9-10

Features All Versions

· Functions as a Frequency Counter (DC to 10MHz)

· Four Internal Gate Times: 0.01s, 0.1s, 1s, 10s in

Frequency Counter Mode

· Directly Drives Digits and Segments of Large Multi-

plexed LED Displays (Common Anode and Common
Cathode Versions)

· Single Nominal 5V Supply Required

· Highly Stable Oscillator, Uses 1MHz or 10MHz Crystal

· Internally Generated Decimal Points, Interdigit Blanking,

Leading Zero Blanking and Overflow Indication

· Display Off Mode Turns Off Display and Puts Chip Into

Low Power Mode

· Hold and Reset Inputs for Additional Flexibility

Features ICM7216A and ICM7216B

· Functions Also as a Period Counter, Unit Counter,

Frequency Ratio Counter or Time Interval Counter

· 1 Cycle, 10 Cycles, 100 Cycles, 1000 Cycles in Period,

Frequency Ratio and Time Interval Modes

· Measures Period From 0.5

s to 10s

Features ICM7216D

· Decimal Point and Leading Zero Banking May Be

Externally Selected.

Description

The ICM7216A and ICM7216B are fully integrated Timer
Counters with LED display drivers. They combine a high
frequency oscillator, a decade timebase counter, an
8-decade data counter and latches, a 7-segment decoder,
digit multiplexers and 8-segment and 8-digit drivers which
directly drive large multiplexed LED displays. The counter
inputs have a maximum frequency of 10MHz in frequency
and unit counter modes and 2MHz in the other modes. Both
inputs are digital inputs. In many applications, amplification
and level shifting will be required to obtain proper digital
signals for these inputs.

The ICM7216A and ICM7216B can function as a frequency
counter, period counter, frequency ratio (f

) counter, time

interval counter or as a totalizing counter. The counter uses
either a 10MHz or 1MHz quartz crystal timebase. For period
and time interval, the 10MHz timebase gives a 0.1

resolution. In period average and time interval average, the
resolution can be in the nanosecond range. In the frequency
mode, the user can select accumulation times of 0.01s, 0.1s,
1s and 10s. With a 10s accumulation time, the frequency
can be displayed to a resolution of 0.1Hz in the least
significant digit. There is 0.2s between measurements in all
ranges.

The ICM7216D functions as a frequency counter only, as
described above.

All versions of the ICM7216 incorporate leading zero
blanking. Frequency is displayed in kHz. In the ICM7216A
and ICM7216B, time is displayed in

s. The display is

multiplexed at 500Hz with a 12.2% duty cycle for each digit.
The ICM7216A is designed for common anode displays with
typical peak segment currents of 25mA. The ICM7216B and
ICM7216D are designed for common cathode displays with
typical peak segment currents of 12mA. In the display off
mode, both digit and segment drivers are turned off,
enabling the display to be used for other functions.

Ordering Information

PART NUMBER

TEMP.

RANGE (

PACKAGE

PKG.

NO.

ICM7216AlJl

-25 to 85

28 Ld CERDIP

F28.6

ICM7216BlPl

-25 to 85

28 Ld PDIP

E28.6

ICM7216DlPl

-25 to 85

28 Ld PDIP

E28.6

August 1997

ICM7216A, ICM7216B,

ICM7216D

8-Digit, Multi-Function,

Frequency Counters/Timers

File Number

3166.1

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

http://www.intersil.com or 407-727-9207

Intersil Corporation 1999

9-11

Pinouts

ICM7216A

COMMON ANODE

(CERDIP)

TOP VIEW

ICM7216B

COMMON CATHODE

(PDIP)

TOP VIEW

ICM7216D

COMMON CATHODE

(PDIP)

