ICM7216DIPI Intersil, ICM7216DIPI Datasheet - Page 9

• 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

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 0.1µs to 0.0001µs 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
frequency at input A should be higher than input B for
meaningful result. The result in this case is unitless and its
resolution can go up to three 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
transition 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
completion. 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
Reference 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
measurement. 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
9
ICM7216B, ICM7216D
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 14). 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 DD or V SS (See Figure 14).
Display Off - To disable the display drivers, it is necessary to
tie the D4 line to the CONTROL INPUT and have the HOLD
input at V
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
decimal point is also shifted one digit to the right in period
and time interval, since the least significant digit will be in µs
increment rather than 0.1µs 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
OUTPUT 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 crystal 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
timebase has enough voltage swing for OSC INPUT (See
Electrical Specifications). If the external timebase is TTL
level a pullup resistor must be used for OSC INPUT. The
other way is to put a 22MΩ 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 external 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
SS
.
DD
. While in Display Off mode, the segments and
4
rather than 10
5
. The