19
IDT72V51433/72V51443/72V51453 3.3V, MULTI-QUEUE FLOW-CONTROL DEVICES
(16 QUEUES) 18 BIT WIDE CONFIGURATION 589,824, 1,179,648 and 2,359,296 bits
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
NULL QUEUE OPERATION (OF THE READ PORT)
Pipelining of data to the output port enables the device to provide 100% bus
utilization in standard mode. Data can be read out of the multi-queue flow-control
device on every RCLK cycle regardless of queue switches or other opera-
tions. The device architecture is such that the pipeline is constantly filled with
the next words in a selected queue to be read out, again providing 100% bus
utilization. This type of architecture does assume that the user is constantly
switching queues such that during a queue switch, the last data word required
from the previous queue will fall through the pipeline to the output.
Note, that if reads cease at the empty boundary of a queue, then the last word
will automatically flow through the pipeline to the output.
The Null-Q is selected via read port address space RDADD[4]. The
RDADD[7:0] bus should be addressed with xxx1xxxx, this address is the
Null-Q. A null queue can be selected when no further reads are required from
a previously selected queue. Changing to a null queue will continue to
propagate data in the pipeline to the previous queue’s output. The Null-Q can
remain selected until a data becomes available in another queue for reading.
The Null-Q can be utilized in either standard or packet mode.
Note: If the user switches the read port to the null queue, this queue is seen
as and treated as an empty queue, therefore after switching to the null queue
the last word from the previous queue will remain in the output register and the
OV flag will go HIGH, indicating data is not valid.
The Null queue operation only has significance to the read port of the multi-
queue, it is a means to force data through the pipeline to the output. Null-Q
selection and operation has no meaning on the write port of the device. Also,
refer to Figure 16, Read Operation and Null Queue Select for diagram.
BUS MATCHING OPERATION
Bus Matching operation between the input port and output port is available.
During a master reset of the multi-queue the state of the two setup pins, IW (Input
Width) and OW (Output Width) determine the input and output port bus widths
as per the selections shown in Table 3, “Bus Matching Set-up”. 9 bit bytes or
18 bit words can be written into and read from the queues. When writing to or
reading from the multi-queue in a bus matching mode, the device orders data
in a “Little Endian” format. See Figure 3, Bus Matching Byte Arrangement for
details.
The Full flag and Almost Full flag operation is always based on writes and
reads of data widths determined by the write port width. For example, if the input
port is x18 and the output port is x9, then two data reads from a full queue will
be required to cause the full flag to go HIGH (queue not full). Conversely, the
Output Valid flag and Almost Empty flag operations are always based on writes
and reads of data widths determined by the read port. For example, if the input
port is x9 and the output port is x18, two write operations will be required to cause
the output valid flag of an empty queue to go LOW, output valid (queue is not
empty).
Note, that the input port serves all queues within a device, as does the output
port, therefore the input bus width to all queues is equal (determined by the input
port size) and the output bus width from all queues is equal (determined by the
output port size).
FULL FLAG OPERATION
The multi-queue flow-control device provides a single Full Flag output, FF.
The FF flag output provides a full status of the queue currently selected on the
write port for write operations. Internally the multi-queue flow-control device
monitors and maintains a status of the full condition of all queues within it, however
only the queue that is selected for write operations has its full status output to the
FF flag. This dedicated flag is often referred to as the “active queue full flag”.
When queue switches are being made on the write port, the FF flag output
will switch to the new queue and provide the user with the new queue status,
on the cycle after a new queue selection is made. The user then has a full status
for the new queue one cycle ahead of the WCLK rising edge that data can be
written into the new queue. That is, a new queue can be selected on the write
port via the WRADD bus, WADEN enable and a rising edge of WCLK. On the
next rising edge of WCLK, the FF flag output will show the full status of the newly
selected queue. On the second rising edge of WCLK following the queue
selection, data can be written into the newly selected queue provided that data
and enable setup & hold times are met.
