ICM7226 Intersil Corporation, ICM7226 Datasheet - Page 8

• Manufacturer Part Number: ICM7226
• Description: 8-Digit Multi-Function Frequency Counter/Timer
• Manufacturer: Intersil Corporation

Table 1 shows the functions selected by each digit for these
inputs.
Function Input
The six functions that can be selected are: Frequency,
Period, Time Interval, Unit Counter, Frequency Ratio and
Oscillator Frequency.
FUNCTION INPUT
Pin 4
RANGE INPUT
Pin 21
CONTROL INPUT
Pin 1
External DP INPUT
Pin 20
INPUT
TABLE 1. MULTIPLEXED INPUT FUNCTIONS
INTERNAL OR
OSCILLATOR
EXTERNAL
INPUT A
INPUT B
INPUT A
100Hz
FIGURE 11. SIMPLIFIED BLOCK DIAGRAM OF FUNCTIONS IMPLEMENTATION
Frequency
Period
Frequency Ratio
Time Interval
Unit Counter
Oscillator Frequency
0.01s/1 Cycle
0.1s/10 Cycles
1s/100 Cycles
10s/1K Cycles
Enable External Range Input
Display Off
Display Test
1MHz Select
External Oscillator Enable
External Decimal Point
Enable
Decimal point is output for same digit
that is connected to this input.
FUNCTION
INTERNAL CONTROL
INTERNAL CONTROL
SELECTOR
SELECTOR
INPUT
INPUT
ICM7226A, ICM7226B
D4 and
DIGIT
Hold
D1
D8
D2
D5
D4
D3
D1
D2
D3
D4
D5
D8
D2
D1
D3
INTERNAL CONTROL
9-22
The implementation of different functions is done by routing
the different signals to two counters, called “Main Counter”
and “Reference Counter”. A simplified block diagram of the
device for functions realization is shown in Figure 11. Table 2
shows which signals will be routed to each counter in differ-
ent cases. The output of the Main Counter is the information
which goes to the display. The Reference Counter divides its
input to 1, 10, 100 and 1000. One of these outputs will be
selected through the range selector and drive the enable
input of the Main Counter. This means that the Reference
Counter, along with its' associated blocks, directs the Main
Counter to begin counting and determines the length of the
counting period. Note that Figure 11 does not show the com-
plete functional diagram (See the Functional Block Dia-
gram). After the end of each counting period, the output of
the Main Counter will be latched and displayed, then the
counter will be reset and a new measurement cycle will
begin. Any change in the FUNCTION INPUT will stop the
present measurement without updating the display and then
initiate a new measurement. This prevents an erroneous first
reading after the FUNCTION INPUT is changed. In all
cases, the 1-0 transitions are counted or timed.
Frequency (f
Period (t
Ratio (f
Time Interval
(A B)
Unit Counter
(Count A)
Osc. Freq.
(f
OSC
FUNCTION
)
A
A
/f
)
B
)
A
)
TABLE 2. INPUT ROUTING
Input A
Oscillator
Input A
Oscillator
Input A
Oscillator
CLOCK
ENABLE
CLOCK
COUNTER
REFERENCE COUNTER
INTERNAL CONTROL
MAIN
RANGE SELECTOR
1
MAIN COUNTER
10
100Hz (Oscillator
Input A
Input B
Input A
Input B
Not Applicable
100Hz (Oscillator
100
COUNTER
1000
10
10
5
5
or 10
or 10
4
4
)
)