cx20493-35/app Conexant Systems, Inc., cx20493-35/app Datasheet - Page 69

• Manufacturer Part Number: cx20493-35/app
• Description: With Cx20493 Smartdaa?
• Manufacturer: Conexant Systems, Inc.

3.4.2
3.4.2.1
Table 3-18. Timing - External Memory Bus
102247B
t
t
t
t
t
t
t
t
t
t
t
t
Notes:
1.
2.
3.
4.
FI
CYC
AS
ES
RW
RDS
RDH
AS
ES
WW
WTD
WTH
CX81801-7x/8x SmartV.XX Modem in 128-Pin LQFP with CX20493 in 32-Pin LQFP Data Sheet
Symbol
ES = RAMSEL# or ROMSEL#.
Read pulse width and write pulse width:
Memory speed determination:
Output Enable to Output Delay Timing:
RAM: t
ROM: t
RAM: t ACCESS = t
ROM: t ACCESS = 4(t
RAM: t
ROM: t
RW
OE
RW
OE
Interface and Timing Waveforms
, t
= t
, t
= t
Internal Operating Frequency
Internal Operating Clock Cycle
READ# High to Address Valid
READ# High to ES Valid
READ# Pulse Width
Read Data Valid to READ# High
READ# High to Read Data Hold
WRITE# High to Address Valid
WRITE# High to ES Valid
WRITE# to WRITE# Pulse Width
WRITE# Low to Write Data Valid
WRITE# High to Write Data Hold
WW
WW
RW
RW
= 0.5 t
= 3.5 t
CYC
- t
- t
External Memory Bus Timing
The external memory bus timing is listed in Table 3-18 and illustrated in Figure 3-9.
RDS
CYC
RDS
- t
CYC
CYC
) - t
ES
= 0.5(t
= 3.5(t
Parameter
ES
- t
= 15 for Non-Extended Cycle Timing
= 105 for Extended Cycle Timing
RDS
CYC
- t
CYC
RDS
= 330 - 8 - 6.1 = 15.9 ns (i.e., use 15 ns memory)
) - t
) - t
= 4(30) - 8 - 6.1 = 105.9 ns (i.e., use 90 ns memory).
RDS
RDS
= 15 - 6.1 = 8.9 ns
= 105 - 6.1 = 98.9 ns.
Conexant
Write
Read
28.224
Min
6.1
5.0
30
15
15
–
–
0
–
–
–
Typ.
6.5
6.5
–
–
8
–
–
0
8
–
5
–
Max
105
105
8.2
11
11
–
–
9
–
8
–
–
Units
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
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