DF2357F20 Renesas Electronics America, DF2357F20 Datasheet - Page 175

• Manufacturer Part Number: DF2357F20
• Description: IC H8S MCU FLASH 5V 128K 128QFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8S/2300r

Specifications of DF2357F20

• 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: 128KB (128K 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: 128-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

RAS Down Mode and RAS Up Mode: Even when burst operation is selected, it may happen that access to DRAM space
is not continuous, but is interrupted by access to another space. In this case, if the RAS signal is held low during the
access to the other space, burst operation can be resumed when the same row address in DRAM space is accessed again.
RAS down mode
To select RAS down mode, set the RCDM bit in MCR to 1. If access to DRAM space is interrupted and another space
is accessed, the RAS signal is held low during the access to the other space, and burst access is performed if the row
address of the next DRAM space access is the same as the row address of the previous DRAM space access. Figure 6-
21 shows an example of the timing in RAS down mode.
Note, however, that the RAS signal will go high if a refresh operation interrupts RAS down mode.
CAS, LCAS
CSn, (RAS)
D
Note: n = 2 to 5
A
15
23
to D
to A
ø
0
0
Figure 6-21 Example of Operation Timing in RAS Down Mode
T
p
DRAM access
T
r
T
c1
T
c2
External space
T
1
access
T
2
Rev.6.00 Oct.28.2004 page 145 of 1016
DRAM access
T
c1
T
c2
REJ09B0138-0600H