Harman Kardon AVR 255 Service Manual page 58

harman/kardon
PIN FUNCTION
SYMBOL
CLK, /CLK
CKE
/CS
/RAS, /CAS, /WE
A0-12
BA0,1
DQ0-7 (x8),
Input / Output
DQ0-15 (x16),
DQS (x8)
Input / Output
UDQS, LDQS (x16)
DM (x8)
UDM, LDM (x16)
Vdd, Vss Power Supply
VddQ, VssQ Power Supply
Vref
Revision 1.9
TYPE DESCRIPTION
Clock: CLK and /CLK are differential clock inputs. All address and control
input signals are sampled on the crossing of the positive edge of CLK and
Input
negative edge of /CLK. Output (read) data is referenced to the crossings of
CLK and /CLK (both directions of crossing).
Clock Enable: CKE controls internal clock. When CKE is low, internal clock
for the following cycle is ceased. CKE is also used to select auto / self refresh.
Input
After self refresh mode is started, CKE becomes asynchronous input. Self refresh
is maintained as long as CKE is low.
Input Chip Select: When /CS is high, any command means No Operation.
Input Combination of /RAS, /CAS, /WE defines basic commands.
A0-12 specify the Row / Column Address in conjunction with BA0,1. The
Row Address is specified by A0-12. The Column Address is specified by
A0-9(x8) and A0-8(x16). A10 is also used to indicate precharge
Input
option. When A10 is high at a read / write command, an auto precharge is
performed. When A10 is high at a precharge command, all banks are
precharged.
Bank Address: BA0,1 specifies one of four banks to which a command is
Input
applied. BA0,1 must be set with ACT, PRE, READ, WRITE commands.
Data Input/Output: Data bus
Data Strobe: Output with read data, input with write data. Edge-aligned
with read data, centered in write data. Used to capture write data.
For the x16, LDQS corresponds to the data on DQ0-DQ7; UDQS
correspond to the data on DQ8-DQ15
Input Data Mask: DM is an input mask signal for write data. Input data
is masked when DM is sampled HIGH along with that input data
during a WRITE access. DM is sampled on both edges of DQS.
Input
Although DM pins are input only, the DM loading matches the DQ
and DQS loading. For the x16, LDM corresponds to the data on DQ0-DQ7;
UDM corresponds to the data on DQ8-DQ15.
Power Supply for the memory array and peripheral circuitry.
VddQ and VssQ are supplied to the Output Buffers only.
Input SSTL_2 reference voltage.
256M Double Data Rate Synchronous DRAM
AVR 255/230 Service Manual
A3S56D30ETP
A3S56D40ETP
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