PSB21473FV13XT Infineon Technologies, PSB21473FV13XT Datasheet - Page 171

• Manufacturer Part Number: PSB21473FV13XT
• Manufacturer: Infineon Technologies

Specifications of PSB21473FV13XT

• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (min): 3.135V
• Operating Supply Voltage (max): 3.6V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 144
• Lead Free Status / RoHS Status: Compliant

INCA-D
PSB 21473
The External Bus Interface
Figure 11-8 Memory Tri-State Time
The output of the next address on the external bus can be delayed for a memory or
peripheral, which needs more time to switch off its bus drivers, by introducing a wait state
after the previous bus cycle (see figure above). During this memory tri-state time wait
state, the CPU is not idle, so CPU operations will only be slowed down if a subsequent
external instruction or data fetch operation is required during the next instruction cycle.
The memory tri-state time waitstate requires one CPU clock (28 ns at f
= 36 MHz)
CPU
and is controlled via the MTTCx bits of the BUSCON registers. A waitstate will be
inserted, if bit MTTCx is ‘0’ (default after reset).
Note: External bus cycles in multiplexed bus modes implicitly add one tri-state time
waitstate in addition to the programmable MTTC waitstate.
Read/Write Signal Delay
The INCA-D allows the user to adjust the timing of the read and write commands to
account for timing requirements of external peripherals. The read/write delay controls the
time between the falling edge of ALE and the falling edge of the command. Without read/
write delay the falling edges of ALE and command(s) are coincident (except for
propagation delays). With the delay enabled, the command(s) become active half a CPU
clock after the falling edge of ALE.
The read/write delay does not extend the memory cycle time, and does not slow down
the controller in general. In multiplexed bus modes, however, the data drivers of an
external device may conflict with the INCA-D’s address, when the early RD signal is
used. Therefore multiplexed bus cycles should always be programmed with read/write
delay.
Data Sheet
171
2003-03-31