TOP VIEW

CONTROL INPUT

INPUT B

FUNCTION INPUT

DECIMAL POINT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

RESET INPUT

RANGE INPUT

INPUT A

OSC OUTPUT

OSC INPUT

EXT OSC INPUT

DIGIT 1 OUTPUT

DIGIT 3 OUTPUT

DIGIT 5 OUTPUT

DIGIT 6 OUTPUT

DIGIT 7 OUTPUT

DIGIT 8 OUTPUT

HOLD INPUT

DIGIT 2 OUTPUT

DIGIT 4 OUTPUT

OUTPUT

CONTROL INPUT

INPUT B

FUNCTION INPUT

DIGIT 1 OUTPUT

DIGIT 3 OUTPUT

DIGIT 2 OUTPUT

DIGIT 4 OUTPUT

DIGIT 5 OUTPUT

DIGIT 6 OUTPUT

DIGIT 7 OUTPUT

DIGIT 8 OUTPUT

RESET INPUT

RANGE INPUT

INPUT A

OSC OUTPUT

OSC INPUT

EXT OSC INPUT
DECIMAL POINT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

HOLD INPUT

SEG

OUTPUT

SEG

OUTPUT

CONTROL INPUT

MEASUREMENT IN PROGRESS

DIGIT 1 OUTPUT

DIGIT 3 OUTPUT

DIGIT 2 OUTPUT

DIGIT 4 OUTPUT

DIGIT 5 OUTPUT

DIGIT 6 OUTPUT

DIGIT 7 OUTPUT

DIGIT 8 OUTPUT

RESET INPUT

EX. DECIMAL POINT INPUT

RANGE INPUT

INPUT A

OSC OUTPUT

OSC INPUT

EXT OSC INPUT

DECIMAL POINT OUTPUT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

SEG

OUTPUT

HOLD INPUT

SEG

OUTPUT

SEG

OUTPUT

ICM7216A, ICM7216B, ICM7216D

9-12

Functional Block Diagram

NOTES:

1. Function input and input B available on ICM7216A/B only.

2. Ext DP input and MEASUREMENT IN PROGRESS output available on ICM7216D only.

STORE AND

RESET LOGIC

REFERENCE

RANGE SELECT

DIGIT

DECODER

OSC

RANGE

CONTROL

DECODER

SEGMENT

INPUT

MAIN

DRIVERS

COUNTER

LOGIC

CONTROL

LOGIC

CONTROL

LOGIC

CONTROL

LOGIC

DATA LATCHES AND

OUTPUT MUX

MAIN

COUNTER

SELECT

CONTROL

LOGIC

DRIVER

LOGIC

EXT

OSC

INPUT

OSC

INPUT

OSC

OUTPUT

RESET

INPUT

INPUT A

FUNCTION

INPUT

(NOTE 1)

OVERFLOW

STORE

100Hz

HOLD

INPUT

INPUT B

(NOTE 1)

MEASUREMENT
IN PROGRESS
OUTPUT
(NOTE 2)

SEGMENT
OUTPUTS

EXT
DP
INPUT
(NOTE 2)

CONTROL
INPUT

RANGE
INPUT

DIGIT
OUTPUTS
(8)

(8)

ICM7216A, ICM7216B, ICM7216D

9-13

Absolute Maximum Ratings

Thermal Information

Maximum Supply Voltage (V

- V

). . . . . . . . . . . . . . . . . . . . 6.5V

Maximum Digit Output Current . . . . . . . . . . . . . . . . . . . . . . . . 400mA
Maximum Segment Output Current . . . . . . . . . . . . . . . . . . . . . 60mA
Voltage On Any Input or
Output Terminal (Note 1) . . . . . . . . . . . .(V

+0.3V) to (V

-0.3V)

Operating Conditions

Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . -25

C to 85

Thermal Resistance (Typical, Note 2)

(

C/W)

(

C/W)

CERDIP Package . . . . . . . . . . . . . . . .

PDIP Package . . . . . . . . . . . . . . . . . . .

N/A

Maximum Junction Temperature

CERDIP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

PDIP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

Maximum Storage Temperature Range . . . . . . . . . .-65

C to 150

Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300

CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation
of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.

NOTES:

1. The ICM7216 may be triggered into a destructive latchup mode if either input signals are applied before the power supply is applied or if

input or outputs are forced to voltages exceeding V

to V

by more than 0.3V.

is measured with the component mounted on an evaluation PC board in free air.

Electrical Specifications

= 5.0V, V

= 0V, T

= 25

C, Unless Otherwise Specified

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

ICM7216A/B

Operating Supply Current, I

Display Off, Unused Inputs to V

Supply Voltage Range (V

-V

), V

SUPPLY

INPUT A, INPUT B Frequency at f

MAX

4.75

6.0

Maximum Frequency INPUT A, Pin 28, f

A(MAX)

Figure 9, Function = Frequency, Ratio,
Unit Counter

MHz

Function = Period, Time Interval

2.5

MHz

Maximum Frequency INPUT B, Pin 2, f

B(MAX)

