HD6417708SF60 Renesas Electronics America, HD6417708SF60 Datasheet - Page 287

• Manufacturer Part Number: HD6417708SF60
• Description: IC SUPERH MPU ROMLESS 144LQFP
• Manufacturer: Renesas Electronics America
• Series: SuperH® SH7700r

Specifications of HD6417708SF60

• 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: 144-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Ram Size: -
• Program Memory Size: -
• Data Converters: -

2. Self-Refreshing
Self-refresh mode is a kind of standby mode in which the refresh timing and refresh addresses are
generated within the synchronous DRAM. Self-refreshing is activated by setting both the RMODE
bit and the RFSH bit to 1. The self-refresh state is maintained while the CKE signal is low.
Synchronous DRAM cannot be accessed while in the self-refresh state. Self-refresh mode is
cleared by clearing the RMODE bit to 0. After self-refresh mode has been cleared, command
issuance is disabled for the number of cycles specified by the TPC bits in MCR. Self-refresh
timing is shown in figure 10.31. Settings must be made so that self-refresh clearing and data
retention are performed correctly, and auto-refreshing is performed at the correct intervals. When
self-refreshing is activated from the state in which auto-refreshing is set, or when exiting standby
mode other than through a power-on reset, auto-refreshing is restarted if RFSH is set to 1 and
RMODE is cleared to 0 when self-refresh mode is cleared. If the transition from clearing of self-
refresh mode to the start of auto-refreshing takes time, this time should be taken into consideration
when setting the initial value of RTCNT. Making the RTCNT value 1 less than the RTCOR value
will enable refreshing to be started immediately.
After self-refreshing has been set, the self-refresh state continues even if the chip standby state is
entered using the SH7708 Series’s standby function, and is maintained even after recovery from
standby mode other than through a power-on reset. For a power-on reset, the bus state controller’s
registers are initialized, thereby clearing the self-refresh state.
CKIO
CKE
CSn
RAS
CASxx
RD/WR
Figure 10.30 Synchronous DRAM Auto-Refresh Timing
TRr
TRrw
TRrw
(Tpc)
(Tpc)
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