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Электронный компонент: 72V8985

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1
2003 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
MAY 2003
3.3 VOLT TIME SLOT INTERCHANGE
DIGITAL SWITCH
256 x 256
IDT72V8985
DSC-5707/4
IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc. The ST-BUS
is a trademark of Mitel Corp.
FUNCTIONAL BLOCK DIAGRAM
FEATURES:
256 x 256 channel non-blocking switch
Automatic signal identification (ST-BUS
, GCI)
8 RX inputs--32 channels at 64 Kbit/s per serial line
8 TX outputs--32 channels at 64 Kbit/s per serial line
Three-state serial outputs
Microprocessor Interface (8-bit data bus)
Frame Integrity for data applications
3.3V Power Supply
Available in 44-pin Plastic Leaded Chip Carrier (PLCC),
48-pin Small Shrink Outline Package (SSOP), and 44-pin Plastic
Quad Flatpack (PQFP)




Operating Temperature Range -40


C to +85C




3.3V I/O with 5V Tolerant Inputs
DESCRIPTION:
The IDT72V8985 is a ST-BUS
/GCI compatible digital switch controlled by
a microprocessor. The IDT72V8985 can handle as many as 256, 64 Kbit/s input
and output channels. Those 256 channels are divided into 8 serial inputs and
outputs, each of which consists of 32 channels. The IDT72V8985 provides per-
channel variable or constant throughput delay modes and microprocessor read
and write access to individual channels. As an important function of a digital
switch is to maintain sequence integrity and minimize throughput delay, the
IDT72V8985 is an ideal solution for most switching needs.
FUNCTIONAL DESCRIPTION
Frame sequence, constant throughput delay, and guaranteed minimum
delay are high priority requirements in today's integrated data and multimedia
networks. The IDT72V8985 provides these functions on a per-channel basis
using a standard microprocessor control interface. Each of the eight serial lines
is designed to switch 64 Kbit/s PCM or N x 64 Kbit/s data.
In Processor Mode, the microprocessor can access the input and output time
slots to control other devices such as ISDN transceivers and trunk interfaces.
Supporting both GCI and ST-BUS
formats, IDT72V8985 has incorporated an
internal circuit to automatically identify the polarity and format of the frame
synchronization.
A functional block diagram of the IDT72V8985 device is shown on page 1.
The serial streams operate continuously at 2.048 Mb/s and are arranged in
125
s wide frames each containing 32, 8-bit channels. Eight input (RX0-7) and
eight output (TX0-7) serial streams are provided in the IDT72V8985 device
allowing a complete 256 x 256 channel non-blocking switch matrix to be
constructed. The serial interface clock for the device is 4.096 MHz.
Microprocessor Interface
Control Register
Timing
Unit
RX0
RX1
RX2
RX3
RX4
RX5
RX6
RX7
TX0
TX1
TX2
TX3
TX4
TX5
TX6
TX7
ODE
F0i
C4i
V
CC
CS
DS
R/
W A0/
A5
GND
CCO
DTA D0/
D7
5707 drw01
Receive
Serial Data
Streams
Data
Memory
Output MUX
Connection
Memory
Transmit
Serial Data
Streams
RESET
(1)
NOTE:
1. The
RESET Input is only provided on the SSOP package.
2
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
35
34
33
32
31
30
29
37
36
3
2
44
1
43
42
41
5
4
6
5707 drw02
INDEX
38
39
40
21
22
24
23
25
26
27
19
20
18
28
DS
CS
R/
W
11
12
13
14
15
16
17
9
10
8
7
RX2
RX1
RX0
DTA
TX0
TX1
TX2
DNC
(1)
CCO
ODE
TX3
TX4
TX5
TX6
TX7
GND
D
0
RX3
RX4
RX5
RX6
RX7
V
CC
F0i
C4i
A
0
D
1
D
2
D
3
D
4
A
1
A
2
DNC
(1)
DNC
(1)
DNC
(1)
D
5
D
6
D
7
A
5
A
4
A
3
PIN CONFIGURATION
PLCC: 0.05in. pitch, 0.65in. x 0.65in
(J44-1, order code: J)
TOP VIEW
TOP VIEW
DTA
CCO
ODE
1
2
40
39
TX0
3
38
TX1
4
37
TX2
5
36
TX3
6
35
TX4
7
34
TX5
8
33
TX6
9
32
TX7
10
31
GND
11
30
12
29
CS
13
28
14
27
15
16
17
18
19
20
26
25
RX1
RX2
RX3
RX4
RX5
RX6
F0i
R/
W
DS
C4i
V
CC
RX7
RX0
21
22
23
2
4
48
47
46
45
44
43
42
41
GND
RESET
(2)
GND
5707 drw04
DNC
(1)
A
0
D
0
DNC
(1)
DNC
(1)
DNC
(1)
V
CC
D
1
D
2
D
3
D
4
D
5
D
6
D
7
A
1
A
2
A
3
A
5
A
4
NOTES:
1. DNC - Do Not Connect
2. The
RESET Input is only provided on the SSOP package.
