7
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T1845/55/65/75/85/95/105/115/125 2.5V TeraSync™ 18-BIT/9-BIT FIFO
2Kx18/4Kx9, 4Kx18/
8Kx9, 8Kx18/16Kx9, 16Kx18/32Kx9, 32Kx18/64Kx9, 64Kx18/128Kx9, 128Kx18/256Kx9, 256Kx18/512Kx9, 512Kx18/1Mx9
FEBRUARY 10, 2009
PIN DESCRIPTION
Symbol Name I/O TYPE Description
ASYR
(1)
Asynchronous LVTTL A HIGH on this input during Master Reset will select Synchronous read operation for the output port. A LOW
Read Port INPUT will select Asynchronous operation. If Asynchronous is selected the FIFO must operate in IDT Standard mode.
ASYW
(1)
Asynchronous LVTTL A HIGH on this input during Master Reset will select Synchronous write operation for the input port. A LOW
Write Port INPUT will select Asynchronous operation.
BE
(1)
Big-Endian/ LVTTL During Master Reset, a LOW on BE will select Big-Endian operation. A HIGH on BE during Master Reset
Little-Endian INPUT will select Little-Endian format.
D0–D17 Data Inputs HSTL-LVTTL Data inputs for an 18- or 9-bit bus. When in 18- or 9-bit mode, the unused input pins should be tied to GND.
INPUT
EF/OR Empty Flag/ HSTL-LVTTL In the IDT Standard mode, the EF function is selected. EF indicates whether or not the FIFO memory is empty.
Output Ready OUTPUT In FWFT mode, the OR function is selected. OR indicates whether or not there is valid data available at the
outputs.
ERCLK RCLK Echo HSTL-LVTTL Read clock Echo output, only available when the Read is setup for Synchronous mode.
OUTPUT
EREN Read Enable Echo HSTL-LVTTL Read Enable Echo output, only available when the Read is setup for Synchronous mode.
OUTPUT
FF/IR Full Flag/ HSTL-LVTTL In the IDT Standard mode, the FF function is selected. FF indicates whether or not the FIFO memory is
Input Ready OUTPUT full. In the FWFT mode, the IR function is selected. IR indicates whether or not there is space available for
writing to the FIFO memory.
FSEL0
(1)
Flag Select Bit 0 LVTTL During Master Reset, this input along with FSEL1 and the LD pin, will select the default offset values for the
INPUT programmable flags PAE and PAF. There are up to eight possible settings available.
FSEL1
(1)
Flag Select Bit 1 LVTTL During Master Reset, this input along with FSEL0 and the LD pin will select the default offset values for the
INPUT programmable flags PAE and PAF. There are up to eight possible settings available.
FWFT/ First Word Fall HSTL-LVTTL During Master Reset, selects First Word Fall Through or IDT Standard mode. After Master Reset, this pin
SI Through/Serial In INPUT functions as a serial input for loading offset registers. If Asynchronous operation of the read port has been
selected then the FIFO must be setup in IDT Standard mode.
HF Half-Full Flag HSTL-LVTTL HF indicates whether the FIFO memory is more or less than half-full.
OUTPUT
IP
(1)
Interspersed Parity LVTTL During Master Reset, a LOW on IP will select Non-Interspersed Parity mode. A HIGH will select Interspersed
INPUT Parity mode.
IW
(1)
Input Width LVTTL This pin, along with OW, selects the bus width of the write port. See Table 1 for bus size configuration.
INPUT
LD Load HSTL-LVTTL This is a dual purpose pin. During Master Reset, the state of the LD input along with FSEL0 and FSEL1,
INPUT determines one of eight default offset values for the PAE and PAF flags, along with the method by which these
offset registers can be programmed, parallel or serial (see Table 2). After Master Reset, this pin enables writing
to and reading from the offset registers. THIS PIN MUST BE HIGH AFTER MASTER RESET TO WRITE
OR READ DATA TO/FROM THE FIFO MEMORY.
MARK Mark for Retransmit HSTL-LVTTL When this pin is asserted the current location of the read pointer will be marked. Any subsequent Retransmit
INPUT operation will reset the read pointer to this position.
MRS Master Reset HSTL-LVTTL MRS initializes the read and write pointers to zero and sets the output register to all zeroes. During Master
INPUT Reset, the FIFO is configured for either FWFT or IDT Standard mode, Bus-Matching configurations,
Synchronous/Asynchronous operation of the read or write port, one of eight programmable flag default settings,
serial or parallel programming of the offset settings, Big-Endian/Little-Endian format, zero latency timing mode,
interspersed parity, and synchronous versus asynchronous programmable flag timing modes.
OE Output Enable HSTL-LVTTL OE provides Asynchronous three-state control of the data outputs, Qn. During a Master or Partial Reset the
INPUT OE input is the only input that provide High-Impedance control of the data outputs.
OW
(1)
Output Width LVTTL This pin, along with IW, selects the bus width of the read port. See Table 1 for bus size configuration.
INPUT
PAE Programmable HSTL-LVTTL PAE goes LOW if the number of words in the FIFO memory is less than offset n, which is stored in the Empty
Almost-Empty Flag OUTPUT Offset register. PAE goes HIGH if the number of words in the FIFO memory is greater than or equal to offset n.
PAF Programmable HSTL-LVTTL PAF goes HIGH if the number of free locations in the FIFO memory is more than offset m, which is stored in
Almost-Full Flag OUTPUT the Full Offset register. PAF goes LOW if the number of free locations in the FIFO memory is less than or equal
to m.
PFM
(1)
Programmable LVTTL During Master Reset, a LOW on PFM will select Asynchronous Programmable flag timing mode. A HIGH on
Flag Mode INPUT PFM will select Synchronous Programmable flag timing mode.
