MITEL MT8980

MT8980D
ISO-CMOS ST-BUS FAMILY

Digital Switch
Features
ISSUE8
March 1997
Ordering Information
•
Mitel ST-BUS compatible
MT8980DE
MT8980DP
•
8-line x 32-channel inputs
•
8-line x 32-channel outputs
•
256 ports non-blocking switch
•
Single power supply (+5 V)
•
Low power consumption: 30 mW Typ.
•
Microprocessor-control interface
•
Three-state serial outputs
40 Pin Plastic DIP
44 Pin PLCC
-40°C to +85°C
Description
This VLSI ISO-CMOS device is designed for
switching PCM-encoded voice or
data, under
microprocessor control, in a modern digital
exchange, PBX or Central Office. It provides
simultaneous connections for up to 256 64 kbit/s
channels. Each of the eight serial inputs and outputs
consist of 32 64 kbit/s channels multiplexed to form a
2048 kbit/s ST-BUS stream. In addition, the MT8980
provides microprocessor read and write access to
individual ST-BUS channels.
C4i
F0i
VDD
VSS
Frame
Counter
STi0
ODE
Output
MUX
STi1
STi2
STi3
STi4
STi5
Serial
to
Parallel
Converter
Data
Memory
Control Register
Connection
Memory
STi6
STi7
DTA D7/
D0
STo1
Parallel
to
Serial
Converter
STo2
STo3
STo4
STo5
STo6
STo7
Control Interface
DS CS R/W A5/
A0
STo0
CSTo
Figure 1 - Functional Block Diagram
2-3
NC
STi2
STi1
STi0
DTA
CSTo
ODE
STo0
STo1
STo2
NC
MT8980D
6
5
4
3
2
1
44
43
42
41
40
DTA
STi0
STi1
STi2
STi3
STi4
STi5
STi6
STi7
VDD
F0i
C4i
A0
A1
A2
A3
A4
A5
DS
R/W
7
8
9
10
11
12
13
14
15
16
17
STo3
STo4
STo5
STo6
STo7
VSS
D0
D1
D2
D3
D4
39
38
37
36
35
34
33
32
31
30
29
NC
A3
A4
A5
DS
R/W
CS
D7
D6
D5
NC
18
19
20
21
22
23
24
25
26
27
28
STi3
STi4
STi5
STi6
STi7
VDD
F0i
C4i
A0
A1
A2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
CSTo
ODE
STo0
STo1
STo2
STo3
STo4
STo5
STo6
STo7
VSS
D0
D1
D2
D3
D4
D5
D6
D7
CS
40 PIN PLASTIC DIP
44 PIN PLCC
Figure 2 - Pin Connections
Pin Description
Pin #
Name
Description
40
DIP
44
PLCC
1
2
2-4
3-5
STi0- ST-BUS Input 0 to 2 (Inputs). These are the inputs for the 2048 kbit/s ST-BUS input
STi2 streams.
5-9
7-11
STi3- ST-BUS Input 3 to 7 (Inputs). These are the inputs for the 2048 kbit/s ST-BUS input
STi7 streams.
10
12
VDD
Power Input. Positive Supply.
11
13
F0i
Framing 0-Type (Input). This is the input for the frame synchronization pulse for the
2048 kbit/s ST-BUS streams. A low on this input causes the internal counter to reset on
the next negative transition of C4i.
12
14
C4i
4.096 MHz Clock (Input). ST-BUS bit cell boundaries lie on the alternate falling edges of this
clock.
1315
1517
A0-A2 Address 0 to 2 (Inputs). These are the inputs for the address lines on the microprocessor
interface.
1618
1921
A3-A5 Address 3 to 5 (Inputs). These are the inputs for the address lines on the microprocessor
interface.
19
22
DS
Data Strobe (Input). This is the input for the active high data strobe on the microprocessor
interface.
20
23
R/W
Read or Write (Input). This is the input for the read/write signal on the microprocessor
interface - high for read, low for write.