Figure 10

2.5

MHz

Minimum Separation INPUT A to INPUT B Time
Interval Function

Figure 1

250

Maximum Oscillator Frequency and External Oscillator
Frequency, f

OSC

MHz

Minimum External Oscillator Frequency, f

OSC

100

kHz

Oscillator Transconductance, g

= 4.75V, T

= 85

2000

Multiplex Frequency, f

MUX

OSC

= 10MHz

500

Time Between Measurements

OSC

= 10MHz

200

Input Voltages: Pins 2, 13, 25, 27, 28

Input Low Voltage, V

INL

1.0

Input High Voltage, V

lNH

3.5

Input Resistance to V

Pins 13, 24, R

= V

-1.0V

100

400

Input Leakage Pins 27, 28, 2, I

ILK

Input Range of Change, dV

/dt

Supplies Well Bypassed

mV/

ICM7216A

Digit Driver: Pins 15, 16, 17, 19, 20, 21, 22, 23

High Output Current, I

OUT

= V

-2.0V

-140

-180

Low Output Current, I

OUT

= V

+1.0V

0.3

Segment Driver: Pins 4, 5, 6, 7, 9,10, 11, 12

Low Output Current, I

OUT

= V

+1.5V

High Output Current, I

OUT

= V

-2.5V

-100

Multiplex Inputs: Pins 1, 3, 14

Input Low Voltage, V

INL

0.8

Input High Voltage, V

INH

2.0

Input Resistance to V

, R

= V

+1.0V

100

ICM7216A, ICM7216B, ICM7216D

9-14

ICM7216B

Digit Driver: Pins 4, 5, 6, 7, 9, 10, 11, 12

Low Output Current, I

OUT

= V

+1.3V

High Output Current, I

OUT

= V

-2.5V

-100

Segment Driver: Pins 15, 16, 17, 19, 20, 21, 22, 23

High Output Current, I

OUT

= V

-2.0V

-10

Leakage Current, I

SLK

OUT

= V

-2.5V

Multiplex Inputs: Pins 1, 3, 14

Input Low Voltage, V

INL

-2.0

Input High Voltage, V

lNH

-0.8

Input Resistance to V

, R

= V

-2.5V

100

360

ICM7216D

Operating Supply Current, I

Display Off, Unused Inputs to V

Supply Voltage Range (V

-V

), V

SUPPLY

INPUT A Frequency at f

MAX

4.75

6.0

Maximum Frequency INPUT A, Pin 28, f

A(MAX)

Figure 9

MHz

Maximum Oscillator Frequency and External Oscillator
Frequency, f

OSC

MHz

Minimum External Oscillator Frequency, f

OSC

100

kHz

Oscillator Transconductance, g

= 4.75V, T

= 85

2000

Multiplex Frequency, f

MUX

OSC

= 10MHz

500

Time Between Measurements

OSC

= 10MHz

200

Input Voltages: Pins 12, 27, 28

Input Low Voltage, V

INL

1.0

Input High Voltage, V

INH

3.5

Input Resistance to V

DD,

Pins 12, 24, R

= V

-1.0V

100

400

Input Leakage, Pins 27, 28, I

ILK

Output Current, Pin 2, I

= +0.4V

0.36

Output Current, Pin 2, I

= V

-0.8V

265

Input Rate of Change, dV

/dt

Supplies Well Bypassed

mV/

Digit Driver: Pins 3, 4, 5, 6, 8, 9, 10, 11

Low Output Current, I

OUT

= +1.3V

High Output Current, I

OUT

= V

-2.5V

100

Segment Driver: Pins 15, 16, 17, 19, 20, 21, 22, 23

High Output Current, I

OUT

= V

-2.0V

Leakage Current, I

SLK

OUT

= V

-2.5V

Multiplex Inputs: Pins 1, 13, 14

Input Low Voltage, V

lNL

-2.0

Input High Voltage, V

INH

-0.8

Input Resistance to V

, R

= V

-1.0V

100

360

Electrical Specifications

= 5.0V, V

= 0V, T

= 25

C, Unless Otherwise Specified (Continued)

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

ICM7216A, ICM7216B, ICM7216D

9-15

Timing Diagram

Typical Performance Curves

FIGURE 2. f

(MAX), f

(MAX) AS A FUNCTION OF SUPPLY

FIGURE 3. ICM7216A TYPICAL I

DIG

vs V

-V

OUT

MEASUREMENT

IN PROGRESS

(INTERNAL ON

7216A/B)

30ms TO 40ms

INTERNAL

STORE

INTERNAL

RESET

INPUT A

INPUT B

PRIMING EDGES

PRIMING

FUNCTION:
TIME INTERVAL

UPDATE

190ms TO 200ms

40ms

60ms

40ms

MEASUREMENT INTERVAL

250ns MIN

MEASURED

INTERVAL

(FIRST)