PQFP: 0.80mm pitch, 10mm x 10mm
(DB44-1, order code: DB)
TOP VIEW
29
28
27
26
25
24
23
31
30
44
43
42
41
5707 drw03
INDEX
32
33
40
DS
CS
R/
W
5
6
7
8
9
10
11
3
4
2
1
RX2
RX1
RX0
DTA
TX0
TX1
TX2
DNC
(1)
CCO
ODE
TX3
TX4
TX5
TX6
TX7
GND
D
0
RX3
RX4
RX5
RX6
RX7
V
CC
F0i
C4i
A
0
D
1
D
2
D
3
D
4
A
1
A
2
DNC
(1)
DNC
(1)
DNC
(1)
D
5
D
6
D
7
A
5
A
4
A
3
39
38
37
36
35
34
12
13
14
15
16
17
18
19
20
21
22
Package Type
Reference Identifier
Order Code
SSOP: 0.025in. pitch, 0.625in. x 0.295in.
SO48-1
PV
3
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
PIN DESCRIPTIONS
SYMBOL
NAME
I/O
DESCRIPTION
GND
Ground.
Ground Rail.
V
CC
V
CC
+3.3 Volt Power Supply.
DTA
Data Acknowledgment
O
This active LOW output indicates that a data bus transfer is complete. A pull-up resistor is required at this
(Open Drain)
output.
RX0-7
RX Input 0 to 7
I
Serial data input streams. These streams have 32 channels at data rates of 2.048 Mb/s.
F0i
Frame Pulse
I
This input accepts and automatically identifies frame synchronization signals formatted according to different
backplane specifications such as ST-BUS
and
GCI.
C4i
Clock
I
4.096 MHz serial clock for shifting data in and out of the data streams.
A0-A5
Address 0 to 5
I
These lines provide the address to IDT72V8985 internal registers.
DS
Data Strobe
I
This is the input for the active HIGH data strobe on the microprocessor interface. This input operates with
CS to enable the internal read and write generation.
R/
W
Read/Write
I
This input controls the direction of the data bus lines (D0-D7) during a microprocessor access.
CS
Chip Select
I
Active LOW input enabling a microprocessor read or write of control register or internal memories.
D0-D7
Data Bus 0 to 7
I/O
These pins provide microprocessor access to data in the internal control register. Connection Memory HIGH,
Connection Memory LOW and data memory.
TX0-7
TX Outputs 0 to 7
O
Serial data output streams. These streams are composed of 32, 64 Kbit/s channels at data rates of 2.048 Mb/s.
(Three-state Outputs)
ODE
Output Drive Enable
I
This is an output enable for the TX0-7 serial outputs. If this input is LOW, TX0-7 are high-impedance. If this is
HIGH, each channel may still be put into high-impedance by software control.
CCO
Control Channel Output
O
This output is a 2.048 Mb/s line which contains 256 bits per frame. The level of each bit is controlled by the
contents of the CCO bit in the Connection Memory HIGH locations.
RESET
Device Reset
I
This input (active LOW) puts the IDT72V8985 in its reset state that clears the device internal counters,
(Schmitt Trigger Input)
registers and brings TX0-7 and microport data outputs to a high-impedance state. The time constant for a
power up reset circuit must be a minimum of five times the rise time of the power supply. In normal operation,
the
RESET pin must be held LOW for a minimum of 100ns to reset the device.
4
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
The received serial data is internally converted to parallel by the on chip
serial-to-parallel converters and stored sequentially in a 256-position Data
Memory. By using an internal counter that is reset by the input 8 KHz frame pulse,
F0i, the incoming serial data streams can be framed and sequentially addressed.