21
24
CS
Chip Select (Input). This is the input for the active low chip select on the microprocessor
interface
2-4
DTA
Data Acknowledgement (Open Drain Output). This is the data acknowledgement on the
microprocessor interface. This pin is pulled low to signal that the chip has processed the
data. A 909 Ω, 1/4W, resistor is recommended to be used as a pullup.
MT8980D
Pin Description (continued)
Pin #
Name
Description
40
DIP
44
PLCC
2224
2527
D7-D5 Data 7 to 5 (Three-state I/O Pins). These are the bidirectional data pins on the
microprocessor interface.
2529
2933
D4-D0 Data 4 to 0 (Three-state I/O Pins). These are the bidirectional data pins on the
microprocessor interface.
30
34
3135
3539
STo7- ST-BUS Output 7 to 3 (Three-state Outputs). These are the pins for the eight 2048
STo3 kbit/s ST-BUS output streams.
3638
4143
STo2- ST-BUS Output 2 to 0 (Three-state Outputs). These are the pins for the eight 2048
STo0 kbit/s ST-BUS output streams.
39
44
ODE Output Drive Enable (Input). If this input is held high, the STo0-STo7 output drivers function
normally. If this input is low, the STo0-STo7 output drivers go into their high impedance state.
NB: Even when ODE is high, channels on the STo0-STo7 outputs can go high impedance
under software control.
40
1
CSTo Control ST-BUS Output (Complementary Output). Each frame of 256 bits on this ST-BUS
output contains the values of bit 1 in the 256 locations of the Connection Memory High.
6, 18,
28,
40
VSS
NC
Power Input. Negative Supply (Ground).
No Connection.
2-5
MT8980D
Functional Description
Hardware Description
In recent years, there has been a trend in telephony
towards digital switching, particularly in association
with software control. Simultaneously, there has
been a trend in system architectures towards
distributed processing or multi-processor systems.
Serial data at 2048 kbit/s is received at the eight STBUS inputs (STi0 to STi7), and serial data is
transmitted at the eight ST-BUS outputs (STo0 to
STo7). Each serial input accepts 32 channels of
digital data, each channel containing an 8-bit word
which may represent a PCM-encoded analog/voice
sample as provided by a codec (e.g., MITEL’s
MT8964).
In accordance with these trends, MITEL has devised
the ST-BUS (Serial Telecom Bus).
This bus
architecture can be used both in software-controlled
digital voice and data switching, and for
interprocessor communications.
The uses in
switching and in interprocessor communications are
completely integrated to allow for a simple general
purpose architecture appropriate for the systems of
the future.
The serial streams of the ST-BUS operate
continuously at 2048 kbit/s and are arranged in 125
µs wide frames which contain 32 8-bit channels.
MITEL manufactures a number of devices which
interface to the ST-BUS; a key device being the
MT8980 chip.
The MT8980 can switch data from channels on STBUS inputs to channels on ST-BUS outputs, and
simultaneously allows its controlling microprocessor
to read channels on ST-BUS inputs or write to
channels on ST-BUS outputs (Message Mode). To
the microprocessor, the MT8980 looks like a memory
peripheral. The microprocessor can write to the
MT8980 to establish switched connections between
input ST-BUS channels and output ST-BUS
channels, or to transmit messages on output ST-BUS
channels.
By reading from the MT8980, the
microprocessor can receive messages from ST-BUS
input channels or check which switched connections
have already been established.
By integrating both switching and interprocessor
communications, the MT8980 allows systems to use
distributed processing and to switch voice or data in
an ST-BUS architecture.
This serial input word is converted into parallel data
and stored in the 256 X 8 Data Memory. Locations in
the Data Memory are associated with particular
channels on particular ST-BUS input streams. These
locations can be read by the microprocessor which
controls the chip.