MEASURED

INTERVAL

(LAST)

UPDATE

NOTE:

1. If range is set to 1 event, first and last measured interval will coincide.

FIGURE 1. WAVEFORMS FOR TIME INTERVAL MEASUREMENT (OTHERS ARE SIMILAR, BUT WITHOUT PRIMING PHASE)

(MAX) FREQUENCY UNIT COUNTER,

FREQUENCY RATIO MODES

(MAX) f

(MAX) PERIOD,

TIME INTERVAL MODES

= 25

-V

(V)

FREQ

UENCY (MHz)

-20

4.5

6.0V

300

200

100

-V

OUT

(V)

DIG

(mA)

ICM7216A, ICM7216B, ICM7216D

9-16

FIGURE 4. ICM7216B AND ICM7216D TYPICAL I

SEG

vs V

-V

OUT

FIGURE 5. ICM7216A TYPICAL I

SEG

vs V

OUT

FIGURE 6. ICM7216B AND ICM7216D TYPICAL I

DIGIT

vs V

OUT

FIGURE 7. ICM7216A TYPICAL I

SEG

vs V

OUT

FIGURE 8. ICM7216B AND ICM7216D TYPICAL I

DIGIT

vs V

OUT

Typical Performance Curves

(Continued)

-20

4.5

-V

OUT

(V)

SEG

(mA)

= 5.5V

OUT

(V)

SEG

(mA)

= 25

= 4.5V

= 5V

-20

= 5V

200

150

100

OUT

(V)

DIGIT

(mA)

-20

= 5V

OUT

(V)

SEG

(mA)

= 5.5V

200

100

OUT

(V)

DIGIT

(mA)

= 25

= 4.5V

= 5V

ICM7216A, ICM7216B, ICM7216D

9-17

Description

INPUTS A and B

INPUTS A and B are digital inputs with a typical switching
threshold of 2V at V

= 5V. For optimum performance the

peak-to-peak input signal should be at least 50% of the
supply voltage and centered about the switching voltage.
When these inputs are being driven from TTL logic, it is
desirable to use a pullup resistor. The circuit counts high to
low transitions at both inputs. (INPUT B is available only on
lCM7216A and lCM7216B).

Note that the amplitude of the input should not exceed the
device supply (above the V

and below the V

) by more

than 0.3V, otherwise the device may be damaged.

Multiplexed Inputs

The FUNCTION, RANGE, CONTROL and EXTERNAL
DECIMAL POINT inputs are time multiplexed to select the
function desired. This is achieved by connecting the appro-
priate Digit driver output to the inputs. The function, range
and control inputs must be stable during the last half of each
digit output, (typically 125

s). The multiplexed inputs are

active high for the common anode lCM7216A and active low
for the common cathode lCM7216B and lCM7216D.

Noise on the multiplex inputs can cause improper operation.
This is particularly true when the unit counter mode of
operation is selected, since changes in voltage on the digit
drivers can be capacitively coupled through the LED diodes
to the multiplex inputs. For maximum noise immunity, a 10k

resistor should be placed in series with the multiplexed
inputs as shown in the application circuits.

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. This input is available on the
lCM7216A and 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 11. 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 11 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.

TABLE 1. MULTIPLEXED INPUT FUNCTIONS

FUNCTION

DIGIT

FUNCTION INPUT (Pin
3, lCM7216A and B
Only)

Frequency

Period

Frequency Ratio

Time Interval

Unit Counter

Oscillator Frequency

RANGE INPUT, Pin 14

0.01s/1 Cycle

0.1s/10 Cycles

1s/100 Cycles

10s/1K Cycles

CONTROL INPUT,
Pin 1

Display Off

D4 and

Hold

Display Test

1MHz Select

External Oscillator Enable

External Decimal Point
Enable

External DP INPUT (Pin
13, ICM7216D Only)

Decimal point is output for same digit
that is connected to this input.

INPUT A

4.5V

0.5V

50ns MIN

tr = tf = 10ns

COUNTED
TRANSITIONS

50ns MIN

FIGURE 9. WAVEFORM FOR GUARANTEED MINIMUM f

(MAX)

FUNCTION = FREQUENCY, FREQUENCY RATIO,
UNIT COUNTER

INPUT A OR

INPUT B

4.5V

0.5V

MEASURED

INTERVAL

250ns

MIN

tr = tf = 10s

250ns

MIN

FIGURE 10. WAVEFORM FOR GUARANTEED MINIMUM f

(MAX)

AND f

(MAX) FOR FUNCTION = PERIOD AND

TIME INTERVAL

ICM7216A, ICM7216B, ICM7216D

9-18

Frequency - In this mode input A is counted by the Main
Counter for a precise period of time. This time is determined
by the time base oscillator and the selected range. For the
10MHz (or 1MHz) time base, the resolutions are 100Hz,
10Hz, 1Hz and 0.1Hz. The decimal point on the display is
set for kHz reading.

