at45db021b ATMEL Corporation, at45db021b Datasheet - Page 15

• Manufacturer Part Number: at45db021b
• Description: At45db021b 2-megabit 2.7-volt Only Dataflash
• Manufacturer: ATMEL Corporation

9. AC Waveforms
9.1
9.2
1937J–DFLSH–9/05
Waveform 1 – Inactive Clock Polarity Low and SPI Mode 0
Waveform 2 – Inactive Clock Polarity High and SPI Mode 3
Two different timing diagrams are shown below. Waveform 1 shows the SCK signal being low
when CS makes a high-to-low transition, and Waveform 2 shows the SCK signal being high
when CS makes a high-to-low transition. Both waveforms show valid timing diagrams. The setup
and hold times for the SI signal are referenced to the low-to-high transition on the SCK signal.
Waveform 1 shows timing that is also compatible with SPI Mode 0, and Waveform 2 shows tim-
ing that is compatible with SPI Mode 3.
SCK
SCK
SO
SO
CS
CS
SI
SI
HIGH IMPEDANCE
HIGH Z
t
CSS
t
t
SU
t
V
CSS
t
SU
VALID IN
t
WL
VALID IN
VALID OUT
t
WH
t
WH
t
t
V
HO
t
H
t
H
t
WL
VALID OUT
t
HO
t
CSH
t
CSH
AT45DB021B
HIGH IMPEDANCE
HIGH IMPEDANCE
t
t
t
t
DIS
DIS
CS
CS
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