Locations in the Connection Memory, which is split
into high and low parts, are associated with
particular ST-BUS output streams. When a channel
is due to be transmitted on an ST-BUS output, the
data for the channel can either be switched from an
ST-BUS input or it can originate from the
microprocessor. If the data is switched from an
input, then the contents of the Connection Memory
Low location associated with the output channel is
used to address the Data Memory. This Data
Memory address corresponds to the channel on the
input ST-BUS stream on which the data for switching
arrived. If the data for the output channel originates
from the microprocessor (Message Mode), then the
contents of the Connection Memory Low location
associated with the output channel are output
directly, and this data is output repetitively on the
channel once every frame until the microprocessor
intervenes.
The Connection Memory data is received, via the
Control Interface, at D7 to D0. The Control Interface
also receives address information at A5 to A0 and
handles the microprocessor control signals CS,
DTA, R/W and DS. There are two parts to any
address in the Data Memory or Connection Memory.
A5
A4
A3
A2
A1
A0
HEX ADDRESS
LOCATION
0
1
1
•
•
•
1
X
0
0
•
•
•
1
X
0
0
•
•
•
1
X
0
0
•
•
•
1
X
0
0
•
•
•
1
X
0
1
•
•
•
1
00 - 1F
20
21
•
•
•
3F
Control Register *
Channel 0†
Channel 1†
•
•
•
Channel 31†
* Writing to the Control Register is the only fast transaction.
† Memory and stream are specified by the contents of the Control Register.
Figure 3- Address Memory Map
2-6
MT8980D
The higher order bits come from the Control
Register, which may be written to or read from via
the Control Interface. The lower order bits come
from the address lines directly.
The Control Register also allows the chip to
broadcast messages on all ST-BUS outputs (i.e., to
put every channel into Message Mode), or to split the
memory so that reads are from the Data Memory
and writes are to the Connection Memory Low. The
Connection Memory High determines whether
individual output channels are in Message Mode,
and allows individual output channels to go into a
high-impedance state, which enables arrays of
MT8980s to be constructed. It also controls the
CSTo pin.
All ST-BUS timing is
signals C4i and F0i.
If address line A5 is low, then the Control Register is
addressed regardless of the other address lines (see
Fig. 3). If A5 is high, then the address lines A4-A0
select the memory location corresponding to channel
0-31 for the memory and stream selected in the
Control Register.
The data in the Control Register consists of mode
control bits, memory select bits, and stream address
bits (see Fig. 4). The memory select bits allow the
Connection Memory High or Low or the Data
Memory to be chosen, and the stream address bits
define one of the ST-BUS input or output streams.
Bit 7 of the Control Register allows split memory
operation - reads are from the Data Memory and
writes are to the Connection Memory Low.
derived from the two
Software Control
The address lines on the Control Interface give
access to the Control Register directly or, depending
on the contents of the Control Register, to the High
or Low sections of the Connection Memory or to the
Data Memory.
The other mode control bit, bit 6, puts every output
channel on every output stream into active Message
Mode; i.e., the contents of the Connection Memory
Low are output on the ST-BUS output streams once
every frame unless the ODE pin is low. In this mode
the chip behaves as if bits 2 and 0 of every
Connection Memory High location were 1,
regardless of the actual values.
(unused)
Mode
Control
Bits
7
6
Memory
Select
Bits
5
4
3
Stream
Address
Bits
2
1
0
BIT
NAME
DESCRIPTION
7
Split
Memory
When 1, all subsequent reads are from the Data Memory and writes are to the Connection
Memory Low, except when the Control Register is accessed again. When 0, the Memory
Select bits specify the memory for subsequent operations. In either case, the Stream
Address Bits select the subsection of the memory which is made available.
6
Message
Mode
When 1, the contents of the Connection Memory Low are output on the Serial Output
streams except when the ODE pin is low. When 0, the Connection Memory bits for each
channel determine what is output.
5
(unused)
4-3
2-0
Memory
0-0 - Not to be used
Select Bits 0-1 - Data Memory (read only from the microprocessor port)
1-0 - Connection Memory Low
1-1 - Connection Memory High
Stream
Address
Bits
The number expressed in binary notation on these bits refers to the input or output ST-BUS
stream which corresponds to the subsection of memory made accessible for subsequent
operations.
