VIS
Pin Num- Symbol
ber
55
CLK
Type Description
Preliminary
VG4632321A
524,288x32x2-Bit
CMOS Synchronous Graphic RAM
Table 1 shows the details for pin number, symbol, type, and description.
Table 1. Pin Description of VG4632321A
Input
Clock:
CLK is driven by the system clock. All SGRAM input signals are sampled on
the positive edge of CLK. CLK also increments the internal burst counter and
control the output registers.
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 as 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 after exiting the
same mode. The input buffers, including CLK, are disabled during Power Down
and Self Refresh modes providing low standby power.
Input
Bank Select:
BS defines to which bank the BankActivate, Read, Write, or Bank-
Precharge command is being applied. BS is also used to program the 10th bit of
the Mode and Special Mode registers.
Input
Address Inputs:
A0-A10 are sampled during the BankActivate command (row
address A0-A10) and Read/Write command (column address A0-A7 with A8
defining Auto Precharge) to select one location out of the 512K available in the
respective bank. During a Precharge command, A8 is sampled to determine if both
banks are to be precharged (A8 = HIGH). The address inputs also provide the
op-code during a Mode Register Set or Special Mode Register Set command.
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.
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 precharge operation.
Input
Column Address Strobe:
The CAS signal defines the operation commands in
conjunction with the RAS and WE signals, and it 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”.
Input
Write Enable:
The WE signal defines the operation commands in conjunction with
the RAS and CAS signals, and it 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.
Input
Define Special Function:
The DSF signal defines the operation commands in
conjunction with the RAS and CAS and WE signals, and it is latched at the positive
edges of CLK. The DSF input is used to select the masked write disable/enable
command and block write command, and the Special Mode Register Set cycle.
54
CKE
29
BS
30-34,
45,47-51
A0-A10
28
CS
27
RAS
26
CAS
25
WE
53
DSF
Document:
Rev.1
Page 3
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