ICM7216DIPI Intersil, ICM7216DIPI Datasheet - Page 13

• Manufacturer Part Number: ICM7216DIPI
• Description: IC COUNTER/TIMER FREQ 8DIG 28DIP
• Manufacturer: Intersil

Specifications of ICM7216DIPI

• Rohs Status: RoHS non-compliant
• Other names: 7216DIPI; NT5007

Test Circuit
Typical Applications
The lCM7216 has been designed for use in a wide range of
Universal and Frequency counters. In many cases, prescalers
will be required to reduce the input frequencies to under 10MHz.
Because INPUT A and INPUT B are digital inputs, additional
circuitry is often required for input buffering, amplification,
hysteresis, and level shifting to obtain a good digital signal.
The lCM7216B can be used as a minimum component
complete Universal Counter as shown in Figure 15. This
circuit can use input frequencies up to 10MHz at INPUT A
and 2MHz at INPUT B. If the signal at INPUT A has a very
low duty cycle it may be necessary to use a 74LS121
monostable multivibrator or similar circuit to stretch the input
pulse width to be able to guarantee that it is at least 50ns in
duration.
To measure frequencies up to 40MHz the circuit of
Figure 16 can be used. To obtain the correct measured
value, it is necessary to divide the oscillator frequency by
U.C.
O.F.
FR
TI.
P
F
6
FUNCTION
OVERFLOW
GENERATOR
GENERATOR
INDICATOR
FUNCTION
FUNCTION
D2
D5
D8
D4
D1
D3
LED
RESET
10K
INPUT B
DP
g
d
b
e
a
c
f
8
13
a
b
c
d
e
f
g
DP
D8
FIGURE 14. TEST CIRCUIT (ICM7216A SHOWN, OTHERS SIMILAR)
10
11
12
13
14
1
2
3
4
5
6
7
8
9
INPUT A
ICM7216A
D8
100pF
ICM7216B, ICM7216D
28
27
26
25
24
23
22
21
20
19
18
17
16
15
D7
V
DD
HOLD
D1
D2
D3
D4
D5
D6
D7
D8
D6
V
DD
10kΩ
four as well as the input frequency. In doing this the time
between measurements is also lengthened to 800ms and
the display multiplex rate is decreased to 125Hz.
If the input frequency is prescaled by ten, then the oscillator
can remain at 10MHz or 1MHz, but the decimal point must
be moved one digit to the right. Figure 17 shows a frequency
counter with a
is no external decimal point control with the lCM7216B, the
decimal point may be controlled externally with additional
drivers as shown in Figure 17. Alternatively, if separate
anodes are available for the decimal points, they can be
wired up to the adjacent digit anodes. Note that there can be
one zero to the left of the decimal point since the internal
leading zero blanking cannot be changed. In Figure 18
additional logic has been added to count the input directly in
period mode for maximum accuracy. In Figures 17 and 18,
INPUT A comes from Q C of the prescaler rather than Q D to
obtain an input duty cycle of 40%.
10kΩ
10kΩ
D5
22MΩ
V
DD
CRYSTAL
39pF
10MHz
D4
D1
D4
÷10
D2
D3
RANGE
V
DD
8
prescaler and an lCM7216A. Since there
39pF
DISPLAY
TYPICAL CRYSTAL SPECS:
F = 10MHz PARALLEL RESONANCE
C
R
.01/1
.1/10
1/100
10/1K
D3
TYP
BLANK
L
S
= 22pF
= <35Ω
D4
DISPLAY
D2
TEST 1MHz
D8
4
1N914s
D1
D2
OSC
EXT
INPUT
OSC
EXT
D1
TEST
8
D5