HD6417020SX20IV Renesas Electronics America, HD6417020SX20IV Datasheet - Page 169

• Manufacturer Part Number: HD6417020SX20IV
• Description: SH 1 CORE 32B MPU, 20MHZ/5V, 100
• Manufacturer: Renesas Electronics America
• Series: SuperH® SH7020r

Specifications of HD6417020SX20IV

• Core Processor: SH-1
• Core Size: 32-Bit
• Speed: 20MHz
• Connectivity: EBI/EMI, SCI
• Peripherals: DMA, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Type: ROMless
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-TQFP, 100-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -

refresh will not be performed until the RTCNT again matches the RTCOR value, the initial refresh
interval will be rather long. It is thus advisable to set the RTCOR cycle prior to setting the CKS2–
CKS0 bits and start it incrementing. When CBR refresh control is being performed after its use as
an 8-bit interval timer, the RTCNT count value may be in excess of the refresh cycle. For this
reason, clear the RTCNT by writing H'00 before starting refresh control to assure a correct refresh
interval.
When the RW1 bit of WCR1 is set to 1 and the read cycle is set to long pitch, the number of wait
states selected by the RLW1 and RLW0 bits of the RCR will be inserted into the CBR refresh
cycle, regardless of the status of the WAIT signal. Figure 8.29 shows the RTCNT operation and
figure 8.30 shows the timing of the CBR refresh. For details on timing, see section 20.3.3, Bus
Timing.
Self-Refresh Mode: Some DRAMs have a self-refresh mode (parity back-up mode). This is a
type of a standby mode in which the refresh timing and refresh addresses are generated inside the
DRAM chip. When the RFSHE and RMODE bits of the RCR are both set to 1, the DRAM will
RTCOR
value
H'00
RAS
CAS
RTCNT
value
CK
Clock
selected with
CKS2–CKS0
Figure 8.30 Output Timing for CAS-Before-RAS Refresh Signal
Figure 8.29 Refresh Timer Counter (RTCNT) Operation
with RTCOR
Compare
match
CBR
T
Rp
CBR: CAS-before-RAS refresh
with RTCOR
Compare
T
match
CBR
Rr
with RTCOR
T
Compare
Rc
match
CBR
with RTCOR
Compare
match
CBR
RENESAS 149
Time