EDS6432AFTA, EDS6432CFTA
Power-up Sequence
Power-up sequence
The SDRAM should be goes on the following sequence with power up.
The CLK, CKE, /CS, DQM and DQ pins keep low till power stabilizes.
The CLK pin is stabilized within 100 µs after power stabilizes before the following initialization sequence.
The CKE and DQM is driven to high between power stabilizes and the initialization sequence.
This SDRAM has VDD clamp diodes for CLK, CKE, address, /RAS, /CAS, /WE, /CS, DQM and DQ pins. If these
pins go high before power up, the large current flows from these pins to VDD through the diodes.
Initialization sequence
When 200 µs or more has past after the above power-up sequence, all banks must be precharged using the
precharge command (PALL). After tRP delay, set 8 or more auto refresh commands (REF). Set the mode register
set command (MRS) to initialize the mode register. We recommend that by keeping DQM and CKE to High, the
output buffer becomes High-Z during Initialization sequence, to avoid DQ bus contention on memory system formed
with a number of device.
Initialization sequence
Power up sequence
100 µs
200 µs
VDD, VDDQ 0 V
Low
Low
Low
CKE, DQM
CLK
/CS, DQ
Power stabilize
Power-up sequence and Initialization sequence
Data Sheet E0487E50 (Ver. 5.0)
23
ELPIDA [ ELPIDA MEMORY ]
