Sanyo DC-DAV821, Service Manual, Page: 49 / 81

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IC BLOCK DIAGRAM & DESCRIPTION
IC110,111,117 EM63615TS-8(SDRAM)
Symbol Type Description
CLK Input Clock: CLK is driven by the system clock. All SDRAM input signals are sampled on
the positive edge of CLK. CLK also increments the internal burst counter and controls
the output registers.
CKE Input Clock Enable: CKE activates(HIGH) and deactivates(LOW) the CLK signal.If CKE
goes low synchronously with clock(set-up and hold time same sa other inputs), the
internal clock is suspended from the next clock cycle and the state of output and
burst address is frozen as long as the CKE remains low. When both banks are in the
idle state, deactivating the clock controls the entry to the Power Down and Self Refresh
modes. CKE is synchronous except after the device enters Power Down and Self
Refresh modes, where CKE becomes asynchronous until exiting the same mode.
The input buffers, including CLK, are disabled during Power Down and Self Refresh
modes, providing low standby power.
A11 Input Bank Select: A11(BS) defines to which bank the BankActivate, Read, Write, or
BankPrecharge command is being applied.
AC-A10 Input Address Inputs: A0-A10 are sampled during the BankActivate command (row address
A0-A10 and Read/Write command (column address A0-A7 with A10 defining Auto
Precharge) to select one location out of the 256K available in the respective bank.
During a Precharge command, A10 is sampled to determine if both banks are to be
precharged (A10-HIGT). The address inputs also provide the op-code during a Mode
Register Set command.
CS# Input Chip Select: CS# enables (sampled LOW) and disables (sampled HIGH) the command
decoder. All commands are masked when CS# is sampled HIGH. CS# provides for
external bank selection on systems with multiple banks. It is considered part of
the command code.
RAS# Input Row Address Strobe: The RAS# signal defines the operation commands in conjunction
with the CAS# and WE# signals and is latched at the positive edges of CLK. When
RAS# and CS# are asserted "LOW" and CAS# is asserted "HIGH," either the
BankActivate command or the Precharge command is selected by the WE# signal.
When the WE# is asserted "HIGH," the BankActivate command is selected and the
bank designated by BS is turned on to the active state. When the WE# is asserted
"LOW," the Precharge command is selected and the bank designated by BS is
switched to the idle state after the precharge operation.
CAS# Input Column Address Strobe: The CAS# signal defines the operation commands in
conjunction with the RAS# and WE# signals and is latched at the positive edges of
CLK. When RAS# is held "HIGH" and CS# is asserted "LOW," the column access is
started by asserting CAS#"LOW." Then, the Read or Write command is selected by
asserting WE# "LOW" or "HIGH."
WE# Input Write Enable: The WE# signal defines the operation commands in conjunction with
the RAS# and CAS# signals and is latched at the positive edges of CLK. The WE#
input is used to select the BankActivate or Precharge command and Read or Write
command.
LDQM,
UDQM Input Data Input/Output Mask: LDQM and HDQM are byte specific, nonpersistent I/O buffer
controls. The I/O buffers are placed in a high-z state when DQM is sampled HIGH.
Input data is masked when DQM is sampled HIGH during a write cycle. Output data
is masked (two-clock latency) when DQM is sampled HIGH during a read cycle.
UDQM masks DQ15-DQ8, and LDQM masks DQ7-DQ0.
DQC-DQ15 Input /
Output
Data I/O: The DQ0-15 input and output data are synchronized with the positive edges
of CLK. The I/Os are byte-maskable during Reads and Writes.
NC - No Connect: These pins should be left unconnected.
V
DDQ
Supply DQ Power: Provide isolated power to DQs for improved noise immunity.(3.3V ± 0.3V)
V
SSQ
Supply DQ Ground: Provide isolsted ground to DQs for improved noise immunity.(0V)
V
DD
Supply Power Supply: +3.3V ± 0.3V
V
SS
Supply Ground