Period - In this mode, the timebase oscillator is counted by
the Main Counter for the duration of 1, 10, 100 or 1000
(range selected) periods of the signal at input A. A 10MHz
timebase gives resolutions of 0.1

s to 0.0001

s for 1000

periods averaging. Note that the maximum input frequency
for period measurement is 2.5MHz.

Frequency Ratio - In this mode, the input A is counted by
the Main Counter for the duration of 1, 10, 100 or 1000
(range selected) periods of the signal at input B. The fre-
quency at input A should be higher than input B for meaning-
ful result. The result in this case is unitless and its resolution
can go up to 3 digits after decimal point.

Time Interval - In this mode, the timebase oscillator is
counted by the Main Counter for the duration of a 1-0 transi-
tion of input A until a 1-0 transition of input B. This means
input A starts the counting and input B stops it. If other ranges,
except 0.01s/1 cycle are selected the sequence of input A and
B transitions must happen 10, 100 or 1000 times until the

display becomes updated; note this when measuring long
time intervals to give enough time for measurement comple-
tion. The resolution in this mode is the same as for period
measurement. See the Time Interval Measurement section
also.

Unit Counter - In this mode, the Main Counter is always
enabled. The input A is counted by the Main Counter and
displayed continuously.

Oscillator Frequency - In this mode, the device makes a
frequency measurement on its timebase. This is a self test
mode for device functionality check. For 10MHz timebase
the display will show 10000.0, 10000.00, 10000.000 and
Overflow in different ranges.

Range Input

The RANGE INPUT selects whether the measurement
period is made for 1, 10, 100 or 1000 counts of the Refer-
ence Counter. As it is shown in Table 1, this gives different
counting windows for frequency measurement and various
cycles for other modes of measurement.

In all functional modes except Unit Counter, any change in
the RANGE INPUT will stop the present measurement
without updating the display and then initiate a new mea-
surement. This prevents an erroneous first reading after the
RANGE INPUT is changed.

Control Input

Unlike the other multiplexed inputs, to which only one of the
digit outputs can be connected at a time, this input can be
tied to different digit lines to select combination of controls.
In this case, isolation diodes must be used in digit lines to
avoid crosstalk between them (see Figure 17). The direction
of diodes depends on the device version, common anode or
common cathode. For maximum noise immunity at this input,
in addition to the 10K resistor which was mentioned before,
a 39pF to 100pF capacitor should also be placed between
this input and the V

or V

(See Figure 17).

Display Off - To disable the display drivers, it is necessary to
tie the D4 line to the CONTROL INPUT and have the HOLD

INTERNAL CONTROL

100Hz

INPUT A

INPUT B

INPUT

SELECTOR

INTERNAL OR

EXTERNAL

OSCILLATOR

INPUT A

ENABLE

CLOCK

MAIN COUNTER

RANGE SELECTOR

100

1000

INTERNAL CONTROL

CLOCK

INTERNAL CONTROL

INPUT

SELECTOR

REFERENCE COUNTER

FIGURE 11. SIMPLIFIED BLOCK DIAGRAM OF FUNCTIONS IMPLEMENTATION

TABLE 2. 7216A/B INPUT ROUTING

FUNCTION

MAIN

COUNTER

REFERENCE COUNTER

Frequency (f

)

Input A

100Hz (Oscillator

or 10

)

Period (t

)

Oscillator

Input A

Ratio (f

)

Input A

Input B

Time Interval
(A

Oscillator

Input A
Input B

Unit Counter
(Count A)

Input A

Not Applicable

Osc. Freq.
(f

OSC

)

Oscillator

100Hz (Oscillator

or 10

)

ICM7216A, ICM7216B, ICM7216D

9-19

input at V

. While in Display Off mode, the segments and

digit drivers are all off, leaving the display lines floating, so the
display can be shared with other devices. In this mode, the
oscillator continues to run with a typical supply current of
1.5mA with a 10MHz crystal, but no measurements are made
and multiplexed inputs are inactive. A new measurement
cycle will be initiated when the HOLD input is switched to
V

Display Test - Display will turn on with all the digits showing
8s and all decimal points on. The display will be blanked if
Display Off is selected at the same time.

