MC10E016 ON Semiconductor, MC10E016 Datasheet - Page 8

• Manufacturer Part Number: MC10E016
• Description: 8-BIT SYNCHRONOUS BINARY UP COUNTER
• Manufacturer: ON Semiconductor

Programmable Divider
makes it ideal for use as an 8−bit programmable divider. The
TCLD pin (load on terminal count) when asserted reloads
the data present at the parallel input pin (Pn’s) upon reaching
terminal count (an all 1s state on the outputs). Because this
feedback is built internal to the chip, the programmable
division operation will run at very nearly the same frequency
as the maximum counting frequency of the device. Figure 4
below illustrates the input conditions necessary for utilizing
the E016 as a programmable divider set up to divide by 113.
accomplish the desired division, the designer simply
subtracts the binary equivalent of the desired divide ratio
from the binary value for 256. As an example for a divide
ratio of 113:
Pn’s = 256 − 113 = 8F
where:
P0 = LSB and P7 = MSB
will result in the waveforms of Figure 5. Note that the TC
output is used as the divide output and the pulse duration is
Clock
The E016 has been designed with a control pin which
To determine what value to load into the device to
Forcing this input condition as per the setup in Figure 4
PE
TC
H
H
L
Figure 4. Mod 2 to 256 Programmable Divider
PE
CE
TCLD
CLK
P7
Q7
H
Q6
P6
L
16
Q5
P5
L
= 1000 1111
Load
P4
Q4
L
Figure 5. Divide by 113 E016 Programmable Divider Waveforms
Q3
P3
H
1001 0000
Q2
P2
APPLICATIONS INFORMATION (continued)
H
Q1
P1
H
Q0
P0
H
1001 0001
TC
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•••
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DIVIDE BY 113
1111 1100
8
equal to a full clock period. For even divide ratios, twice the
desired divide ratio can be loaded into the E016 and the TC
output can feed the clock input of a toggle flip flop to create
a signal divided as desired with a 50% duty cycle.
to 256 inclusive. If divide ratios of greater than 256 are
needed multiple E016s can be cascaded in a manner similar
to that already discussed. When E016s are cascaded to build
larger dividers the TCLD pin will no longer provide a means
for loading on terminal count. Because one does not want to
reload the counters until all of the devices in the chain have
reached terminal count, external gating of the TC pins must
be used for multiple E016 divider chains.
Table 11. Preset Values for Various Divide Ratios
Divide
A single E016 can be used to divide by any ratio from 2
Ratio
112
113
114
254
255
256
w
w
2
3
4
5
•
•
1111 1101
P7
H
H
H
H
w
H
H
H
•
•
•
L
L
L
P6
H
H
H
H
•
•
L
L
L
•
•
L
L
L
1111 1110
P5
H
H
H
H
L
L
L
L
L
L
•
•
•
•
Preset Data Inputs
P4
H
H
H
H
H
•
•
L
L
•
•
L
L
L
1111 1111
P3
H
H
H
H
H
H
L
L
L
L
•
•
•
•
P2
H
H
H
H
H
L
L
L
L
L
•
•
•
•
Load
P1
H
H
H
H
H
L
L
L
L
L
•
•
•
•
P0
H
H
H
H
L
L
L
L
L
L
•
•
•
•