Note, the FF flag will provide status of a newly selected queue one WCLK
cycle after queue selection, which is one cycle before data can be written to that
queue. This prevents the user from writing data to a queue that is full, (assuming
that a queue switch has been made to a queue that is actually full).
The FF flag is synchronous to the WCLK and all transitions of the FF flag occur
based on a rising edge of WCLK. Internally the multi-queue device monitors and
keeps a record of the full status for all queues. It is possible that the status of a
FF flag maybe changing internally even though that flag is not the active queue
flag (selected on the write port). A queue selected on the read port may
experience a change of its internal full flag status based on read operations.
See Figure 9, Write Queue Select, Write Operation and Full Flag Operation
and Figure 11, Full Flag Timing in Expansion Mode for timing information.
EXPANSION MODE - FULL FLAG OPERATION
When multi-queue devices are connected in Expansion mode the FF flags
of all devices should be connected together, such that a system controller
monitoring and managing the multi-queue devices write port only looks at a
single FF flag (as opposed to a discrete FF flag for each device). This FF flag
is only pertinent to the queue being selected for write operations at that time.
Remember, that when in expansion mode only one multi-queue device can be
written to at any moment in time, thus the FF flag provides status of the active
queue on the write port.
This connection of flag outputs to create a single flag requires that the FF flag
output have a High-Impedance capability, such that when a queue selection is
made only a single device drives the FF flag bus and all other FF flag outputs
connected to the FF flag bus are placed into High-Impedance. The user does
not have to select this High-Impedance state, a given multi-queue flow-control
device will automatically place its FF flag output into High-Impedance when none
of its queues are selected for write operations.
When queues within a single device are selected for write operations, the FF
flag output of that device will maintain control of the FF flag bus. Its FF flag will
simply update between queue switches to show the respective queue full status.
The multi-queue device places its FF flag output into High-Impedance based
on the 3 bit ID code found in the 3 most significant bits of the write queue address
bus, WRADD. If the 3 most significant bits of WRADD match the 3 bit ID code setup
on the static inputs, ID0, ID1 and ID2 then the FF flag output of the respective
device will be in a Low-Impedance state. If they do not match, then the FF flag
output of the respective device will be in a High-Impedance state. See Figure
11, Full Flag Timing in Expansion Mode for details of flag operation, including
when more than one device is connected in expansion.
IW OW Write Port Read Port
0 0 x18 x18
0 1 x18 x9
1 0 x9 x18
1 1 x9 x9
TABLE 3
BUS-MATCHING SET-UP
20
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72V51433/72V51443/72V51453 3.3V, MULTI-QUEUE FLOW-CONTROL DEVICES
(16 QUEUES) 18 BIT WIDE CONFIGURATION 589,824, 1,179,648 and 2,359,296 bits
OUTPUT VALID FLAG OPERATION
The multi-queue flow-control device provides a single Output Valid flag
output, OV. The OV provides an empty status or data output valid status for the
data word currently available on the output register of the read port. The rising
edge of an RCLK cycle that places new data onto the output register of the read
port, also updates the OV flag to show whether or not that new data word is
actually valid. Internally the multi-queue flow-control device monitors and
maintains a status of the empty condition of all queues within it, however only
the queue that is selected for read operations has its output valid (empty) status
output to the OV flag, giving a valid status for the word being read at that time.
The nature of the first word fall through operation means that when the last
data word is read from a selected queue, the OV flag will go HIGH on the next
enabled read, that is, on the next rising edge of RCLK while REN is LOW.
When queue switches are being made on the read port, the OV flag will switch
to show status of the new queue in line with the data output from the new queue.
When a queue selection is made the first data from that queue will appear on
the Qout data outputs 2 RCLK cycles later, the OV will change state to indicate
validity of the data from the newly selected queue on this 2
nd
RCLK cycle also.
The previous cycles will continue to output data from the previous queue and
the OV flag will indicate the status of those outputs. Again, the OV flag always
indicates status for the data currently present on the output register.
