7

SY10E016

SY100E016

Micrel, Inc.

M9999-032006

hbwhelp@micrel.com or (408) 955-1690

Programmable Divider

The E016 has been designed with a control pin which

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 2

below illustrates the input conditions necessary for utilizing

the E016 as a programmable divider set up to divide by 113.

To determine what value to load into the device to accomplish

the desired division, the designer simply subtracts the binary

equivalent of the desired divide ratio for the binary value for

256. As an example for a divide ration of 113:

where

Forcing this input condition, as per the set-up in Figure 2, will

result in the waveforms of Figure 3. Note that the TC output

HLL

H

H

LH

H

PE

CE

TCLD

CLK

TC

H

L

H

Figure 2. Mod 2 to 256 Programmable Divider

Figure 3. Divide by 113 E016 Programmable Divider Waveforms

CLOCK

PE

TC

LOAD

1001 0000

1001 0001

1111 1100

1111 1101

1111 1110

1111 1111

LOAD

Divide by 113