DF2398TE20 Renesas Electronics America, DF2398TE20 Datasheet - Page 177

• Manufacturer Part Number: DF2398TE20
• Description: IC H8S MCU FLASH 256K 120TQFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8S/2300r

Specifications of DF2398TE20

• Core Processor: H8S/2000
• Core Size: 16-Bit
• Speed: 20MHz
• Connectivity: SCI, SmartCard
• Peripherals: DMA, POR, PWM, WDT
• Number Of I /o: 87
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 120-TQFP, 120-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Other names: HD64F2398TE20; HD64F2398TE20

6.5.11
The H8S/2357 Group 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 RTCOR and bits CKS2 to CKS0 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 being performed (RFSHE = 1).
RTCNT operation is shown in figure 6-23, compare match timing in figure 6-24, and CBR refresh timings in figure 6-25.
Refresh Control
Refresh request
Refresh request signal
and CMF bit setting signal
RTCOR
H'00
RTCNT
RTCOR
ø
RTCNT
Figure 6-24 Compare Match Timing
Figure 6-23 RTCNT Operation
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Rev.6.00 Oct.28.2004 page 147 of 1016
H'00
REJ09B0138-0600H