Figure 4 - Control Register Bits
2-7
MT8980D
No Corresponding Memory
- These bits give 0s if read.
7
6
5
4
Per Channel
Control Bits
3
2
1
0
BIT
NAME
DESCRIPTION
2
Message
Channel
When 1, the contents of the corresponding location in Connection Memory Low are
output on the location’s channel and stream. When 0, the contents of the corresponding
location in Connection Memory Low act as an address for the Data Memory and so
determine the source of the connection to the location’s channel and stream.
1
CSTo Bit
This bit is output on the CSTo pin one channel early. The CSTo bit for stream 0 is output
first.
0
Output
Enable
If the ODE pin is high and bit 6 of the Control Register is 0, then this bit enables the
output driver for the location’s channel and stream. This allows individual channels on
individual streams to be made high-impedance, allowing switching matrices to be
constructed. A 1 enables the driver and a 0 disables it.
Figure 5 - Connection Memory High Bits
Stream
Address
Bits
7
6
Channel
Address
Bits
5
4
3
2
1
0
BIT
NAME
DESCRIPTION
7-5*
Stream
Address
Bits*
The number expressed in binary notation on these 3 bits is the number of the ST-BUS
stream for the source of the connection. Bit 7 is the most significant bit. e.g., if bit 7 is 1,
bit 6 is 0 and bit 5 is 0, then the source of the connection is a channel on STi4.
4-0*
Channel
Address
Bits*
The number expressed in binary notation on these 5 bits is the number of the channel
which is the source of the connection (The ST-BUS stream where the channel lies is
defined by bits 7, 6 and 5.). Bit 4 is the most significant bit. e.g., if bit 4 is 1, bit 3 is 0, bit 2
is 0, bit 1 is 1 and bit 0 is 1, then the source of the connection is channel 19.
*If bit 2 of the corresponding Connection High location is 1 or if 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.
Figure 6 - Connection Memory Low Bits
2-8
MT8980D
If bit 6 of the Control Register is 0, then bits 2 and 0
of each Connection Memory High location function
normally (see Fig. 5). If bit 2 is 1, the associated STBUS output channel is in Message Mode; i.e., the
byte in the corresponding Connection Memory Low
location is transmitted on the stream at that channel.
Otherwise, one of the bytes received on the serial
inputs is transmitted and the contents of the
Connection Memory Low define the ST-BUS input
stream and channel where the byte is to be found
(see Fig. 6).
If the ODE pin is low, then all serial outputs are highimpedance. If it is high and bit 6 in the Control
Register is 1, then all outputs are active. If the ODE
pin is high and bit 6 in the Control Register is 0, then
the bit 0 in the Connection Memory High location
enables the output drivers for the corresponding
individual ST-BUS output stream and channel. Bit
0=1 enables the driver and bit 0=0 disables it (see
Fig. 5).
Bit 1 of each Connection Memory High location (see
Fig. 5) is output on the CSTo pin once every frame.
To allow for delay in any external control circuitry the
bit is output one channel before the corresponding
channel on the ST-BUS streams, and the bit for
stream 0 is output first in the channel; e.g., bit 1’s for
channel 9 of streams 0-7 are output synchronously
with ST-BUS channel 8 bits 7-0.
Applications
Use in a Simple Digital Switching System
Fig. 7 shows the interface between the MT8980s and
the filter/codecs. Fig. 8 shows the position of these
components in an example architecture.
The MT8964 filter/codec in Fig. 7 receives and
transmits digitized voice signals on the ST-BUS input
DR, and ST-BUS output DX, respectively. These
signals are routed to the ST-BUS inputs and outputs
on the top MT8980, which is used as a digital speech
switch.
The MT8964 is controlled by the ST-BUS input DC
originating from the bottom MT8980, which
generates the appropriate signals from an output
channel in Message Mode.
This architecture
optimizes the messaging capability of the line circuit
by building signalling logic, e.g., for on-off hook
detection, which communicates on an ST-BUS
output. This signalling ST-BUS output is monitored
by a microprocessor (not shown) through an ST-BUS
input on the bottom MT8980.