Depending on the type of information to be switched, the IDT72V8985 device
can be programmed to perform time slot interchange functions with different
throughput delay capabilities on a per-channel basis. The Variable Delay
mode, most commonly used for voice applications, can be selected ensuring
minimum throughput delay between input and output data. In Constant Delay
mode, used in multiple or grouped channel data applications, the integrity of the
information through the switch is maintained.
CONNECTION MEMORY
Data to be output on the serial streams may come from two sources: Data
Memory or Connection Memory. The Connection Memory is split into HIGH
and LOW parts and is associated with particular TX output streams. In Processor
Mode, data output on the TX streams is taken from the Connection Memory Low
and originates from the microprocessor (Figure 2). Where as in Connection
Mode (Figure 1), data is read from Data Memory and originated from the
incoming RX streams. Data destined for a particular channel on the serial output
stream is read internally during the previous channel time slot to allow time for
memory access and internal parallel-to-serial conversion.
CONNECTION MODE
In Connection Mode, the addresses of input source for all output channels
are stored in the Connection Memory Low. The Connection Memory Low
locations are mapped to corresponding 8-bit x 32-channel output. The contents
of the Data Memory at the selected address are then transferred to the parallel-
to-serial converters before being output. By having the output channel to specify
the input channel through the Connection Memory, input channels can be
broadcast to several output channels.
PROCESSOR MODE
In Processor Mode the CPU writes data to the Connection Memory Low
locations which correspond to the output link and channel number. The contents
of the Connection Memory Low are transferred to the parallel-to-serial
converter one channel before it is to be output and are transmitted each frame
to the output until it is changed by the CPU.
CONTROL
The Connection Memory High bits (Table 4) control the per-channel
functions available in the IDT72V8985. Output channels are selected into
specific modes such as: Processor Mode or Connection mode, Variable or
Constant throughput delay modes, Output Drivers Enabled or in three-state
condition. There is also one bit to control the state of the CCO output pin.
OUTPUT DRIVE ENABLE (ODE)
The ODE pin is the master output three-state control pin. If the ODE input
is held LOW all TDM (Time Division Multiplexed) outputs will be placed in high
impedance regardless Connection Memory High programming. However, if
ODE is HIGH, the contents of Connection Memory High control the output state
on a per-channel basis.
SERIAL INTERFACE TIMING
The IDT72V8985 master clock (
C4i) is 4.096 MHz signal allowing serial data
link configuration at 2.048 Mb/s to be implemented. The IDT72V8985 can
automatically detect the presence of an input frame pulse, identify the type of
backplane present on the serial interface, and format the synchronization pulse
according to ST-BUS
or GCI interface specifications (active HIGH in GCI or
active LOW in ST-BUS
). Upon determining the correct interface Connected
to the serial port, the internal timing unit establishes the appropriate serial data
bit transmit and sampling edges. In ST-BUS
mode, every second falling edge
of the 4.096 MHz clock marks a boundary and the input data is clocked in by
the rising edge, three quarters of the way into the bit cell. In GCI mode every
second rising edge of the 4.096 MHz clock marks the bit boundary while data
sampling is performed during the falling edge, at three quarters of the bit
boundaries.
DELAY THROUGH THE IDT72V8985
The transfer of information from the input serial streams to the output serial
streams results in a delay through the device. The delay through the
IDT72V8985 device varies according to the mode selected in the
V/C bit of the
Connection Memory High.
VARIABLE DELAY MODE
The delay in Variable Delay Mode is dependent only on the combination
of source and destination on the input and output streams. The minimum delay
achievable in the IDT72V8985 device is three time slots. In the IDT72V8985
device, the information that is to be output in the same channel position as the
information is input (position n), relative to frame pulse, will be output in the
following frame (channel n, frame n+1). The same occurs if the input channels
succeeding (n+1, n+2) the channel position as the information is input.
The information switched to the third time slot after the input has entered the
device (for instance, input channel 0 to output channel 3 or input channel 30 to
output channel 1), is always output three channels later.
Any switching configuration that provides three or more time slots between
input and output channels, will have a throughput delay equal to the difference
between the output and input channels; i.e., the throughput delay will be less
than one frame. Table 1 shows the possible delays for the IDT72V8985 device
in Variable Delay Mode. An example is shown in Figure 3.
