SA8702
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SA8702
BLOCK MODE TIME SLOT ALLOCATION CIRCUIT
DESCRIPTION
The SA8702 (BMTSAC) is a Block Mode
Time Slot Allocation Circuit. The device is
used to generate 8 consecutive timeslots
in one of 4 blocks in a 32 time-slot PCM
system. Each timeslot pulse is 8 BLCK
cycles long. BCLK is the 2,048 station
clock provided by the system. An active
MRST will disable all outputs until a valid
XSYNC input is recognised. The output
TSX is delayed by half a cycle and indicates
that one of 8 timeslots is currently active.
There are 4 possible modes of operation,
selectable by means of the BL0 and BL1
pins (See Table 1).
APPLICATIONS
■
PCM Switching Systems
■
PCM Transmission Systems
■
Subscriber Multiplex Equipment
■
PBX Systems
PIN CONNECTIONS
All inputs and outputs are C-MOS
compatible. All outputs are push-pull with
the exception of TSX which is open drain.
The inputs MRST and BCLK are Schmitt
Trigger. Inputs BL0 and BL1 have pull-ups.
(See figure 1).
Figure 1.
SA8702
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02.02.93
1
SA8702
Operating Modes
BL1
BL0
0
0
1
1
0
1
0
1
Mode of Operation
Outputs
Outputs
Outputs
Outputs
active
active
active
active
in
in
in
in
timeslots 0 to 7
timeslots 8 to 15
timeslots 16 to 23
timeslots 24 to 31
Table 1.
Input pulse XSYNC occurs periodically in every frame and is used to generate the
first of the eight timeslots and also defines the beginning of Block 0. If XSYNC fails
high then the outputs will be generated as they were before the failure occured.
Should XSYNC fail low then the outputs will be deactivated after completion of the
frame.
Maximum Ratings
All voltages measured with respect to VSS.
Parameter
Symbol
Value
Units
Supply voltage
VDD
+7,5
V
Positive voltage on any pin
VHM
VDD +0,3
V
Negative voltage on any pin
VLM
VSS -0,3
V
Maximum current through any pin
IHM
±10
mA
Storage temperature
TST
-55 to +150
°C
Operating temperature
TO
-10 to +70
°C
Stresses beyond these values may cause permanent damage to the device. Exposure to
maximum rated conditions for extended periods may affect device reliability.
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SA8702
Operating Conditions:
All voltages measured with respect to VSS.
Inputs must never be left open.
DC Parameters
Symbol
Min.
Nom.
Max.
Supply Voltage
V DD
4,75
5,00
5,25
V
-
* Input Low Voltage
VIL
-
-
1,0
V
VDD
* Input High Voltage
** Output Low Voltage
VIH
VOL
4,0
-
-
0,5
V
V
** Output High Voltage
VOH
4,5
-
-
V
VDD = 5V
VDD = 5V
Iol
= 0,5mA
V DD = 5V
Ioh
= 0,5mA
4,75 ≤ VDD
≤ 5,25
-
Operating Frequency
-
Operating Temp. range
2,048 2,273
-10
25
70
Unit Conditions
MHz
°C
= 5V
* All inputs are C-MOS level compatible. Pins 6 and 7 have internal pull-up
devices.
** All outputs are push-pull except pin 1 which is open drain.
AC Parameters
XSYNC setup before
BCLK goes low
Output propagation
delay from active clock
edge
XSYNC hold time from
BCLK
Symbol
Min.
Nom.
Max.
Unit
Conditions
Ts
60
-
-
ns
T pd
-
-
150
ns
4,75 ≤ VDD
≤ 5,25
4,75 ≤ Vdd
≤ 5,25
Th
50
-
-
ns
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4,75 ≤ VDD
≤ 5,25
SA8702
PIN DESCRIPTION
Pin No.
I/O
Name
1
O
TSX
2
I
MRST
3
O
FSO
4
5
6
O
O
I
FS1
FS2
BL0
7
I
BL1
8
9
10
I
I
I
VSS
BCLK
XSYNC
11
12
13
14
15
16
O
O
O
O
O
I
FS7
FS6
FS5
FS4
FS3
VDD
Description
An open drain N-channel high impedance, but pulls
low during any active timeslot.
A Schmitt trigger input that asynchronously disables
all outputs.
A timeslot output which is normally low, and goes
active-high for 8 cycles of BCLK when a valid XSYNC
is made.
Similar to pin 3.
Similar to pin 3.
The input for the LSB of the 2 bit word which defines
the active block.
The input for the MSB of the 2 bit word which defines
the active block.
The OV ground connection to the device.
The 2,048MHz station clock input.
The input pulse XSYNC used to generate the first of
the eight timeslots and also defines the beginning of
block 0.
Similar to pin 3.
Similar to pin 3.
Similar to pin 3.
Similar to pin 3.
Similar to pin 3.
The positive supply to the device.
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SA8702
TIMING DIAGRAM
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SA8702
Disclaimer:
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without the express written consent of SAMES. The information contained herein is current as of the date of
publication; however, delivery of this document shall not under any circumstances create any implication that the
information contained herein is correct as of any time subsequent to such date. SAMES does not undertake to
inform any recipient of this document of any changes in the information contained herein, and SAMES expressly
reserves the right to make changes in such information, without notification,even if such changes would render
information contained herein inaccurate or incomplete. SAMES makes no representation or warranty that any
circuit designed by reference to the information contained herein, will function without errors and as intended by
the designer.
Any sales or technical questions may be posted to our e-mail adress below:
[email protected]
For the latest updates on datasheets, please visit our web site:
http://www.sames.co.za
South African Micro-Electronic Systems (Pty) Ltd
P O Box 15888,
33 Eland Street,
Lynn East,
Koedoespoort Industrial Area,
0039
Pretoria,
Republic of South Africa,
Republic of South Africa
Tel:
Fax:
012 333-6021
012 333-8071
Tel:
Fax:
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6
Int +27 12 333-6021
Int +27 12 333-8071