DF2338VFC25V Renesas Electronics America, DF2338VFC25V Datasheet - Page 211

• Manufacturer Part Number: DF2338VFC25V
• Description: IC H8S/2300 MCU FLASH 144QFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8S/2300r

Specifications of DF2338VFC25V

• Core Processor: H8S/2000
• Core Size: 16-Bit
• Speed: 25MHz
• Connectivity: SCI, SmartCard
• Peripherals: DMA, POR, PWM, WDT
• Number Of I /o: 106
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 12x10b; D/A 4x8b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 144-QFP
• For Use With: EDK2329 - DEV EVALUATION KIT H8S/2329
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

6.5.11
The chip is provided with a DRAM refresh control function. Either of two refreshing methods can
be selected: CAS-before-RAS (CBR) refreshing, or self-refreshing.
CAS-before-RAS (CBR) Refreshing: To select CBR refreshing, set the RFSHE bit in DRAMCR
to 1, and clear the RMODE bit to 0.
With CBR refreshing, RTCNT counts up using the input clock selected by bits CKS2 to CKS0 in
DRAMCR, and when the count matches the value set in RTCOR (compare match), refresh control
is performed. At the same time, RTCNT is reset and starts counting again from H'00. Refreshing is
thus repeated at fixed intervals determined by RTCOR and bits CKS2 to CKS0. Set a value in bits
CKS2 to CKS0 in RTCOR that will meet the refreshing interval specification for the DRAM used.
When bits CKS2 to CKS0 are set, RTCNT starts counting up. RTCNT and RTCOR settings
should therefore be completed before setting bits CKS2 to CKS0.
Do not clear the CMF flag when refresh control is performed (RFSHE = 1).
RTCNT operation is shown in figure 6.23, compare match timing in figure 6.24, and CBR refresh
timing in figure 6.25.
Another normal space access can be performed during the CBR refresh interval.
RTCOR
H'00
Refresh request
Refresh Control
RTCNT
Figure 6.23 RTCNT Operation
Rev.4.00 Sep. 07, 2007 Page 179 of 1210
REJ09B0245-0400