CONSTANT DELAY MODE
In this mode frame integrity is maintained in all switching configurations by
Figure 2. Processor Mode
Figure 1. Connection Mode
Receive
Serial Data
Streams
5707 drw05
RX
TX
Transmit
Serial Data
Streams
Data
Memory
Connection
Memory
5707 drw06
TX
Microprocessor
Receive
Serial Data
Streams
Transmit
Serial Data
Streams
Data
Memory
Connection
Memory
FUNCTIONAL DESCRIPTION (Cont'd)
5
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
making use of a multiple Data Memory buffer technique where input channels
written in any of the buffers during frame N will be read out during frame N+2.
In the IDT72V8985, the minimum throughput delay achievable in Constant
Delay mode will be 32 time slots; for example, when input time slot 32 (channel
31) is switched to output time slot 1 (channel 0). Likewise, the maximum delay
is achieved when the first time slot in a frame (channel 0) is switched to the last
time slot in the frame (channel 31), resulting in 94 time slots of delay (see
Figure 4).
To summarize, any input time slot from input frame N will be always switched
to the destination time slot on output frame N+2. In Constant Delay mode the
device throughput delay is calculated according to the following formula:
DELAY=[32+(32-IN)+(OUT-1)]
IN =the number of the input time slot (from 1 to 32)
OUT = the number of the output time slot (from 1 to 32).
MICROPROCESSOR PORT
The IDT72V8985 microprocessor port is a non-multiplexed bus architec-
ture. The parallel port consists of an 8-bit parallel data bus (D0-D7), six address
input lines (A0-A5) and four control lines (
CS, DS, R/W and DTA). This parallel
microport allows the access to the Control Registers, Connection Memory Low,
Connection Memory High, and the Data Memory. All locations are read/written
except for the Data Memory, which can be read only.
Accesses from the microport to the Connection Memory and the Data
Memory are multiplexed with accesses from the input and output TDM ports.
This can cause variable Data Acknowledge delays (
DTA). In the IDT72V8985
device, the
DTA output provides a maximum acknowledgment delay of 800ns
for read/write operations in the Connection Memory. However, for operations
in the Data Memory (Processor Mode), the maximum acknowledgment delay
can be 1220ns.
SOFTWARE CONTROL
If the A5, A1, A0 address line inputs are LOW then the IDT72V8985 Internal
Control Register is addressed (see Table 2). If A5 input line is high, then the
remaining address input lines are used to select the 32 possible channels per
input or output stream. As explained in the Control Register description, the
address input lines and the Stream Address bits (STA) of the Control register
give the user the capability of selecting all positions of IDT72V8985 Data and
Connect memories. See Figure 5 for accessing internal memories.
The data in the control register consists of Memory Select and Stream
Address bits, Split Memory and Processor Enable bits (Table 3). In Split Memory
mode (Bit 7 of the Control register) reads are from the Data Memory and writes
are to the Connection Memory LOW. The Memory Select bits allow the
Connection Memory High or LOW or the Data Memory to be chosen, and the
Stream Address bits define internal memory subsections corresponding to input
or output streams.
The Processor Enable bit (bit 6) places every output channel on every
output stream in Processor Mode; i.e., the contents of the Connection Memory
LOW (CML, see Table 5) are output on the output streams once every frame
unless the ODE input pin is LOW. If PE bit is HIGH, then the IDT72V8985
behaves as if bits 2 (Channel Source) and 0 (Output Enable) of every
Connection Memory High (CMH, see Table 4) locations were set to HIGH,
regardless of the actual value. If PE is LOW, then bit 2 and 0 of each Connection
Memory High location operates normally. In this case, if bit 2 of the CMH is HIGH,
the associated TX output channel is in Processor Mode. If bit 2 of the CMH is
LOW, then the contents of the CML define the source information (stream and
channel) of the time slot that is to be switched to an output.
If the ODE input pin is LOW, then all the serial outputs are high-impedance.
If ODE is HIGH, then bit 0 (Output Enable) of the CMH location enables (if HIGH)
or disables (if LOW) for that particular channel.