1MHz Select - The 1MHz select mode allows use of a 1MHz
crystal with the same digit multiplex rate and time between
measurement as with a 10MHz crystal. This is done by
dividing the oscillator frequency by 10

rather than 10

. The

decimal point is also shifted one digit to the right in period
and time interval, since the least significant digit will be in

increment rather than 0.1

s increment.

External Oscillator Enable - In this mode, the signal at EXT
OSC INPUT is used as a timebase instead of the on-board
crystal oscillator (built around the OSC INPUT, OSC OUT-
PUT inputs). This input can be used for an external stable
temperature compensated crystal oscillator or for special
measurements with any external source. The on-board crys-
tal oscillator continues to work when the external oscillator is
selected. This is necessary to avoid hang-up problems, and
has no effect on the chip's functional operation. If the on-
board oscillator frequency is less than 1MHz or only the
external oscillator is used, THE OSC INPUT MUST BE
CONNECTED TO THE EXT OSC INPUT providing the time-
base has enough voltage swing for OSC INPUT (See Electri-
cal Specifications). If the external timebase is TTL level a
pullup resistor must be used for OSC INPUT. The other way
is to put a 22M

resistor between OSC INPUT and OSC

OUTPUT and capacitively couple the EXT OSC INPUT to
OSC INPUT. This will bias the OSC INPUT at its threshold
and the drive voltage will need to be only 2V

P-P

. The exter-

nal timebase frequency must be greater than 100kHz or the
chip will reset itself to enable the on-board oscillator.

External Decimal Point Enable - In this mode, the EX DP
INPUT is enabled (lCM7216D only). A decimal point will be
displayed for the digit that its output line is connected to this
input (EX DP INPUT). Digit 8 should not be used since it will
override the overflow output. Leading zero blanking is effec-
tive for the digits to the left of selected decimal point.

Hold Input

Except in the unit counter mode, when the HOLD input is
at V

, any measurement in progress (before STORE goes

low) is stopped, the main counter is reset and the chip is
held ready to initiate a new measurement as soon as HOLD
goes low. The latches which hold the main counter data are
not updated, so the last complete measurement is displayed.
In unit counter mode when HOLD input is at V

, the

counter is not stopped or reset, but the display is frozen at
that instantaneous value. When HOLD goes low the count
continues from the new value in the new counter.

RESET Input

The RESET input resets the main counter, stops any
measurement in progress, and enables the main counter
latches, resulting in an all zero output. A capacitor to ground
will prevent any hang-ups on power-up.

MEASUREMENT IN PROGRESS

This output is provided in lCM7216D. It stays low during
measurements and goes high for intervals between mea-
surements. It is provided for system interfacing and can drive
a low power Schottky TTL or one ECL load if the ECL device
is powered from the same supply as lCM7216D.

Decimal Point Position

Table 3 shows the decimal point position for different modes
of lCM7216 operation. Note that the digit 1 is the least signif-
icant digit. Table 3 is for 10MHz timebase frequency.

Overflow Indication

When overflow happens in any measurement it will be indicated
on the decimal point of the digit 8. A separate LED indicator can
be used. Figure 12 shows how to connect this indicator.

Overflow will be indicated on the decimal point output of
digit 8. A separate LED overflow indicator can be connected
as follows:

DEVICE

CATHODE

ANODE

ICM7216A

Decimal Point

ICM7216B/D

Decimal Point

FIGURE 12. SEGMENT IDENTIFICATION AND DISPLAY FONT

TABLE 3. DECIMAL POINT POSITIONS

RANGE

FREQUENCY

PERIOD

FREQUENCY

RATIO

TIME

INTERVAL

UNIT

COUNTER

OSCILLATOR

FREQUENCY

0.01s/1 Cycle

0.1s/10 Cycle

1s/100 Cycle

10s/1K Cycle

ICM7216A, ICM7216B, ICM7216D

9-20

Time Interval Measurement

When in the time interval mode and measuring a single
event, the lCM7216A and lCM7216B must first be "primed"
prior to measuring the event of interest. This is done by first
generating a negative going edge on Channel A followed by a
negative going edge on Channel B to start the "measurement
interval". The inputs are then primed ready for the measure-
ment. Positive going edges on A and B, before or after the
priming, will be needed to restore the original condition.

Priming can be easily accomplished using the circuit in
Figure 13.

Following the priming procedure (when in single event or 1
cycle range) the device is ready to measure one (only)
event.

