SY10E136 Micrel Semiconductor, SY10E136 Datasheet - Page 5

• Manufacturer Part Number: SY10E136
• Description: 6-BIT UNIVERSAL UP/DOWN COUNTER
• Manufacturer: Micrel Semiconductor

Micrel
Overview
cascadable universal counters. Using the S
pins, the user can select between preset, count up, count
down and hold count. The Master Reset pin will reset the
internal counter and set the C
flops.
outputs will go to a high state during the preset operation.
In addition, since the carry-out outputs are registered, they
will not go low if terminal count is loaded into the register.
The look-ahead-carry-out output functions similarly.
from the least significant bits for control of the two carry-out
functions. This architecture not only reduces the carry-out
delay, but is essential to incorporate the registered carry-
out functions. In addition to being faster, the resulting carry-
out signals are stable and glitch free because these functions
are registered.
Cascading Multiple E136 Devices
the 6 bits available with the E136. For these applications,
several E136 devices can be cascaded to increase the bit
width of the counter to meet the needs of the application.
necessarily impacted the maximum count frequency of the
resulting counter chain. This performance impact was the
result of the terminal count signal of the lower order counters
LOGIC DIAGRAM
APPLICATIONS INFORMATION
The SY10E/100E136 are 6-bit synchronous, presettable,
Note from the schematic the use of the master information
Many applications require counters significantly larger than
In the past, cascading several 136-type universal counters
CL
CLOCK
C
CLK
OUT
Unlike previous 136-type counters, the carry-out
OUT
"LO"
"LO"
C
111101
CL
CLK
IN
IN
Q
D
0
LSB
0
– Q
– D
CL
OUT
C
5
5
OUT
OUT
, CL
"LO"
OUT
111110
Figure 1. 24-bit Cascaded E136 Counter
1
and CL
and S
C
CL
CLK
IN
2
IN
control
Q
D
IN
0
0
flip-
– Q
– D
CL
C
5
5
OUT
OUT
5
111111
having to ripple through the entire counter chain. As a
result, past counters of this type were not widely used in
large bit counter applications.
binary counter was implemented to alleviate the need to
ripple propagate the terminal count signal. Unfortunately,
these types of counters require external gating for cascading
designs of more than two devices. In addition to requiring
additional components, these external gates limit the
cascaded count frequency to a value less than the free
running count frequency of a single counter. Although there
is a performance impact with this type of architecture, it is
minor compared to the impact of the ripple propagate
designs. As a result, the E016-type counters have been
used extensively in applications requiring very high speed,
wide bit width synchronous counters.
universal counter designs in the E136 universal counter.
These enhancements make the E136 the unparalleled leader
in its class. With the addition of look-ahead-carry features
on the terminal count signal, very large counter chains can
be designed which function at very nearly the same clock
frequency as a single free running device. More importantly,
these counter chains require no external gating. Figure 1
below illustrates the interconnect scheme for using the look-
ahead-carry features of the E136 counter.
An alternative counter architecture similar to the E016
Several improvements have been incorporated to past
C
CL
CLK
IN
IN
Q
D
0
0
000000
– Q
– D
CL
C
5
5
OUT
OUT
000001
C
CL
CLK
IN
IN
Q
D
MSB
0
0
– Q
– D
CL
SY100E136
C
SY10E136
5
5
OUT
OUT