saa569x NXP Semiconductors, saa569x Datasheet - Page 106

• Manufacturer Part Number: saa569x
• Description: Enhanced Tv Microcontrollers With On-screen Display Osd
• Manufacturer: NXP Semiconductors

Philips Semiconductors
30.1.1
Ports AD0 to AD7 of the microcontroller can be connected
to pins D0 to D7 of the SRAM in any order.
For the addressing, the lower group of address lines
(A0 to A8) and the upper group of address lines
(A9 to A14, A15_BK, RAMBK0 and RAMBK1) may be
connected in any order within the groups, provided that the
full 256 kbytes of external SRAM is used.
Fig.47 shows the application diagram for multipage.
When using an external SRAM smaller than 256 kbytes,
the relevant number of bits from the microcontroller
address bus should be disconnected, always removing the
most significant bits first.
For power saving modes, it might be advisable to control
the CE pin of the SRAM module(s) using one of the
microcontroller ports to de-select the SRAM.
30.1.2
Table 48 External data memory access:
Note
1. The external SRAM is intended to be used with the
2002 May 06
SYMBOL
t
t
t
t
t
t
t
t
t
t
t
RLRH
WLWH
RLDV
RHDX
RHDZ
LLWL
AVWL
QVWX
WHQX
RLAZ
WHLH
Enhanced TV microcontrollers with
On-Screen Display (OSD)
multipage software, therefore only the 12 MHz clock
microcontroller timings are provided.
A
E
see Figures 48 and 49
PPLICATION NOTES
XTERNAL DATA MEMORY ACCESS
RD pulse width
WR pulse width
RD LOW to valid data in 198
Data hold after RD
Data float after RD
ALE LOW to RD or
WR LOW
Address valid to WR
LOW or RD LOW
Data valid to WR LOW
Data hold after WR
RD LOW to address
float
RD or WR HIGH to
ALE HIGH
PARAMETER
TYPICAL
250
250
0
tbf
132
172
89
15
tbf
40
(1)
UNIT
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
106
30.1.2.1
Each timing symbol has five characters. The first character
is always ‘t’ (time). Depending on their positions, the other
characters indicate the name of a signal or the logical
status of that signal. The designations are:
A = address
C = clock
D = input data
H = logic level HIGH
I = instruction (program memory contents)
L = logic level LOW or ALE
P = PSEN
Q = output data
R = RD signal
t = time
V = valid
W = WR signal
X = no longer a valid logic level
Z = float
Examples:
– t
– t
LLPL
AVLL
= Time for ALE to PSEN LOW.
Symbol explanations
= Time for address valid to ALE LOW
SAA567x; SAA569x
Objective specification