-Lock cycles. In tKC-

lock cycle period, device initializes internal logics and locks DLL. Depending on /Doff status, locking DLL will be

skipped. The following timing pictures are possible examples of power up sequence.

Sequence1. /Doff is fixed low

After tKC-lock cycle of stable clock, device is ready for normal operation.

Note) All inputs including clocks must be either logically High or Low during Power On stage. Timing above shows only one of cases.

Sequence2. /Doff is controlled and goes high after clock being stable.

Note) All inputs including clocks must be either logically High or Low during Power On stage. Timing above shows only one of cases.

Power On stage

Unstable Clock Period

Stable Clock period

Read to use

K

K#

VDD

VDDQ

VREF

VIN

Power On stage

Unstable Clock Period

Stable Clock period

Read to use

K

K#

Doff#

VDD

VDDQ

VREF

VIN

>tKC-lock for device initialization

>tKC-lock for device initialization