CMOS
Pin Description (continued)
Pin #
Name
DIP
PLCC
MT8941
Description
Clock 4.096 MHz- Bidirectional (TTL compatible input and Totem-pole output)
- When
the mode select bit MS3 (pin 17) is HIGH, it provides the 4.096 MHz clock output with the
falling edge in the frame pulse (F0b) window. When pin 17 is LOW, C4b is an input to an
external clock at 4.096 MHz.
Clock 2.048 MHz (Three state output)
- This is the divide by two output of C4b (pin 13) and
has a falling edge in the frame pulse (F0b) window. The high impedance state of this output
is controlled by EN
C2o
(pin 16).
Clock 2.048 MHz (Three state output) -
This is the divide by two output of C4b (pin 13) and
has a rising edge in the frame pulse (F0b) window. The high impedance state of this output is
controlled by EN
C2o
(pin 16).
13
15
C4b
14
16
C2o
15
17
C2o
16
19
EN
C2o
Enable 2.048 MHz clock (TTL compatible input) -
This active high input enables both C2o
and C2o outputs (pins 14 and 15). When LOW, these outputs are in high impedance
condition.
MS3
Ai, Bi
Y
o
CVb
Mode select 3 input (TTL compatible) -
This input in conjunction with MS2 (pin 7) selects
the minor mode of operation for DPLL #2. (Refer to Table 3.)
Inputs A and B (TTL compatible) -These
are the two inputs of the uncommitted NAND
gate
.
Output Y (Totem pole output) -
Output of the uncommitted NAND gate.
Variable clock Bidirectional (TTL compatible input and Totem-pole output) -
When
acting as an output (MS1-LOW) during the NORMAL mode of DPLL #1, this pin provides the
1.544 MHz clock locked to the input frame pulse F0i (pin 5). When MS1 is HIGH, it is an
input to an external clock at 1.544 MHz or 2.048 MHz to provide the internal signal at 8 kHz
to DPLL #2.
Variable clock (Three state output) -
This is the inverse output of the signal appearing on
pin 21, the high impedance state of which is controlled by EN
CV
(pin 1).
Reset (Schmitt trigger input)
- This input (active LOW) puts the MT8941 in its reset state.
To guarantee proper operation, the device must be reset after power-up. The time constant
for a power-up reset circuit (see Figures 9-13) must be a minimum of five times the rise time
of the power supply. In normal operation, the RST pin must be held low for a minimum of
60nsec to reset the device.
V
DD
(+5V)
Power supply.
No Connection.
17
18,
19
20
21
20
21,
22
23
24
22
23
26
27
CV
RST
24
28
4,
5,
18,
25
V
DD
NC
3-45
MITEL [ MITEL NETWORKS CORPORATION ]
