ADSP-21486KSWZ-2AB datasheet(32/68 Pages) AD

32 / 68 page

Rev. B

Page 32 of 68

March 2013

ADSP-21483/ADSP-21486/ADSP-21487/ADSP-21488/ADSP-21489

SDRAM Interface Timing (166 MHz SDCLK)

The maximum frequency for SDRAM is 166 MHz. For informa-

tion on SDRAM frequency and programming, see the

ADSP-214xx SHARC Processor Hardware Reference, Engineer-

to-Engineer Note “Interfacing SDRAM Memories to SHARC

Processors” (EE-286), and the SDRAM vendor data sheet.

Table 31. SDRAM Interface Timing

Parameter

Min

Max

Unit

Timing Requirements

tSSDAT

DATA Setup Before SDCLK

0.7

tHSDAT

DATA Hold After SDCLK

1.23

Switching Characteristics

tSDCLK

SDCLK Period

tSDCLKH

SDCLK Width High

2.2

tSDCLKL

SDCLK Width Low

2.2

tDCAD

Command, ADDR, Data Delay After SDCLK

tHCAD

Command, ADDR, Data Hold After SDCLK

tDSDAT

Data Disable After SDCLK

5.3

tENSDAT

Data Enable After SDCLK

0.3

1 Systems should use the SDRAM model with a speed grade higher than the desired SDRAM controller speed. For example, to run the SDRAM controller at 166 MHz the

SDRAM model with a speed grade of 183 MHz or above should be used. See Engineer-to-Engineer Note “Interfacing SDRAM Memories to SHARC Processors” (EE-286) for

more information on hardware design guidelines for the SDRAM interface.

2 Command pins include: SDCAS, SDRAS, SDWE, MSx, SDA10, SDCKE.

Figure 18. SDRAM Interface Timing

SDCLK

DATA (IN)

DATA (OUT)

COMMAND/ADDR

(OUT)

tSDCLKH

tSDCLKL

tHSDAT

tSSDAT

tHCAD

tDCAD

tENSDAT

tDCAD

tDSDAT

tHCAD

tSDCLK

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