ICM7216B_04 Datasheet, PDF (8/18 Pages) Intersil Corporation – 8-Digit, Multi-Function, Frequency Counters/Timers

ICM7216B, ICM7216D
COUNTED
TRANSITIONS
INPUT A ^4.5V
0.5V
50ns MIN
50ns MIN
t_r = t_f = 10ns
FIGURE 6. WAVEFORM FOR GUARANTEED MINIMUM
f_A(MAX) FUNCTION = FREQUENCY,
FREQUENCY RATIO, UNIT COUNTER
9.
INPUT A OR ^4.5V
INPUT B _0.5V
MEASURED
INTERVAL
250ns
MIN
250ns
MIN
t_r = t_f = 10s
FIGURE 7. WAVEFORM FOR GUARANTEED MINIMUM
f_B(MAX) AND f_A(MAX) FOR FUNCTION = PERIOD
AND TIME INTERVAL
INTERNAL CONTROL
Function Input
The six functions that can be selected are: Frequency,
Period, Time Interval, Unit Counter, Frequency Ratio and
Oscillator Frequency. This input is available on the
lCM7216B only.
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 8. Table 2
shows which signals will be routed to each counter in
different cases. The output of the Main Counter is the
information which goes to the display. The Reference
Counter divides its input by 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 8 does not
show the complete functional diagram (See the Functional
Block Diagram). 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.
INTERNAL CONTROL
100Hz
INPUT A
INPUT B
INTERNAL OR
EXTERNAL
OSCILLATOR
INPUT A
INPUT
SELECTOR
INTERNAL CONTROL
INTERNAL CONTROL
CLOCK
REFERENCE COUNTER
÷1 ÷10 ÷100 ÷1000
RANGE SELECTOR
INPUT
SELECTOR
ENABLE
CLOCK
MAIN COUNTER
FIGURE 8. SIMPLIFIED BLOCK DIAGRAM OF FUNCTIONS IMPLEMENTATION
TABLE 2. 7216B INPUT ROUTING
FUNCTION
Frequency (f_A)
MAIN
COUNTER
Input A
REFERENCE COUNTER
100Hz (Oscillator ∏÷10⁵ or
10⁴)
Period (t_A)
Ratio (f_A/f_B)
Oscillator
Input A
Input A
Input B
8
TABLE 2. 7216B INPUT ROUTING
FUNCTION
MAIN
COUNTER
REFERENCE COUNTER
Time Interval
(A→B)
Oscillator
Input A
Input B
Unit Counter
(Count A)
Osc. Freq.
(f_OSC)
Input A
Oscillator
Not Applicable
100Hz (Oscillator ∏÷10⁵ or
10⁴)