Fig. 8 shows how a simple digital switching system
may be designed using the ST-BUS architecture.
This is a private telephone network with 256
extensions which uses a single MT8980 as a speech
switch and a second MT8980 for communication with
the line interface circuits.
A larger digital switching system may be designed by
cascading a number of MT8980s. Fig. 9 shows how
four MT8980s may be arranged in a non-blocking
configuration which can switch any channel on any of
the ST-BUS inputs to any channel on the ST-BUS
outputs.
Figs. 7 and 8 show how MT8980s can be used with
MT8964s to form a simple digital switching system.
STo0
STi0
8980 used
as
speech
switch
MT8980
DX
DR
DC
STo0
STi0
8980 used
in message
mode for
control and
signalling
MT8964
Filter/Codec
Signalling
Logic
Line Driver
and
2- to 4Wire
Converter
Line Interface Circuit with 8964 Filter/Codec
MT8980
Figure 7 - Example of Typical Interface between 8980s and 8964s for Simple Digital Switching System
2-9
MT8980D
Line Interface Circuit
with Codec (e.g. 8964)
Line 1
8
Speech
Switch
8980
STi0-7
8
STo0-7
STo0-7
Controlling
MicroProcessor
8
STi0-7
•
•
•
Repeated for Lines
2 to 255
•
•
•
Repeated for Lines
2 to 255
8
Control &
Signalling
8980
Line Interface Circuit
with Codec (e.g.8964)
Line 256
Figure 8 - Example Architecture of a Simple Digital Switching System
Application Circuit with 6802 Processor
Fig. 10 shows an example of a complete circuit
which may be used to evaluate the chip.
For convenience, a 4 MHz crystal oscillator has been
used rather than a 4.096 MHz clock, as both are
within the limits of the chip’s specifications. The RC
delay used with the 393 counters ensures a
sufficient hold time for the FP signal, but the values
used may have to be changed if faster 393 counters
become available.
The chip is shown as memory mapped into the
MEK6802D3 system. Chip addresses 00-3F
correspond to processor addresses 2000-203F.
Delay through the address decoder requires the
VMA signal to be used twice to remove glitches. The
MEK6802D3 board uses a 10KΩ pullup on the MR
pin, which would have to be incorporated into the
circuit if the board was replaced by a processor.
8980
#1
IN 0/7
STi0/7 STo0/7
OUT 0/7
8980
#2
STi0/7 STo0/7
OUT 8/15
8980
#3
IN 8/15
STi0/7 STo0/7
8980
#4
STi0/7 STo0/7
Figure 9 - Four 8980s Arranged in a Non-Blocking 16 x 16 Configuration
2-10
MT8980D
A15
A14
A13
0V
0V
VMA
D7-D0
A15-A0
MEK6802D3
System
1
2
3
4
5
6
7
8
R/W
0V
MD
74
HCT
138
16
15
14
13
12
11
10
9
5V
16
15
14
13
12
11
10
9
5V
16
15
14
13
12
11
10
9
5V
16
15
14
13
12
11
10
9
5V
MR
VMA
1
2
3
4
5
6
7
8
A12
A11
A10
0V
0V
E
0V
909 Ω,
1/4W
5V
5V
DTA
STi0
STi1
STi2
STi3
STi4
STi5
STi6
STi7
VDD
F0i
C4i
A0
A1
A2
A3
A4
A5
DS
R/W
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
MT
8980
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
CSTo
ODE
STo0
STo1
STo2
STo3
STo4
STo5
STo6
STo7
VSS
D0
D1
D2
D3
D4
D5
D6
D7
CS
5V
A9
A8
A7
0V
0V
0V
1
2
3
4
5
6
7
8
0V
A6
VMA
0V
0V
0V
1
2
3
4
5
6
7
8
0V
C4i
0V
0V
1
2
3
4
5
6
7
SN
74
HCT
393
14
13
12
11
10
9
8
5V
0V
510 Ω
DTA
CS
0V
C4i
0V
F0i
0V
0V
0V
0V
1
2
3
4
5
6
7
SN
74
HCT
393
14
13
12
11
10
9
8
5V
MD
74
HCT
138
100pF
1
2 MD
3
74
4 HCT
5 240
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
MD
74
HCT
138
MD
74
HCT
138
5V
0V
MR
5V
4 MHz
2MΩ
Figure 10 - Application Circuit with 6802
2-11
MT8980D
Absolute Maximum Ratings*
Parameter
Symbol
Min
Max
Units
-0.3
7
V
1
VDD - VSS
2
Voltage on Digital Inputs
VI
VSS-0.3
VDD+0.3
V
3
Voltage on Digital Outputs
VO
VSS-0.3
VDD+0.3
V
4
Current at Digital Outputs
IO
40
mA
5
Storage Temperature
TS
+150
°C
6
Package Power Dissipation
PD
2
W
-65
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
.
