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Electrical Characteristics
MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
23-8
Freescale Semiconductor
23.3.3
Processor Bus Output Timing Specifications
lists processor bus output timings.
NOTE
Above 48 MHz, the memory bus may need to be configured for one wait
state. It is the responsibility of the user to determine the actual frequency at
which to insert a wait state since this depends on the access time of SRAM
or SDRAM used in a particular system implementation.
Wait states are inserted for SRAM accesses by programming bits 6–2 of the
chip select option registers.
A wait state is added for SDRAM read accesses by setting bit 4 of the
SDRAM control register.
Table 23-8. Processor Bus Output Timing Specifications
Name
Characteristic
1
1
All timing references to SDCLK are given to its rising edge when bit 3 of the SDRAM control register is 0.
0–66 MHz
Unit
Min
Max
Control Outputs
B6a
SDCLK to chip selects (CS[6:0]) valid
—
12
nS
B6b
SDCLK to byte enables (BS[3:0]) valid
—
9.5
nS
B6c
SDCLK to output enable (OE) valid
—
9.0
nS
B6d
SDCLK to write enable (R/W) valid
—
8
nS
B6e
SDCLK to reset output (RSTO) valid
—
13.5
nS
B7a
SDCLK to control output (CS[6:0], OE) invalid (output hold)
1.5
—
nS
B7b
SDCLK to control output (BS[3:0], R/W) invalid (output hold)
1.0
—
nS
B7c
SDCLK to reset output (RSTO) invalid (output hold)
4
—
nS
Address and Attribute Outputs
B8
SDCLK to address (A[22:0]) valid
—
13.0
nS
B9
SDCLK to address (A[22:0]) invalid (output hold)
1.5
—
nS
Data Outputs
B11
SDCLK to data output (D[31:0]) valid
—
11
nS
B12
2
2
Data output is held valid for one CPU clock period after deassertion of BS[3:0]
SDCLK to data output (D[31:0]) invalid (output hold)
1
—
nS
B13
SDCLK to data output (D[31:0]) high impedance
—
6
nS
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