The contents of bit 1 (CCO) of each Connection Memory High Location (see
Table 4) is output on CCO pin once every frame. The CCO pin is a 2.048 Mb/
s output, which carries 256 bits. If CCO bit is set HIGH, the corresponding bit
on CCO output is transmitted HIGH. If CCO is LOW, the corresponding bit on
the CCO output is transmitted LOW. The contents of the 256 CCO bits of the CMH
are transmitted sequentially on to the CCO output pin and are synchronous to
the TX streams. To allow for delay in any external control circuitry the contents
of the CCO bit is output one channel before the corresponding channel on the
TX streams. For example, the contents of CCO bit in position 0 (corresponding
to TX0, CH0), is transmitted synchronously with the TX channel 31, bit 7. Bit 1's
of CMH for channel 1 of streams 0-7 are output synchronously with TX channel
0 bits 7-0.
INITIALIZATION
During the microprocessor initialization routine, the microprocessor should
program the desired active paths through the matrices, and put all other channels
into the high impedance state. Care should be taken that no two Connected TX
outputs drive the bus simultaneously. With the CMH setup, the microprocessor
controlling the matrices can bring the ODE signal high to relinquish high
impedance state control to the Connection Memory High bits outputs.
The reset pin is designed to be used with board reset circuitry. During reset
the TX serial streams will be put into high-impedance and the state of internal
registers and counters will be reset. As the connection memory can be in any
state after a power up, the ODE pin should be used to hold the TX streams in
high-impedance until the per-channel output enable control in the connection
memory high is appropriately programmed. The main difference between ODE
and reset is, reset alters the state of the registers and counters where as ODE
controls only the high-impedance state of the TX streams.
RESET input is only
provided on the SSOP packages.
TABLE 1
VARIABLE DELAY MODE
Input Channel
Output Channel
Throughput Delay
n
m=n, n+1 or n+2
m-n+32 time slot
n
m>n+2
m-n time slot
n
m<n
32-(n-m) time slot
TABLE 2
ADDRESS MAPPING
A5
A4
A3
A2
A1
A0
LOCATION
0
X
X
X
0
0
Control Register
1
0
0
0
0
0
Channel 0
1
0
0
0
0
1
Channel 1
1
1
1
1
1
1
1
1
1
1
1
Channel 31
6
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
For Slot 1 ("A"): IN=32, OUT=1, DELAY=(32-32)+32+(1-1)=32 time slots minimum delay
For Slot 32 ("J"): IN=1, OUT=32, DELAY=(32-1)+32+(32-1)=94 time slots maximum delay
Figure 4. Constant Delay Mode
A B C D E F G H I J
32 Slots
32 Slots
32 Slots
32 31.........7 6 5 4 3 2 1 Time Slot
Outgoing Now
Incoming Now
Outgoing Next
32 31........7 6 5 4 3 2
1
G H
I J
J
32 Slots
32 Slots
32 Slots
5706 drw07
Outgoing
Incoming
Switching
J I H G F E D C B A
J J
Time Slot 32 31 30 29 28............ 3 2 1
32 31 30 29 28............. 3 2 1 Time Slot
A B C D E F G H I J
Time Slot 32 31 30 29 28............ 3 2 1
Figure 3. Variable Delay Mode
For J: DELAY=3 Slots, 32 Slots, 33 Slots, and 34 Slots
For G, H, and I: DELAY= 3 slots
7
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
Connection Memory High
Connection Memory Low
Channel 0
Channel 1
Channel 2
Channel 31
Channel 0
Channel 1
Channel 2
Channel 31
Channel 0
Channel 1
Channel 2
Channel 31
Channel 0
Channel 1
Channel 2
Channel 31
Channel 0
Channel 1
Channel 2
Channel 31
Channel 0
Channel 1
Channel 2
Channel 31
Channel 0
Channel 1
Channel 2
Channel 31
Channel 0
Channel 1
Channel 2
Channel 31
100001
100010
111111
Data Memory
0
0
0
0
0
0
1
1
0
1
0
2
0
1
1
3
1
0
0
4
1
0
1
5
1
1
0
6
1
1
1
7
Stream
0
1
1
0
1
1
Control Register
CR
b
7
External Address Bits A5-A0
5707
drw08
100000
The Control Register is only accessed when A5=0.
All other address bits have no effect when A5=0.
When A5 =1, only 32 bytes are randomly accessable
via A0-A4 at any one instant. Which 32 bytes are
accessed is determined by the state of CRb0 -CRb4.
The 32 bytes correlate to 32 channel of one ST-BUS
stream.