Recommended Operating Conditions - Voltages are with respect to ground (VSS) unless otherwise stated.
Characteristics
Sym
Min
Typ‡
Max
Units
1
Operating Temperature
TOP
-40
+85
°C
2
Positive Supply
VDD
4.75
5.25
V
3
Input Voltage
VI
0
VDD
V
Test Conditions
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
DC Electrical Characteristics - Voltages are with respect to ground (VSS) unless otherwise stated.
Characteristics
1
2
3
4
5
I
N
P
U
T
S
6
7
8
9
10
11
O
U
T
P
U
T
S
Sym
Min
Typ‡
Supply Current
IDD
6
10
Input High Voltage
VIH
Input Low Voltage
VIL
0.8
V
Input Leakage
IIL
5
µA
Input Pin Capacitance
CI
2.0
VOH
2.4
Output High Current
IOH
10
Output Low Voltage
VOL
Output Low Current
IOL
High Impedance Leakage
IOZ
Output Pin Capacitance
CO
Outputs unloaded
V
8
Output High Voltage
mA
pF
V
15
mA
0.4
5
VI between VSS and VDD
10
5
8
V
IOH = 10 mA
Sourcing. VOH=2.4V
IOL = 5 mA
mA
Sinking. VOL = 0.4V
µA
VO between VSS and VDD
pF
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
VDD
Test Point
RL
Output
Pin
S1
S2
S1 is open circuit except
when testing output levels
or high impedance states.
S2 is switched to VDD or
VSS when testing output
levels or high impedance
states.
CL
VSS
VSS
Figure 11 - Output Test Load
2-12
MT8980D
AC Electrical Characteristics† - Clock Timing (Figures 12 and 13)
Sym
Min
Typ‡
Max
Units
Clock Period*
tCLK
220
244
300
ns
Clock Width High
tCH
95
122
150
ns
Clock Width Low
tCL
110
122
150
ns
Clock Transition Time
tCTT
Frame Pulse SetupTime
tFPS
20
200
ns
Frame Pulse Hold Time
tFPH
0.020
50
µs
Frame Pulse Width
tFPW
Characteristics
1
2
3
4
5
6
I
N
P
U
T
S
7
20
Test Conditions
ns
244
ns
† Timing is over recommended temperature & power supply voltages.
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
* Contents of Connection Memory are not lost if the clock stops, however, ST-BUS outputs go into the high impedance state.
NB: Frame Pulse is repeated every 512 cycles of C4i.