When timing repetitive signals, it is not necessary to "prime"
the lCM7216A and lCM7216B as the first alternating signal
states automatically prime the device. See Figure 1.

During any time interval measurement cycle, the ICM7216A
and lCM7216B require 200ms following B going low to
update all internal logic. A new measurement cycle will not
take place until completion of this internal update time.

Oscillator Considerations

The oscillator is a high gain CMOS inverter. An external
resistor of 10M

to 22M

should be connected between the

OSCillator INPUT and OUTPUT to provide biasing. The
oscillator is designed to work with a parallel resonant 10MHz
quartz crystal with a static capacitance of 22pF and a series
resistance of less than 35

For a specific crystal and load capacitance, the required g

can be calculated as follows:

= Crystal Static Capacitance

= Crystal Series Resistance

= Input Capacitance

OUT

= Output Capacitance

= 2

The required g

should not exceed 50% of the g

specified

for the lCM7216 to insure reliable startup. The OSCillator
INPUT and OUTPUT pins each contribute about 5pF to C

and C

OUT

. For maximum stability of frequency, C

and

OUT

should be approximately twice the specified crystal

static capacitance.

In cases where non decade prescalers are used it may be
desirable to use a crystal which is neither 10MHz or 1MHz.
In that case both the multiplex rate and time between mea-
surements will be different. The multiplex rate is

for 10MHz mode and

for

the 1MHz mode. The time between measurements is

in the 10MHz mode and

in the 1MHz mode.

The crystal and oscillator components should be located as
close to the chip as practical to minimize pickup from other
signals. Coupling from the EXTERNAL OSClLLATOR INPUT
to the OSClLLATOR OUTPUT or INPUT can cause undesir-
able shifts in oscillator frequency.

Display Considerations

The display is multiplexed at a 500Hz rate with a digit time of
244

s. An interdigit blanking time of 6

s is used to prevent

display ghosting (faint display of data from previous digit
superimposed on the next digit). Leading zero blanking is
provided, which blanks the left hand zeroes after decimal
point or any non zero digits. Digits to the right of the decimal
point are always displayed. The leading zero blanking will be
disabled when the Main Counter overflows.

The lCM7216A is designed to drive common anode LED
displays at peak current of 25mA/segment, using displays
with V

= 1.8V at 25mA. The average DC current will be over

3mA under these conditions. The lCM7216B and lCM7216D
are designed to drive common cathode displays at peak cur-
rent of 15mA/segment using displays with V

= 1.8V at

15mA. Resistors can be added in series with the segment
drivers to limit the display current in very efficient displays, if
required. The Typical Performance Curves show the digit
and segment currents as a function of output voltage.

To get additional brightness out of the displays, V

may be

increased up to 6.0V. However, care should be taken to see
that maximum power and current ratings are not exceeded.

The segment and digit outputs in lCM7216s are not directly
compatible with either TTL or CMOS logic when driving
LEDs. Therefore, level shifting with discrete transistors may
be required to use these outputs as logic signals.

SIGNAL A

SIGNAL B

INPUT A

INPUT B

N.O.

100K

1N914

150K

0.1

10K

10nF

PRIME

FIGURE 13. PRIMING CIRCUIT, SIGNALS A AND B BOTH HIGH

OR LOW

DEVICE

TYPE

CD4049B Inverting Buffer

CD4070B Exclusive - OR

OUT

--------

where C

OUT

---------------------------------

MUX

OSC

-------------------

MUX

OSC

-------------------

OSC

-------------------

OSC

-------------------

ICM7216A, ICM7216B, ICM7216D

9-21

Accuracy

In a Universal Counter crystal drift and quantization effects
cause errors. In frequency, period and time interval
modes, a signal derived from the oscillator is used in either
the Reference Counter or Main Counter. Therefore, in
these modes an error in the oscillator frequency will cause
an identical error in the measurement. For instance, an
oscillator temperature coefficient of 20

PPM

C will cause a

measurement error of 20

PPM

In addition, there is a quantization error inherent in any digital
measurement of

1 count. Clearly this error is reduced by dis-

playing more digits. In the frequency mode the maximum
accuracy is obtained with high frequency inputs and in period
mode maximum accuracy is obtained with low frequency
inputs (as can be seen in Figure 14). In time interval mea-
surements there can be an error of 1 count per interval. As a
result there is the same inherent accuracy in all ranges as
shown in Figure 15. In frequency ratio measurement can be
more accurately obtained by averaging over more cycles of
INPUT B as shown in Figure 16.

