TC59LM914/06AMG-37,-45,-50
2004-03-16 51/58
Rev 0.91
COMMAND FUNCTIONS and OPERATIONS
TC59LM914/06AMG 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 Upper Addresses to the idle bank puts the bank
designated by Bank Addr ess in a re ad mod e. Wh en th e LAL command with Lower Addresses i s i ssu ed at the ne xt
clock of the RDA command, the data is read out sequentially synchronizing with the both edges of DQS/DQS
output signal (Burst Read Oper ation). The initial valid read data appe ars 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. DQS is differen tial data strobe signal su pported TC59LM906AMG.
Write Operation (1st command + 2nd command = WRA + LAL)
Issuing the WRA command with Bank Addresses and Upper Addresses to the idle bank puts the bank
designated 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/DQS input signal (Bu rst Write Operation). Th e data and DQS/DQS inputs have to be asserted in keeping
with clock input after CAS latency-1 from the issuing of the LAL command. The DQS/DQS h as to be provided
for a burst length. Th e CAS latency and th e burst type must be set in the Mo de Register beforehand. Th e 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. DQS is differential data strobe signal supported
TC59LM906AMG.
Auto-Refresh Operation (1st command + 2nd command = WRA + REF)
TC59LM914/06AMG are r e quired to refresh like a standard SDRAM. The Auto-Refresh operation is beg un 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. 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 h as to be issued within once for every 7.8 µs by the maxi mum. In case of burst refresh or
random distributed refr esh, the average interv al of eight consecutiv e Auto-Refresh command h as to be more than
400 ns always. In other words, th e number of Auto-Refresh cycles that be perfor med within 3.2 µs (8 × 400 ns) is
to 8 times in the maximu m.
Self-Refresh Operation (1st command + 2nd command = WRA + REF with = “L”)
In case of Self-Refresh operation, refresh operation can be performed automatically by u sing an internal timer.
When all banks are in the idle state and all outputs are in Hi-Z states, the TC59LM914/06AMG become
Self-Refresh mode by issu ing 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 th e idle state an d DQ outputs are in Hi-Z states, th e TC59LM914/06 AMG become Powe r
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 h as to be brought to “High” and the DESL command has to be issued for two clock cycle
after PD goes high. The Power Down exit function is asynchronous operation.
PD
PD