C4i
F0i
BIT
CELLS
Channel 31
Bit o
Channel 0
Bit 7
Figure 12 - Frame Alignment
tCLK
tCL
tCH
tCTT
2.0V
C4i
0.8V
tCHL
tFPH
tCTT
tFPH
tFPS
tFPS
2.0V
F0i
0.8V
tFPW
Figure 13 - Clock Timing
2-13
MT8980D
AC Electrical Characteristics† - Serial Streams (Figures 11, 14, 15 and 16)
1
2
3
4
5
6
O
U
T
P
U
T
S
7
8
9
I
N
Characteristics
Sym
Min
Typ‡
Max
Units
STo0/7 Delay - Active to High Z
tSAZ
20
50
80
ns
RL=1 KΩ*, CL=150 pF
STo0/7 Delay - High Z to Active
tSZA
25
60
125
ns
CL=150 pF
STo0/7 Delay - Active to Active
tSAA
30
65
125
ns
CL=150 pF
STo0/7 Hold Time
tSOH
25
45
ns
CL=150 pF
Output Driver Enable Delay
tOED
ns
RL=1 KΩ*, CL=150 pF
External Control Hold Time
tXCH
ns
CL=150 pF
External Control Delay
tXCD
75
110
ns
CL=150 pF
Serial Input Setup Time
tSIS
-40
-20
ns
Serial Input Hold Time
tSIH
45
0
125
50
90
Test Conditions
ns
† Timing is over recommended temperature & power supply voltages.
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
* High Impedance is measured by pulling to the appropriate rail with RL, with timing corrected to cancel time taken to discharge CL.
Bit Cell Boundary
2.0V
ODE
2.0V
0.8V
C4i
0.8V
tSOH
STo0 2.4V
to
STo7 0.4V
*
STo0 2.4V
to
STo7 0.4V
*
tOED
*
tOED
tSAZ
STo0 2.4V
to
STo7 0.4V
Figure 15 - Output Driver Enable
*
tSZA
tSOH
STo0 2.4V
to
STo7 0.4V
Bit Cell Boundaries
2.0V
C4i
0.8V
tSAA
tSIH
tXCH
2.4V
CSTo
STi0 2.0V
to
STi7 0.8V
0.4V
tSIS
tXCD
Figure 14 - Serial Outputs and External Control
2-14
Figure 16 - Serial Inputs
MT8980D
AC Electrical Characteristics† - Processor Bus (Figures 11 and 17)
Characteristics
Sym
Min
Typ‡
Max
Units
1
Chip Select Setup Time
tCSS
20
0
ns
2
Read/Write Setup Time
tRWS
25
5
ns
3
Address Setup Time
tADS
25
5
ns
4
Acknowledgement Delay Fast
tAKD
Slow
tAKD
2.7
20
5
Fast Write Data Setup Time
tFWS
6
Slow Write Data Delay
tSWD
7
Read Data Setup Time
tRDS
8
Data Hold Time
40
tDHT
20
Write
tDHT
20
100
ns
CL=150 pF
7.2
cycles
C4i cycles➀
ns
2.0
Read
Test Conditions
1.7
cycles
C4i cycles➀
0.5
cycles
C4i cycles➀, CL= 150 pF
ns
10
RL=1 KΩ∗, CL=150 pF
ns
9
Read Data To High Impedance
tRDZ
10
Chip Select Hold Time
tCSH
0
ns
11
Read/Write Hold Time
tRWH
0
ns
12
Address Hold Time
tADH
0
ns
13
Acknowledgement Hold Time
tAKH
10
50
90
60
80
ns
ns
RL=1 KΩ∗, CL=150 pF
RL=1 KΩ∗, CL=150 pF
† Timing is over recommended temperature & power supply voltages.
‡ Typical figures are at 25°C and are for design aid only: not guaranteed and not subject to production testing.
* High Impedance is measured by pulling to the appropriate rail with RL, with timing corrected to cancel time taken to discharge CL.
➀ Processor accesses are dependent on the C4i clock, and so some
timings are expressed as multiples of the C4i clock period.
2.0V
DS
0.8V
2.0V
CS
0.8V
tCSS
tCSH
tRWS
tRWH
2.0V
R/W
A5
to
A0
0.8V
2.0V
0.8V
tADS
tADH
tAKD
tAKH
2.4V
DTA
*
*
0.4V
tRDS
D7
to
D0
2.4V (Read) 2.0V (Write)
0.8V (Read 0.8V (Write)
tDHT
*
*
tSWD
tFWS
tRDZ
Figure 17 - Processor Bus
2-15
MT8980D
Notes:
2-16