The OV flag is synchronous to the RCLK and all transitions of the OV flag occur
based on a rising edge of RCLK. Internally the multi-queue device monitors and
keeps a record of the output valid (empty) status for all queues. It is possible that
the status of an OV flag may be changing internally even though that respective
flag is not the active queue flag (selected on the read port). A queue selected
on the write port may experience a change of its internal OV flag status based
on write operations, that is, data may be written into that queue causing it to
become “not empty”.
See Figure 12, Read Queue Select, Read Operation and Figure 13, Output
Valid Flag Timing for details of the timing.
EXPANSION MODE – OUTPUT VALID FLAG OPERATION
When multi-queue devices are connected in Expansion mode, the OV flags
of all devices should be connected together, such that a system controller
monitoring and managing the multi-queue devices read port only looks at a
single OV flag (as opposed to a discrete OV flag for each device). This OV flag
is only pertinent to the queue being selected for read operations at that time.
Remember, that when in expansion mode only one multi-queue device can be
read from at any moment in time, thus the OV flag provides status of the active
queue on the read port.
This connection of flag outputs to create a single flag requires that the OV flag
output have a High-Impedance capability, such that when a queue selection is
made only a single device drives the OV flag bus and all other OV flag outputs
connected to the OV flag bus are placed into High-Impedance. The user does
not have to select this High-Impedance state, a given multi-queue flow-control
device will automatically place its OV flag output into High-Impedance when none
of its queues are selected for read operations.
When queues within a single device are selected for read operations, the OV
flag output of that device will maintain control of the OV flag bus. Its OV flag will
simply update between queue switches to show the respective queue output
valid status.
The multi-queue device places its OV flag output into High-Impedance based
on the 3 bit ID code found in the 3 most significant bits of the read queue address
bus, RDADD. If the 3 most significant bits of RDADD match the 3 bit ID code setup
on the static inputs, ID0, ID1 and ID2 then the OV flag output of the respective
device will be in a Low-Impedance state. If they do not match, then the OV flag
output of the respective device will be in a High-Impedance state. See Figure
13, Output Valid Flag Timing for details of flag operation, including when more
than one device is connected in expansion.
ALMOST FULL FLAG
As previously mentioned the multi-queue flow-control device provides a
single Programmable Almost Full flag output, PAF. The PAF flag output provides
a status of the almost full condition for the active queue currently selected on the
write port for write operations. Internally the multi-queue flow-control device
monitors and maintains a status of the almost full condition of all queues within
it, however only the queue that is selected for write operations has its full status
output to the PAF flag. This dedicated flag is often referred to as the “active queue
almost full flag”. The position of the PAF flag boundary within a queue can be
at any point within that queues depth. This location can be user programmed
via the serial port or one of the default values (8 or 128) can be selected if the
user has performed default programming.
As mentioned, every queue within a multi-queue device has its own almost
full status, when a queue is selected on the write port, this status is output via the
PAF flag. The PAF flag value for each queue is programmed during multi-queue
device programming (along with the number of queues, queue depths and
almost empty values). The PAF offset value, m, for a respective queue can be
programmed to be anywhere between ‘0’ and ‘D’, where ‘D’ is the total memory
depth for that queue. The PAF value of different queues within the same device
can be different values.
When queue switches are being made on the write port, the PAF flag output
will switch to the new queue and provide the user with the new queue status,
on the second cycle after a new queue selection is made, on the same WCLK
cycle that data can actually be written to the new queue. That is, a new queue
can be selected on the write port via the WRADD bus, WADEN enable and a
rising edge of WCLK. On the second rising edge of WCLK following a queue
selection, the PAF flag output will show the full status of the newly selected queue.
The PAF is flag output is double register buffered, so when a write operation
occurs at the almost full boundary causing the selected queue status to go almost
full the PAF will go LOW 2 WCLK cycles after the write. The same is true when
a read occurs, there will be a 2 WCLK cycle delay after the read operation.