CR
b
6
CR
b
5
CR
b
4
CR
b
3
CR
b
2
CR
b
1
CR
b
0
CR
b
4
CR
b
3
CR
b
2
CR
b
1
CR
b
0
Figure 5. Addressing Internal Memories
8
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
TABLE 4
CONNECTION MEMORY HIGH
TABLE 5
CONNECTION MEMORY LOW
TABLE 3
CONTROL REGISTER
Bit
Name
Description
7
SM (Split Memory)
When 1, all subsequent reads are from the Data Memory and writes are to the Connection Memory, except when
the Control Register is accessed again. The Memory Select bits need to specify the memory for the operations.
6
PE (Processor Mode)
When 1, the contents of the Connection Memory LOW are output on the Serial Output streams except when in high-
impedance. When 0, the Connection Memory bits for each channel determine what is output.
5
unused
4-3
MS1-MS0
0-0 - Not to be used.
(Memory Select Bits)
0-1 - Data Memory (read only from the CPU)
1-0 - Connection Memory LOW
1-1 - Connection Memory is HIGH
2-0
STA2-0
The number expressed in binary notation on these bits refers to the input or output stream which corresponds to the
(Stream Address Bits)
subsection of memory made accessible for subsequent operations.
SM
PE
X
MS1
MS0
STA2
STA1
STA0
7
6
5
4
3
2
1
0
x = don't care
Bit
Name
Description
7,5,4,3
unused
6
V/C (Variable/Constant
This bit is used to select between Variable (LOW) and Constant Delay (HIGH) modes on a per-channel basis.
Throughput Delay Mode)
2
CS
When 1, the contents of the corresponding location in Connection Memory LOW are output on the location's channel
(Channel Source)
and stream. When 0, the contents of the corresponding location in Connection Memory LOW act as an address for the
Data Memory and determine the source of the connection to the location's channel and stream.
1
CCO (CCO Bit)
This bit drives a bit time on the CCO output pin.
0
OE (Output Enable)
This bit enables the output drivers on a per-channel basis. This allows individual channels on individual streams to
be made high-impedance, allowing switch matrices to be constructed. A HIGH enables the driver and a LOW disables it.
X
V/C
X
X
X
CS
CCO
OE
7
6
5
4
3
2
1
0
x = don't care
Bit
Name
Description
7-5
SAB2-0
(1)
These three bits are used to select eight source streams for the Connection.
(Source Stream Address Bits)
4-0
(1)
CAB2-0
(1)
These five bits are used to select 32 different source channels for the Connection (the stream where the channel
(Source Channel Address Bits) is present is defined by bits SAB2-0). Bit 4 is the most significant bit.
SAB2
SAB1
SAB0
CAB4
CAB3
CAB2
CAB1
CAB0
NOTE:
1. If bit 2 of the corresponding Connection HIGH location is 1 or bit 6 of the Control Register is 1, then these entire 8 bits are output on the channel and stream associated with
this location. Otherwise, the bits are used as indicated to define the source of the Connection which is output on the channel and stream associated with this location.
7
6
5
4
3
2
1
0
9
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
Test Point
Output
Pin
C
L
GND
S
1
R
L
VCC
GND
5707 drw09
S
2
S1 is open circuit except when testing output
levels or high impedance states.
S2 is switched to V
CC
or GND when testing
output levels or high impedance states.
Figure 6. Output Load
RECOMMENDED OPERATING
CONDITIONS
DC ELECTRICAL CHARACTERISTICS
NOTE:
1. Typical figures are at 25
C and are for design aid only; not guaranteed and not subject
to production testing.
NOTE:
1. Typical figures are at 25
C and are for design aid only; not guaranteed and not subject to production testing.
Symbol
Parameter
Min.
Max.
Unit
V
CC
- GND
-0.3
5.0
V
Vi
Voltage on Digital Inputs
GND - 0.3
V
CC
+0.3
V
V
O
Voltage on Digital Outputs
GND - 0.3
V
CC
+0.3
V
I
O
Current at Digital Outputs
20
mA
T
S
Storage Temperature
-55
+125
C
P
D
Package Power Dissapation
1
W
Symbol
Parameter
Min.
Typ.
(1)
Max.
Unit
V
CC
Positive Supply
3.0
3.3
3.6
V
V
I
Input Voltage
0
V
CC
V
T
OP
Operating Temperature
-40
25
+85
C
Commercial
Symbol
Parameter
Min.
