HD6417708SF60V Renesas Electronics America, HD6417708SF60V Datasheet - Page 271

• Manufacturer Part Number: HD6417708SF60V
• Description: IC SUPERH MPU ROMLESS 208LQFP
• Manufacturer: Renesas Electronics America
• Series: SuperH® SH7700r

Specifications of HD6417708SF60V

• Core Processor: SH-2
• Core Size: 32-Bit
• Speed: 60MHz
• Connectivity: EBI/EMI, SCI, SmartCard
• Peripherals: POR, WDT
• Number Of I /o: 8
• Program Memory Type: ROMless
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Oscillator Type: External
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 208-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Ram Size: -
• Program Memory Size: -
• Data Converters: -

Refresh Timing: The bus state controller includes a function for controlling DRAM refreshing.
Refreshing using a CAS-before-RAS cycle can be performed by clearing the RMODE bit to 0 and
setting the RFSH bit to 1 in MCR for area 3 DRAM, or by clearing the RMODE bit to 0 and
setting the RFSH bit to 1 in DCR for area 2 DRAM. It also supports self-refresh mode.
When CAS-before-RAS refresh cycles are executed, refreshing is performed at intervals
determined by the input clock selected by bits CKS2–CKS0 in RTCSR, and the value set in
RTCOR. The value of bits CKS2–CKS0 in RTCOR should be set so as to satisfy the stipulation
for the DRAM refresh interval. First make the settings for RTCOR, RTCNT, and the RMODE and
RFSH bits in MCR, then make the CKS2–CKS0 setting. When the clock is selected by CKS2 to
CKS0, RTCNT starts counting up from the value at that time. The RTCNT value is constantly
compared with the RTCOR value, and if the two values are the same, a refresh request is
generated and the IRQOUT pin goes low. If the SH7708 Series’ external bus can be used, CAS-
before-RAS refreshing is performed, and if there is no other interrupt request the IRQOUT pin
goes high. At the same time, RTCNT is cleared to zero and the count-up is restarted. Figure 10.20
shows the operation of CAS-before-RAS refreshing.
H'00000000
RTCSR.CKS(2–0)
RTCNT
CMF
External bus
RTCOR value
Figure 10.20 CAS-Before-RAS Refresh Operation
CMF flag cleared by start of
refresh cycle
= 000
000
CAS-before-RAS refresh cycle
RTCNT cleared to 0 when
RTCNT = RTCOR
Time
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