TC59LM913/05AMB-50,-55,-60
2003-08-04 45/50
COMMAND FUNCTIONS and OPERATIONS
TC59LM913/05AMB are introduced the two consecutive command input method. Therefore, except for Power
Down mode, each operation mode decided by the combination of the first command and the second command from
stand-by states of the bank to be accessed.
Read Operation (1st command + 2nd command = RDA + LAL)
Issuing the RDA command with Bank Addresses and U pper Addresses to the idle bank puts the bank designate d
by Bank Address in a re ad mode. When the LAL command with Lower Addresses is issued at the next clock of the
RDA command, the data is read out sequentially synchronizing with the both edges of DQS output signal (Burst
Read Operation). The initial valid read data appears after CAS latency from the issuing of the LAL command.
The valid data is outputted for a burst length. The CAS latency, the burst length of read data and the burst type
must be set in the Mode Register beforehand. The read operated bank goes back automatically to the idle state
after lRC.
Write Operation (1st command + 2nd command = WRA + LAL)
Issuing the WRA command with Bank Addr esses an d U pper Addresses to the i dle b an k puts the bank desig nated
by Bank Address in a write mode. When the LAL command with Lower Addresses is issued at the next clock of the
WRA command, the input data is latched sequentially synchronizing with the both edges of DQS input signal
(Burst Write Operation). The data and DQS inputs have to be asserted in keeping with clock input after CAS
latency-1 from the issuing of the LAL command. The DQS has to be provided for a burst length. The CAS latency
and the burst type must be set in the Mode Register beforehand. The write operated bank goes back automatically
to the idle state after lRC. Write Burst Length is controlled by VW0 and VW1 inputs with LAL command. See VW
truth table.
Auto-Refresh Operation (1st command + 2nd command = WRA + REF)
TC59LM913/05AMB are required to refresh like a standard SDRAM. The Auto-Refresh operation is begun with
the REF command following to the WRA command. The Auto-Refresh mode can be effective only when all banks are
in the idle state and all outputs are in Hi-Z states. In a point to notice, the write mode started with the WRA
command is canceled by the REF command having gone into the next clock of the WRA command instead of the
LAL command. The minimum period between the Auto-Refresh command and the next command is specified by
lREFC. However, about a synthetic average interval of Auto-Refresh command, it must be careful. In case of equally
distributed refresh, Auto-Refresh command has to be issued within once for every 7.8 µs by the maximum. In case
of burst refresh or random distributed refresh, the average interval of eight consecutive Auto-Refresh commands
has to be more than 400 ns always. In other words, th e number of Auto-Refresh cycles that can be performed within
3.2 µs (8 × 400 ns) is to 8 times in the maximum.
Self-Refresh Operation (1st command + 2nd command = WRA + REF with = “L”)
In case of Self-Refresh operation, refresh operation can be performed automatically by using an internal timer.
When all banks are in the idle state and all outputs are in Hi-Z states, the TC59LM913/05AMB become
Self-Refresh mode by issuing the Self-Refresh command. PD has to be brought to “Low” within tFPDL from the
REF command following to the WRA command for a Self-Refresh mode entry. In order to satisfy the refresh period,
the Self-Refresh entry command should be asserted within 7.8 µs after the latest Auto-Refresh command. Once the
device enters Self-Refresh mode, the DESL command must be continued for lREFC period. In addition, it is
desirable that clock input is kept in lCKD period. The device is in Self-Refresh mode as long as PD held “Low”.
During Self-Refresh mode, all input and output buffers are disabled except for PD , therefore the power dissipation
lowers. Regarding a Self-Refresh mode exit, PD has to be changed over from “Low” to “High” along with the DESL
command, and the DESL command has to be continuously issued in the number of clocks specified by lREFC. The
Self-Refresh exit function is asynchronous operation. It is required that one Auto-Refresh command is issued to
avoid the violation of the refresh period just after lREFC from Self-Refresh exit.
Power Down Mode ( = “L”)
When all banks are in the idle state and DQ outputs are in Hi-Z states, the TC59LM913/05AMB become Power
Down Mode by asserting PD is “Low”. When the device enters the Power Down Mode, all input and output buffers
are disabled after specified time except for PD . Therefore, the power dissipation lowers. To exit the Power Down
Mode, PD has to be brought to “High” and the DESL command has to be issued for two clocks cycle after PD
goes high. The Power Down exit function is asynchronous operation.
PD
PD