Typ.
(1)
Max.
Units
Test Conditions
I
CC
Supply Current
3
5
mA
Outputs Unloaded
V
IH
Input High Voltage
2.0
V
V
IL
Input Low Voltage
0.8
V
I
IL
Input Leakage (Inputs)
15
A
V
I
between GND and V
CC
C
I
Input Capacitance
10
pF
V
OH
Output High Voltage
2.4
V
I
OH
= 10mA
I
OH
Output High Current
10
mA
Sourcing. V
OH
= 0.8V
V
OL
Output Low Voltage
0.4
V
I
OL
= 5mA
I
OL
Output Low Current
5
mA
Sinking. V
OL
= 0.4V
I
OZ
High Impedance Leakage
5
A
V
O
between GND and V
CC
C
O
Output Pin Capacitance
10
pF
NOTE:
1. Exceeding these values may cause permanent damage. Functional operation under
these conditions is not implied.
ABSOLUTE MAXIMUM RATINGS
(1)
10
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
Figure 7. ST-BUS
Timing
F0i
C4i
TX
RX
5707 drw10
Ch. 31, Bit 0
Ch. 0, Bit 7
Ch. 0, Bit 6
Ch. 0, Bit 6
Ch. 0, Bit 7
Ch. 31, Bit 0
Ch. 0,
Bit 5
t
F0iW
Ch. 0, Bit 5
t
F0iH
t
F0iS
t
DAA
t
C4i
t
STiS
t
STiH
t
CH
t
CL
t
f
t
r
AC ELECTRICAL CHARACTERISTICS
(1)
ST-BUS
TIMING
NOTE:
1. Timing is over recommended temperature and power supply voltages.
2. Typical figures are at 25
C and are for design aid only; not guaranteed and not subject to production testing.
Symbol
Parameter
Min.
Typ.
(2)
Max.
Units
Test Conditions
t
F0iW
Frame Pulse Width
244
ns
t
F0iS
Frame Pulse Setup Time
5
20
190
ns
t
F0iH
Frame Pulse Hold Time
5
20
190
ns
t
DAA
TX delay Active to Active
40
60
ns
C
L
= 150pF
t
STiS
RX Setup Time
10
ns
t
STiH
RX Hold Time
10
ns
t
C4i
Clock Period
244
ns
t
CL
CK Input Low
122
ns
t
CH
CK Input High
122
ns
tr, tf
Clock Rise/Fall Time
10
ns
11
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
Figure 8. GCI Timing
t
DAA
TX
RX
5707 drw11
t
STiS
t
STiH
t
WFH
F0i
C4i
t
CH
t
CL
t
f
t
r
t
C4i
Ch. 31
Bit 7
Ch. 0
Bit 0
Ch. 0
Bit 1
Ch. 0
Ch. 0
Bit 1
Bit 0
Ch. 31
Bit 7
t
F0iS
t
F0iH
AC ELECTRICAL CHARACTERISTICS
(1)
GCI TIMING
NOTE:
1. Timing is over recommended temperature and power supply voltages.
2. Typical figures are at 25
C and are for design aid only; not guaranteed and not subject to production testing.
Symbol
Parameter
Min.
Typ.
(2)
Max.
Units
Test Conditions
t
C4i
Clock Period
244
ns
tCL, tCH
Pulse Width
122
ns
t
WFH
Frame Width High
244
ns
t
F0iS
Frame Setup
5
20
190
ns
t
F0iH
Frame Hold
5
20
190
ns
t
DAA
Data Delay/Clock Active to Active
40
60
ns
C
L
= 150pF
t
STiS
RX Input Setup
10
ns
t
STiH
RX Input Hold
10
ns
tr, tf
Clock Rise/Fall Time
10
ns
12
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
C4i
TX0-7
CCO
5707 drw12
TX0-7
(GCI)
(ST-BUS
)
Bit Cell Boundary
t
TAZ
t
XCD
t
TZA
Figure 9. Serial Outputs and External Control
Figure 10. Output Driver Enable
t
OED
ODE
TX0-7
5707 drw13
t
OED
Figure 11. Reset
RS
TX
5707 drw14
t
ZDO
t
ZRS
t
RSZ
t
RPW
AC ELECTRICAL CHARACTERISTICS
(1)
SERIAL STREAM TIMING
Symbol
Characteristics
Min.
Typ.
