LS7212 LSI Computer Systems, LS7212 Datasheet - Page 8

• Manufacturer Part Number: LS7212
• Description: PROGRAMMABLE DIGITAL DELAY TIMER
• Manufacturer: LSI Computer Systems

ƒo
Case 1, Mode = DO;
ƒo
Case 2, Mode = DD;
EXAMPLES OF CASE 1 and CASE 2 FREQUENCY DIVISIONS WITH W = 2
CASE 1. MODE = DO or DR; PRESCALE FACTOR, S = 1
CASE 2. MODE = DD; PRESCALE FACTOR, S = 1
ƒi
The ƒo pulse width is non-symmetrical (non-50% duty -cycle)
The ƒo pulse widths are symmetrical with 50% duty -cycle
In this setup a frequency division of the input clock, ƒi by a factor of 2 to 257, in increments of 1 can be
obtained according to the equation:
In this setup a frequency division of the input clock, ƒi by a factor of 2 to 512, in increments of 2 can be
obtained according to the equation:
ƒi
ƒo
+V
÷
÷
6
4
FIGURE 10. PROGRAMMABLE FREQUENCY DIVIDER
ƒo =
ƒo =
W + 2
18
2(W + 1)
ƒi
1
2
4
9
7
ƒi
A
B
RESET
OUT
CLOCK
TRIG
where W (weighting factor) = 0 to 255
where W (weighting factor) = 0 to 255
L S 7 2 1 2
3
V
+V
Vss
DD
8
WB0
WB1
WB2
WB3
WB4
WB5
WB6
WB7
17
16
15
14
13
12
11
10