So the PAF flag delays are:
from a write operation to PAF flag LOW is 2 WCLK + t
WAF
The delay from a read operation to PAF flag HIGH is tSKEW2 +WCLK + tWAF
Note, if tSKEW is violated there will be one added WCLK cycle delay.
The PAF flag is synchronous to the WCLK and all transitions of the PAF flag
occur based on a rising edge of WCLK. Internally the multi-queue device
monitors and keeps a record of the almost full status for all queues. It is possible
that the status of a PAF flag maybe changing internally even though that flag is
not the active queue flag (selected on the write port). A queue selected on the
read port may experience a change of its internal almost full flag status based
on read operations. The multi-queue flow-control device also provides a
duplicate of the PAF flag on the PAF[7:0] flag bus, this will be discussed in detail
in a later section of the data sheet.
See Figures 18 and 19 for Almost Full flag timing and queue switching.
ALMOST EMPTY FLAG
As previously mentioned the multi-queue flow-control device provides a
single Programmable Almost Empty flag output, PAE. The PAE flag output
provides a status of the almost empty condition for the active queue currently
selected on the read port for read operations. Internally the multi-queue flow-
control device monitors and maintains a status of the almost empty condition of
all queues within it, however only the queue that is selected for read operations
has its empty status output to the PAE flag. This dedicated flag is often referred
to as the “active queue almost empty flag”. The position of the PAE flag boundary
21
IDT72V51433/72V51443/72V51453 3.3V, MULTI-QUEUE FLOW-CONTROL DEVICES
(16 QUEUES) 18 BIT WIDE CONFIGURATION 589,824, 1,179,648 and 2,359,296 bits
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
within a queue can be at any point within that queues depth. This location can
be user programmed via the serial port or one of the default values (8 or 128)
can be selected if the user has performed default programming.
As mentioned, every queue within a multi-queue device has its own almost
empty status, when a queue is selected on the read port, this status is output via
the PAE flag. The PAE flag value for each queue is programmed during multi-
queue device programming (along with the number of queues, queue depths
and almost full values). The PAE offset value, n, for a respective queue can be
programmed to be anywhere between ‘0’ and ‘D’, where ‘D’ is the total memory
depth for that queue. The PAE value of different queues within the same device
can be different values.
When queue switches are being made on the read port, the PAE flag output
will switch to the new queue and provide the user with the new queue status,
on the second cycle after a new queue selection is made, on the same RCLK
cycle that data actually falls through to the output register from the new queue.
That is, a new queue can be selected on the read port via the RDADD bus,
RADEN enable and a rising edge of RCLK. On the second rising edge of RCLK
following a queue selection, the data word from the new queue will be available
at the output register and the PAE flag output will show the empty status of the
newly selected queue. The PAE is flag output is double register buffered, so
when a read operation occurs at the almost empty boundary causing the
selected queue status to go almost empty the PAE will go LOW 2 RCLK cycles
after the read. The same is true when a write occurs, there will be a 2 RCLK
cycle delay after the write operation.
So the PAE flag delays are:
from a read operation to PAE flag LOW is 2 RCLK + tRAE
The delay from a write operation to PAE flag HIGH is tSKEW2 + RCLK + tRAE
Note, if tSKEW is violated there will be one added RCLK cycle delay.
The PAE flag is synchronous to the RCLK and all transitions of the PAE flag
occur based on a rising edge of RCLK. Internally the multi-queue device
monitors and keeps a record of the almost empty status for all queues. It is possible
that the status of a PAE flag maybe changing internally even though that flag is
not the active queue flag (selected on the read port). A queue selected on the
write port may experience a change of its internal almost empty flag status based
on write operations. The multi-queue flow-control device also provides a
duplicate of the PAE flag on the PAE[7:0] flag bus, this will be discussed in detail
in a later section of the data sheet.
See Figures 20 and 21 for Almost Empty flag timing and queue switching.

72V51453L7-5BBI

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Description:
IC MULTI-QUEUE FLOW-CTRL 256BGA
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