(2)
Max.
Unit
Test Conditions
t
TAZ
TX0-7 Delay - Active to High Z
30
45
ns
R
L
= 1K
(3)
, C
L
= 150pF
t
TZA
TX0-7 Delay - High Z to Active
45
60
ns
C
L
= 150pF
t
OED
Output Driver Enable Delay
45
60
ns
R
L
= 1K
(3)
, C
L
= 150pF
t
XCD
CCO Output Delay
0
40
60
ns
C
L
= 150pF
t
RSZ
Reset to High Z
5
30
ns
t
ZRS
High Z to Reset
0
ns
t
ZDO
High Z to Valid Data
32
cycles
C4i cycles
t
RPW
Reset Pulse Width
100
ns
R
L
= 1K
(3)
, C
L
= 150pF
NOTE:
1. Timing is over recommended temperature and power supply voltages.
2. Typical figures are at 25
C and are for design aid only; not guaranteed and not subject to production testing.
3. High Impedance is measured by pulling to the appropriate rail with R
L
, with timing corrected to cancel time taken to discharge C
L
.
13
Commercial Temperature Range
IDT72V8985 3.3V Time Slot Interchange
Digital Switch 256 x 256
Figure 12. Motorola Non-Multiplexed Bus Timing
CS
DS
D0-D7
WRITE
5707 drw15
R/
W
A0-A5
D0-D7
READ
DTA
VALID DATA
VALID DATA
t
CSS
t
RWS
t
ADS
t
CSH
t
RWH
t
ADH
t
DHR
t
DSW
t
SWD
t
DDR
t
AKD
t
DHW
t
AKH
AC ELECTRICAL CHARACTERISTICS
(1)
MICROPROCESSOR TIMING
Symbol
Characteristics
Min.
Typ.
(2)
Max.
Unit
Test Conditions
t
CSS
CS Setup from DS Rising
0
ns
t
RWS
R/
W Setup from DS Rising
5
ns
t
ADS
Add Setup from DS Rising
5
ns
t
CSH
CS Hold after DS Falling
0
ns
t
RWH
R/
W Hold after DS Falling
5
ns
t
ADH
Add Hold after DS Falling
5
ns
t
DDR
Data Setup from
DTA Low on Read
10
ns
C
L
= 150pF
t
DHR
Data Hold on Read
10
50
90
ns
R
L
= 1K
(3)
, C
L
= 150pF
t
DSW
Data Setup on Write (Fast Write)
10
ns
t
SWD
Valid Data Delay on Write (Slow Write)
122
ns
t
DHW
Data Hold on Write
5
ns
t
AKD
Acknowledgment Delay:
C
L
= 150pF
Reading Data Memory
560
1220
ns
Reading/Writing Connection Memory
300/370
730/800
ns
Writing to Control Register
45
70
ns
Reading to Control Register
45
70
ns
t
AKH
Acknowledgment Hold Time
10
20
40
ns
R
L
= 1K
(3)
, C
L
= 150pF
NOTE:
1. Timing is over recommended temperature and power supply voltages.
2. Typical figures are at 25
C and are for design aid only; not guaranteed and not subject to production testing.
3. High Impedance is measured by pulling to the appropriate rail with R
L
, with timing corrected to cancel time taken to discharge C
L
.
14
CORPORATE HEADQUARTERS
for SALES:
for Tech Support:
2975 Stender Way
800-345-7015 or 408-727-6116
408-330-1753
Santa Clara, CA 95054
fax: 408-492-8674
email: TELECOMhelp@idt.com
www.idt.com
5707 drw15
XXXXXX
IDT
Device Type
X
Package
Process/
Temperature
Range
XX
BLANK
Commercial (-40
C to +85C)
72V8985 256 x 256
3.3V Time Slot Interchange Digital Switch
J
PV
DB
Plastic Leaded Chip Carrier (PLCC, J44-1)
Small Shrink Outline Package (SSOP, SO48-1)
Plastic Quad Flatpack (PQFP, DB44-1)
ORDERING INFORMATION
DATASHEET DOCUMENT HISTORY
5/24/2000
pgs. 1, 2, 13 and 14.
8/21/2000
pgs. 1, 2 and 14.
01/24/2001
pgs. 1 and 9.
04/05/2001
pg. 11
03/10/2003
pg. 13
05/09/2003
pgs. 1, 2, and 14