mcf54455 Freescale Semiconductor, Inc, mcf54455 Datasheet - Page 23

• Manufacturer Part Number: mcf54455
• Description: 32-bit Microprocessor With Usb On-the-go, Ethernet, Pci, Ddr2/ddr Controller And Encryption
• Manufacturer: Freescale Semiconductor, Inc

5.7
A multi-function external bus interface called FlexBus is provided with basic functionality to interface to slave-only devices up
to a maximum bus frequency of 66MHz. It can be directly connected to asynchronous or synchronous devices such as external
boot ROMs, flash memories, gate-array logic, or other simple target (slave) devices with little or no additional circuitry. For
asynchronous devices, a simple chip-select based interface can be used.
All processor bus timings are synchronous; input setup/hold and output delay are given in respect to the rising edge of a
reference clock, FB_CLK. The FB_CLK frequency may be the same as the internal system bus frequency or an integer divider
of that frequency.
The following timing numbers indicate when data is latched or driven onto the external bus, relative to the Flexbus output clock
(FB_CLK). All other timing relationships can be derived from these values.
Freescale Semiconductor
1
2
Configuration Overrides*:
FlexBus Timing Specifications
Num
FB1
FB2
FB3
FB4
FB5
Specification is valid for all FB_AD[31:0], FB_BS[3:0], FB_CS[3:0], FB_OE, FB_R/W, FB_TBST,
FB_TSIZ[1:0], and FB_TS.
Specification is valid for all FB_AD[31:0] and FB_TA.
(BOOTMOD[1:0],
Override pins])
Frequency of Operation
Clock Period
Output Valid
Output Hold
Input Setup
Input Hold
RSTOUT
RESET
CLKIN
Figure 8. RESET and Configuration Override Timing
MCF5445x ColdFire
Table 12. FlexBus AC Timing Specifications
R1
Characteristic
R3
®
Microprocessor Data Sheet, Rev. 0
R2
R4
Min
1.0
3.0
25
15
—
0
R5
66.66
Max
7.0
40
—
—
—
R6
MHz
Unit
Electrical Characteristics
ns
ns
ns
ns
ns
R4
R7
Notes
1
2
1
2
R8
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