SH7020 Datasheet, PDF (177/509 Pages) Renesas Technology Corp – SuperH™ RISC engine

BREQ
BACK
Refresh damand
Refresh execution
Figure 8.36 BACK Operation by Refresh Demand (1)
If BACK has not gone low after waiting for the maximum
number of states* before the SuperH releases the bus, return
BREQ to the high level.
BREQ
BACK
Refresh request
BACK does not go low.
Note: * For details see section 8.11.3, Maximum Number of States from BREQ Input to Bus Release.
Figure 8.37 BACK Operation in Response to Refresh Request (2)
8.10.2 BACK Operation
1. BACK Operation
When an internal refresh is requested during an attempt to assert the BACK signal and BACK
is not asserted but remains high, a momentary narrow pulse-shaped spike may be output, as
shown below.
BREQ
BACK
Refresh demand
pulse width of the spike is approx. 2 to 5 ns.
RENESAS 159