FIGURE 14. MAXIMUM ACCURACY OF FREQUENCY AND

PERIOD MEASUREMENTS DUE TO LIMITATIONS
OF QUANTIZATION ERRORS

FIGURE 15. MAXIMUM ACCURACY OF TIME INTERVAL MEA-

SUREMENT DUE TO LIMITATIONS OF QUANTIZA-
TION ERRORS

FIGURE 16. MAXIMUM ACCURACY FOR FREQUENCY RATIO MEASUREMENT DUE TO LIMITATION OF QUANTIZATION ERRORS

FREQUENCY MEASURE

FREQUENCY (Hz)

MAXIMUM NUMBER OF

0.01s

SIGNIFICANT DIGITS

0.1s

10s

PERIOD MEASURE
f

OSC

= 10MHz

1 CYCLE

10 CYCLES

CYCLES

MAXIMUM TIME INTERVAL
FOR 10

INTERVALS

MAXIMUM TIME
INTERVAL FOR
10

INTERVALS

MAXIMUM TIME INTERVAL

FOR 10 INTERVALS

TIME INTERVAL (

MAXIMUM NUMBER OF

SIGNIFICANT DIGITS

1 CYCLE
10 CYCLES

CYCLES

RANGE

MAXIMUM NUMBER OF

SIGNIFICANT DIGITS

ICM7216A, ICM7216B, ICM7216D

9-22

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 lCM7216A or lCM7216B can be used as a minimum
component complete Universal Counter as shown in
Figure 18. 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
19 can be used. To obtain the correct measured value, it is
necessary to divide the oscillator frequency by 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 20 shows a frequency
counter with a

prescaler and an lCM7216A. Since there

is no external decimal point control with the lCM7216A and
lCM7216B, the decimal point may be controlled externally
with additional drivers as shown in Figure 20. 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 21 additional logic has been added to count the input
directly in period mode for maximum accuracy. In Figures 20
and 21, INPUT A comes from Q

of the prescaler rather

than Q

to obtain an input duty cycle of 40%.

FUNCTION

a
b
c
d
e
f

INPUT A

100pF

INPUT B

10K

TI.

U.C.

O.F.

RESET

LED

OVERFLOW

INDICATOR

.01/1

.1/10

1/100

10/1K

10k

ICM7216A

10k

22M

10MHz

CRYSTAL

39pF

TYP

DISPLAY

BLANK

DISPLAY

TEST

1MHz

EXT

TEST

OSC

39pF

EXT

OSC

INPUT

TYPICAL CRYSTAL SPECS:
F = 10MHz PARALLEL RESONANCE
C

= 22pF

= <35

FUNCTION

RANGE

HOLD

GENERATOR

FUNCTION

GENERATOR

1N914s

FIGURE 17. TEST CIRCUIT (ICM7216A SHOWN, OTHERS SIMILAR)

ICM7216A, ICM7216B, ICM7216D

9-23

FIGURE 18. 10MHz UNIVERSAL COUNTER

INPUT A

10k

F.R.

T.I.

U.C.

O.F.

LED

OVERFLOW

INDICATOR

ICM7216B

22M

10MHz

CRYSTAL

39pF

TYP

DISPLAY

BLANK

DISPLAY

TEST

EXT

OSC

EXT
OSC
INPUT

FUNCTION

HOLD

INPUT B

ENABLE

100k

CONTROL

SWITCHES

SEC

CYCLES

0.01

1.0

0.1

10.0

1.0

100.0

10.0

RANGE

10k

SEGMENT DRIVERS

RESET

DIGIT

DRIVERS

COMMON CATHODE LED DISPLAY

0.1

39pF

100pF

IN914s

ICM7216A, ICM7216B, ICM7216D

9-26

FIGURE 21. 100MHz FREQUENCY, 2MHz PERIOD COUNTER

a
b
c
d
e
f

100pF

10k

ICM7216A

100k

22M

10MHz

CRYSTAL

39pF

TYP

39pF

RANGE

HOLD

COMMON CATHODE LED DISPLAY

2N2222

CONT

RESET

0.1

10k

FUNCTION SWITCH

OPEN: FREQ.
CLOSED: PERIOD

INPUT A

11C90

CK1

CK2 QA OC

74LS00

10k

2N2222

10k

CD4016

LED

OVERFLOW

INDICATOR

ICM7216A, ICM7216B, ICM7216D

All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification.

Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate
and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which
may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.

For information regarding Intersil Corporation and its products, see web site http://www.intersil.com

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: ICM7216AlJl

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: ICM7216AlJl